The three-day fast: Day Four

Last week, an article about the cell biology of fasting made headlines in the science news press.  Valter Longo cites evidence that a 3-day fast can rejuvenate our immune systems, with broad anti-aging benefits.  4 or 5 days may be better yet.


Socially, I was a late bloomer, clinging too tightly to love, driving away partners until I was in my 20’s.  I took a full year to allow Marsha into my heart.  Four years later, she broke up with me, and it launched a full-scale spiritual crisis, beginning with three days in which I had no interest in eating.

Those of you who have probed my Aging Advice page know that I fast a day a week, water only from Wednesday evening to Friday morning.  I have grown quite comfortable with this routine.  I ease off other disciplines on Thursdays, take a day off from aerobic exercise, allow myself to sleep more and be less productive.  I still do yoga, and like to take long walks on Thursdays.

But not since I was 28 have I fasted three days.  Monday morning, I awoke with the thought that this is as good a time as any to begin a three-day fast.  If I wait longer, I will have time for fear and worry.  My mind will play tricks on me, making it harder than it has to be.

I first became acquainted with Valter Longo’s work when, in 2004, he published a remarkable paper in Journal of Cell Biology based on work he did on yeast cells for his dissertation almost a decade earlier.  The results were considered so unlikely that it had taken him that long to convince a journal editor to take a chance and publish them.  What Longo had discovered was that when he starved a colony of yeast cells, about 95% of the cells would commit suicide, using the controlled death mechanism of apoptosis.  They would disassemble their proteins, dissolve the cell membranes, and turn themselves into food for the remaining 5%.

Impossible! replied the reviewers, schooled in traditional evolutionary theory.  How could such an adaptation evolve?  The colony must be closely related genetically, and how could the 5% be genetically different from the other 95%?  And whatever that difference was, the 5% would pass on their genes, the genes of the 95% would perish, and the next generation would no longer have the suicide adaptation.  We know this from basic theory, said the reviewers.  Longo must have made a mistake in his biochemistry.  These cells are not committing suicide – they are starving to death.

“Extraordinary claims require extraordinary evidence.*”  The paper was returned to him over and over, demanding more and more validation that what he saw was really apoptosis.  It took ten years before the paper was finally accepted for publication.

Today the fact that Longo discovered is widely accepted, though the message for evolutionary theory has yet to filter through.  But Valter saw the full implication of his work:  If yeast cells had failed to read the basic textbooks in population genetics, what other animals and plants might have been similarly negligent? Yeast cells are just one example of programmed death in the biosphere.  I was honored and excited the following year when Valter invited me to join him and Vladimir Skulachev in a paper for Nature Genetics on Programmed and Altruistic Aging.

In the intervening decade, Valter has been a ubiquitous presence in the biology of aging and of caloric restriction.  Of many creative innovations he has introduced, the one he is best know for is fasting as a cancer treatment.  He has documented that a three-day fast before chemotherapy has a powerful and extraordinary effect on the metabolism: The body’s normal cells are in a heightened state of protection, and are much more resistant to chemical toxins.  Hence the discomfort, headaches and nausea that generally accompany chemotherapy are attenuated – not to mention the long-term damage.  At the same time, the cancer cells are sensitized by the fast, so that more of them are knocked out by the chemo treatment.  This is a win-win for the patient, but Valter has undertaken a long and arduous campaign to convince oncologists that such a simple protocol could be so effective.  Worst of all, no one can make a dollar from fasting.

And what of the rest of us, who don’t have cancer?  This is the subject of Valter’s most recent work, that made science news headlines last week.  He puts together evidence from mice and humans that the three-day fast is a boon for us as well.  (Here is the full text, and here is an editorial in the same issue of Cell Stem Cell putting the article in context.)


Evidence in this week’s Longo Article

The experiment around which the paper is written involves depriving mice of food, then looking at the stem cell environment in their bone marrow.  Fasting actually increases the number of active stem cells in the bone marrow, even as the circulating white blood count is down sharply.  Two chemical signals are identified that mediate the process:  Both IGF-1 and PKA are down-regulated with fasting.

IGF-1 (insulin-like growth factor) is an old friend, first discovered in worms in the 1990s, and later identified as a pro-aging hormone generally.  PKA (protein kinase A) is less well known, and has many independent functions, de-activating several different signals by tacking on a phosphate group.  The cell’s energy cycle uses ATP, which yields energy and is recycled in its low-energy form, AMP.  Accumulation of AMP occurs when energy stores are low, and this signals a reduction in PKA.

The article makes a point that, though the benefits of long-term caloric restriction have been studied extensively, this kind of rejuvenation of the immune system has never been observed with CR alone.

Much of the article is theoretical, connecting decline of the immune system to many of the medical issues associated with aging.  Arthritis and even Alzheimer’s disease are rooted in auto-immune reactions.  The steep rise in cancer with age is believed to be related to the immune system’s failure to detect cancer in its early stages and to eliminate pre-cancerous cells.  It is to be hoped that rejuvenating the immune system might have broad anti-aging effects.


Why does it work?  
Evidence for programmed aging

In write-ups of this material, the failure of stem cells with age is described as “dysregulation”, and the reason the strategy works is attributed to a clearing out of damaged and ineffective immune cells from the blood, as they are converted by the body to food.  Perhaps you have noticed that this makes little sense.  Certainly Valter knows this better than anyone, given his history, but he has chosen not to fight the abstract battle about evolutionary theory, because he knows it would likely interfere with the credibility of his other, practical and life-saving work.

The point is that if the fasting body is able to rejuvenate and multiply the bone marrow cells that are responsible for blood and immunity (hematopoietic stem cells), then it is obvious that the body could do this as well or better when it has plenty to eat.  If it wanted to.  The fact that hardship and deprivation can induce the body to rejuvenate implies that aging is a programmed choice.  Even when it looks as though the cells are suffering damage over time, that damage is entirely avoidable (indeed, repairable), and it is only with chemical switches that the repair mechanisms are turned off as we age.  In PKA and IGF-1, Longo has identified two of the signals that keep the repair mechanisms dialed down, and make our health deteriorate with age.

Why is the body intent on killing itself?  It is an adaptation for population regulation, a response to natural cycles of boom and bust in population size.  When times are good, the population expands too fast.  Aging is a way of slowing down the population boom.  This is why we age more rapidly when there’s plenty to eat.  In times of famine, there is already plenty of death, and the danger is the opposite – that the population might plunge to extinction.  This is why aging backs off in the face of hunger.  (Ideas in this paragraph are not yet standard evolutionary theory, but this is a theme that I have developed in computer simulation, and it is the core of my contribution to publications in the field.)


Fasting in Ancient Religious Traditions

Though they are not controlled and not founded in a knowledge of biological mechanisms, traditional writings nevertheless embody experience of large numbers of people over a long period of time, and I look to them for ideas, for cautions and confirmations.  Before writing this piece, I had the impression that fasting was recommended in many religious traditions, and I eagerly googled associations with the 3000-year-old Ayurvedic (longevity) tradition of India.  I was surprised to learn that fasting for more than a day is regarded as an extreme practice, and that Ayurvedic texts don’t provide prescriptions or recommendations for long-term fasts, but rather cautions against fasting, suggesting that fasting practice has been prevalent for a long, long time, and the ancient Ayurveda was already reacting against it.

Frequent 12-24 hour fasts, however are recommended, even prescribed in the Ayurveda.  Eating the main meal early in the day is a practice that ancient traditions and modern medicine agree on.  Avoiding food for several hours before bedtime is part of yogic practice.  For Buddhist monks in the Theravada tradition, all eating is confined to the morning hours, implying a daily fast of 16 hours.


Implications for the clinician, for you and me

I find it remarkable, if no longer quite surprising, that in write-ups of the therapeutic effects of fasting, medical professionals and researchers focus on what we can learn that will help us produce a drug that mimics the benefits of fasting.  Fasting is providing all the benefits with little or no downside (except temporary hunger, need for warmer clothing); but medical science is busy search for drugs that will probably target just some of the signals that fasting sends, and will probably have more serious side-effects than fasting. Longo says that the constellation of benefits from fasting “would be difficult to achieve with any pharmacological or other dietary intervention.”

It is deep in the culture of today’s medicine that the patient is passive and it is the doctor who is the agent of healing.  Medical professionals de-emphasize all that the patient can do with diet, exercise and life-style modifications to improve his own health, despite the proven power of these regimes.  Part of the problem is in the conection to capitalism, which creates a focus on what can be healed profitably, ignoring remedies that cannot be sold.


Fasting and weight loss

It is my experience that I don’t lose weight from fasting, presumably because I eat more before and after a fast.  Other people I know have reported similar experiences, and both ancient texts and modern medical advice agree that fasting is not an effective way to lose weight for most people.  That doesn’t mean it won’t work for you, if you have experience to the contrary.

Steve Hendricks published in Harpers an account of his own 20-day fast, embedded in a very readable account of some fasting history.  Summary here for those without a Harpers subscription.


Personal experience

I’m now in Day 3, and it seems long only psychologically.  In my weekly Thursday fasts, I sometimes experience headaches (one week in 5 or 6), and that hasn’t happened.  I have the luxury of no busy schedule, no deadlines.  That’s a good thing, because productivity on fast days is not reliable.  During fasts, I don’t have the focus to be able to write computer code, and writing is often slow.  But often deep and creative thoughts are given to me during fasts.

I can sit contentedly for long periods of time without feeling a need to accomplish anything, or even to get up.  I tend to a shorter night’s sleep, but enjoy naps during the day.  Once in my life I tried public speaking on a day I was fasting, and I won’t do that again.  Words come out more slowly, trying the patience of the audience.  (My one experience was speaking to the Caloric Restriction Society, and my audience understood and were patient.)


How long is optimal?

I wrote to Valter yesterday, asking this question.  Does he have evidence from people suggesting how long it takes for the immune reset?  Is it different for people who start with a lot of fat on their bodies compared to people who have nothing in reserve?  His answer was short and to the point:

3 days is optimal for mice. For humans 4-5 minimum, depending on what you are trying to achieve

You can already tell I have a lot of faith in Valter as a scientist, and it is easy for me to believe that, from his experience, he knows more than he is able to publish.  So I’m deep into Day 4 as I finish writing this.  I’m a little spacey and my rhythms are disrupted, but I’m not suffering or food-obsessed.  I plan to start fruit or juice soon.

172 thoughts on “The three-day fast: Day Four

  1. dont believe the studies you are reading unless significance is very high, and that too every graduate student will tell you is a mesurment error =, hey if you dont publish you dont have a job…

  2. Josh,
    the most important part of the blog’s entry is “3 days is optimal for mice. For humans 4-5 minimum, depending on what you are trying to achieve”.

    Could you contact Longo again to have a clue of the period of fasting needed for humans?. Once per month/3 months/6 months…?.

    Thanks. Santiago

      • I do take supplements, but I don’t know that there’s any theory on the subject, and certainly no data. There are some supplements I think are better absorbed on an empty stomach.

        • I just completed a 3.5 day fast, and if I had only read this article sooner I would have made it a five day fast. There is a 1935 book I read, during this period, by Herbert Shelton (The Science and Fine Arts of Fasting) who supervised 35,000 fasts over a 40 year career.

          According to him, it was common to see cancerous tumours dissolving from fasts of 3 days to 3 weeks. The extensive documentation and careful recording of observations, down to the specific gravity of urine, the % of each and every major organ system affected, is mind blowing. To say there is no literature on fasting is to say, there is no modern literature on fasting. But I think it is safe to say his book will be in demand once this forgotten art is given (sigh) scientific credence. And no, we do not need an expensive drug that will do this for us! Fasting is free – in fact it has saved me about £60 on food already!

          Shelton calls a “fast” a period when only water is taken. If you’re taking lemon water, or a little fruit, or a little salad, or a grapefruit here and there, it’s a diet, not a fast.

          And as for chemical vitamins, the entire point is to hand the body some down time in which it can recycle and digest diseased or tumour tissue. I have cancer and could feel a scratching, gnawing feeling in the tumour areas which impressed me as significant.

          I had read that 3-4 days was enough, from all the media articles. Damn, damn, damn. Now I need to start again.

    • My chi gong teacher, or, my teacher who follows taoist practice of his family, fasts for three days four times a year, once in each season. He emphasizes that the liver is cleansed. but also the kidneys. the glicogen stores in the liver beocme depleated after 48 hours in women an 72 hours in men, on average. The goal of a three day fast is to use up all the glycogen stores in the liver and enter a state of ketosis.

      • How does the chi gong teacher know? What biochemical analyses did he make? Confident men make definitive statements out of thin air. And followers believe them!

        The above blog should start by saying that the 3-day fasting is for mice only. Or an update could be posted.

        • hym, I’m not sure if the article has been revised since you typed your comment, but it does make it very clear that a three day fast for mice is not the equivalent of a three day fast for humans.

          Re: comparing rodents with mice, the problem is that research on humans if not nearly as advanced as that which has been done on mice. You can fast a mouse (periodically) for half of its typical lifespan, but can’t do the same in a controlled way for humans. So we extrapolate from the evidence really are just guessing, sometimes.

          Valter does make it clear that the length of time that a human would need to fast, to achieve the same results, has not really been determined. Valter Longo’s guess is 4 to 5 days; but he makes it clear in other interviews that it’s only an educated guess.

  3. Thanks Josh, great article as usual.

    Just curious if you had thoughts on consuming your regular supplements during your fast, as my understanding is that creating a nutrient poor environment is probably favourable for its duration.

    If taking a multi etc is advised against for this period, would you also advise against taking a supplement such as HMB (beta-hydroxy-beta-metahybutyrate) free-acid, in order to minimize lean tissue from being catabolized?


        • I’ve also read that antioxidants–vitamin d and vitamin c and oregano oil and other supplements high in antioxidant activity–will abolish autophagy. Do you know if there are any supplements that can be taken that will enhance fasting and not abolish autophagy?

          • Hi,
            I thought I would throw in my 2 cents worth, considering I have done years and years of reading on fasting.
            It is generally considered counterproductive to take supplements during a water fast as it stops a lot of the healing processes. The body needs to detect that there is no minerals, vitamins or amino acids coming in through the digestive system before it will switch on some healing activities. For example, your body will not clear out excess calcium deposits (which everyone will have to some degree).
            Your body will also go into an effective mode of recycling and saving current minerals and vitamins in the body- so as long as you weren’t malnourished beforehand you have nothing to worry about.
            Also, there is very little muscle loss on a long term fast, as by day 2 for women and day 3 for men, the body goes into muscle conservation anticipating that there is a food shortage and it will need to walk for many miles soon to gather food. There is a good clip on youtube from Dr Jason Fung explaining this.
            Hope this helps!!

      • I always wonder why the ‘fasting mimicking diet’ (FMD) of Valter Longo works. I have read many articles suggesting that even a supplement pill or capsule may stop autophagy, so, how is it possible that eating the FMD apparently does not stop it?
        Do you have an explanation for this?

  4. How many times per year is this appropriate? Does he offer any opinion on the effects of short time restricted water use for humans?

    • How often? I don’t think there’s enough data yet to say what is optimal. It’s also almost certainly true that there is large individual variation in our metabolisms and even more in what we are able to tolerate. Valter has talked about a 4-5 day fast once a month as therapy for auto-immune disorders. My guess is that most of us would have to be highly motivated by health conditions that are interfering with our lives before we would take that on.

      I’m leary of water restriction, and afraid we could hurt ourselves. You might write to Jeff Bowles , who has done small-scale and informal experiments with water restriction.

          • Could you please post the link to this video. I’m very interested to see the relationship between fasting and autoimmune diseases

      • ” Valter has talked about a 4-5 day fast once a month as therapy for auto-immune disorders. My guess is that most of us would have to be highly motivated by health conditions that are interfering with our lives before we would take that on.”

        This is very interesting to me, hearing his take on fasting and autoimmune disease. I have an autoimmune disease, psoriatic arthritis, and through other channels came to periodic fasting. I would say from personal experience, fasting 4-5 days 1x a month makes it difficult to maintain muscle mass, but has the benefit of lowering the metabolism, making it easy to exist on less food.

        I have found fasting from 3-10 days (depending on how the fast is going and how busy my schedule is), 4 times a year to be incredibly beneficial to my autoimmune disease. I achieved improvements immediately, and remission without medication within 2 years.

        • I have found that fasting DOES diminish episodes of violent rash/ich on my skin. When it becomes too tough for a 4 day fast, I start/end w/ 1 day to follow up w/ 3 day of vegetable juice regime.

          • Sophie, that is a good way to cope with fasting challenges. thank you for sharing it.

        • Could you tell me more about how you fasted for psoriasis? Is it a complete water-fast, or do you eat some food? Any details you could post would be incredibly helpful, since I’m having serious problems with it.

          • Z, I did a complete water fast, preceded by eating very nutritious foods for a few months, and follwed by the same. I learned about it not from Valter Longo’s work but from a book called “Fasting and Eating for Health” by Dr Joel Fuhrman. There is a chapter on autoimmune diseases that is very specific and informative. I fasted for shorter duration than the 14-day fasts mentioned in the book because I am in contact with the author and he recommended that shorter (2-4 day), more frequent (bi-monthly) water fasts are safer and more effective with autoimmune disease. Best of Luck!

          • I do lots of fasting but my daughter who has had horrible psoriasis for 20 years won’t fast. I inadvertently found a cure for her psoriasis. I mixed a quarter cup of Banyan Botanicals cold-pressed sesame oil (has to be cold-pressed and other brands didn’t work)…mixed with 1 dropperful of Source Naturals Wellness Oil of Oregano…mixed with a tablespoon full of Amazing Herbs Black Cumin Seed Oil. All are available on amazon and much cheaper than all the psoriasis meds she’s bought over the years. I made up the concoction with that recipe and she put in on one elbow (leaving all the other psoriasis untreated) and her elbow was clear of psoriasis in a few days. She then slathered it all over her body and all her psoriasis went away. We tried replacing different oils when we’d run out of one, but only that exact combination worked. Let me know if it works for you. [email protected]

        • I used to have pollen allergies in the spring (trees) and late summer (grasses) and that went away completely after a series of 4-5 day fasts I did this past winter.

          • I have seasonal pollen allergy in the spring (trees – birch in particular). I was suffering terribly and the only thing that helped was Flixonase which has steroids in it.
            I have been on an intermittent fasting protocol for 2 years. My symptoms went down significantly – I get by without ANY antihistamines or nasal sprays. The symptoms became so mild that I dont take anything anymore.
            Currently I am trying a 7 day fast. My season will start in a couple of weeks so I am curious what this year will be like.

          • Kamil-
            That’s great news – I wonder how many people who suffer from allergies could benefit from fasting.
            Do you know about spirulina for allergies? This, too, works for some people.
            – Josh

        • Simone O’Shea,

          Could you send me an email at [email protected] ? I was diagnosed with psoriatic arthritis, and I’m gathering data on what has worked for people to put it into remission.

          I noticed some improvement on a recent 3-day water fast (but not enough improvement). I will start a 5-day fast this weekend. I also bought the Joel Fuhrman book that you mentioned.

          If anyone is experimenting with fasting for psoriasis, please send me an email so that we can figure out what works.

          • Don’t guess. Find, download, read, and learn how to understand the published peer reviewed papers. In addition, you can find a lot of studies on fasting, often termed “Short Term Starvation”.

            Also note the ongoing human clinical trials. The truth behind Guess work is teased out with hard science.

          • Yes, that is what I’m doing. 🙂

            There are too many anecdotes in blog posts and forum comments. I am not aware of any studies that provide a definitive answer, and our time is limited. Nobody knows why, for example, a 5:2 diet works for one person but not another. (I have suspicions about that, but no evidence yet.) Through interviews, data collection, and machine learning, we will try to identify common factors between the success stories, and then professional researchers can perform their peer-reviewed studies based on our independent investigations.

            If anyone with psoriasis or similar autoimmune disease is interested in participating in this project (whether you are using fasting or not), please send me an email: [email protected]


          • I don’t think we have “too many anecdotes”. The truth is that we don’t have large-scale placebo-controlled double-blind studies for any of this. We’re still at the stage of collecting people’s personal stories and trying to form a hypothesis. The controlled studies will come in due time.

            In the meantime, I suggest self-experimentation, guided by stories of others’ experience. How often we just look at averages reported by large-scale studies, and forget that every treatment works for some people and not for others. We can take chances guided by the odds, but in the end, we’re left with a one-person trial to see if I’m one of the people for whom this works.

          • By “too many anecdotes”, I mean that there is not enough data to understand how to stop this disease. The only thing that someone like me can do is to read studies and brief anecdotes in blog comments and forum posts. These anecdotes do not contain enough information to act on, such as: why did a certain factor work for one person but not for another? I suspect that there is more than one factor in all of these cases, but no one knows the answer. Most doctors have no clue – diet and exercise were not mentioned to me when I got the diagnosis until I asked about them specifically. It turned out that a three-day fast did more for my condition than 5 to 6 weeks of three different topical medications. (Thanks for your blog post.)

            When one has an autoimmune disease that is incurable, that can lead to severe disability and even mutilation, where the medicines are sometimes as bad or worse than the disease’s symptoms, there is no time to sit around and wait for “they” to do something, or to make wild guesses based on extremely sparse information.

            I’m not even sure if anyone has collected comprehensive personal stories with the information that I’m looking for, so that’s what I’m doing. Not only that, but I will log data from as many people as are willing to participate. I don’t expect to find a definitive answer – only to find new clues that someone else may be able to use for their studies. I am in a good position to do this task at the moment.

            I’m going to continue the self-experimentation with a five-day water fast starting tomorrow. (I will post regular updates in my blog.) The previous three-day fast did help by the third day, but that was not enough by itself.

          • I’m newly diagnosed as well. I am trying to do AIP. It has been exceedingly hard for me to give up sugar. Pretty sure it’s at true addiction. So, even the slightest bit is causing me to crave more. So, I started looking into fasting to jumpstart my body and give up sugar cold turkey. I haven’t had any gluten, grains, dairy, spices, artificial sweeteners, processed foods, nightshades, eggs or nuts in two weeks except that I’ve had ice cream twice. Ughh. So mad at myself. So, if you find any good info you want to share, I’d be greatful. I think I’ll have to start w 3 day green juice fast. I’m not sure I can do just water yet. My blood sugar tends to drop quickly

          • Jen –
            Please be gentle with yourself. It’s counterproductive to steel yourself and perform with willpower something that you can’t sustain, and may make you react later on with a binge. Any change worth making is worth making gradually.
            Of course, you know your body and your temperament, and I don’t. So certainly apply your body wisdom first, and my advice second.

      • I just completed my second 4 day fast (yesterday) in 4 weeks and feel great. On each day I felt a burning in my lymph tumour, and on the second day, at night, i felt like someone was stabbing it. In the morning the formerly hard edge at one end was now more like gravel to the touch. Quite frightening, in a way, while it was happening, as I couldn’t stop it or control it.

        And I had an amazing dream on the 3rd day: I was holding a leaf the top of which was glowing as if burning,like an ember, until about 15% had burnt and fallen away.

        And then the thing erupted into the most amazing flowers – curling stems, purple and violet and white leaves blossoming out – incredible and bursting with life. Quite hard to describe as I’ve never seen such flowers and plants before.

        In my dream I tried to get my iphone to film it, as I knew nobody would believe me – but the thing was stuck and wouldn’t work. very frustrating. but the message was clear as a bell to me. I will try 4 days a month for sure.

    • Re: the questions which keep coming up, “How long should the fast be? And how often should you fast?” Longo recommends doing a multiple-day fast at least four times a year.

  5. “Part of the problem is in the connection to capitalism, which creates a focus on what can be healed profitably, ignoring remedies that cannot be sold.” Baloney. Idea flourish if they work. If they work, they develop a following. No commercial interests have pushed fasting, yet for a hundred years (think Paul Bragg or Benarr MacFadden), it has had a steady and popular constituency. Same with vegetarian eating. Or Paleo dieting. Or the running craze that started back in the 70’s. Or Crossfit. Or. . . many other worthwhile ideas. Bottom line – if it works, has some merit, there will be a following and the idea will enjoy success.

    • David –
      There’s some truth in what you say. Good ideas can catch on eventually whether or not they are pushed commercially. But those that have commercial backing have an enormous advantage, and some really bad ideas find success because they have commercial backing. Witness: HRT, statins, proton pump remedies for acid reflux, chemotherapy.

      And there are many potentially good ideas that remain on the fringe because we don’t know how well they work. We don’t know how well they work because they haven’t been tested in large-scale, placebo-controlled double-blind trials. And the reason they haven’t been tested is that no one has invested the money to test them, and the reason no one has invested the money is that if they succeed, they are not patentable, so there is no way to make a profit.

      This is why it is so important to have independent funding for clinical trials. There is no substitute for government-funded research that has no pecuniary interest in the outcome.

      I have maintained that the most promising 4 anti-aging drugs presently available are aspirin, metformin, deprenyl, and melatonin. None of them is patentable, so the information that we have on their effectiveness is limited.

    • One of the problems is ignorance. If the AMA and the ACA and the medical journals refuse to publish anything to do with nutrition and fasting as “quackery”, and the media treat it as nonsense, nobody will even know about it.

      My own father was a surgeon in the 1950’s, and became a hematologist for the rest of his entire career. His published paper on drug aquired immune deficiency is still quoted in research papers. Now, when he was diagnosed with cancer late in 2006, he was told he probably had two years to live. He got used to the idea, and resolved to see his grandkids, travel, play a bit of tennis, and make the most of it.

      In 2007 a colleague told him about this new “silver bullet” chemo which could possibly give him an additional two years. I even remember him telling me all about it. He thought at 74, that wouldn’t be such a bad span of time, so he signed up. Now, having being surrounded by orthodox corporate medicine for 50 years he’d never given a thought to the alternatives.

      They started him on the exciting new silver bullet life extending chemo late in February 2007, and he fell apart. In March he was in the A&E of Toronto Hospital having his lungs drained. In the savage Canadian Winter, in a wheelchair, being pushed across University Avenue to line up with dozens of Chinese immigrants. All true.

      After the March chemo he couldn’t even get out of bed. He told me, “I’m afraid the wheels are coming off..” and now tumours started to emerge under his eyes. In April his last chemo practically killed him. In May he was moved into a hospice and a week or two later he passed away.

  6. Well I’m into day three now. First time I try this. On a water+salt faste. I’m surprised by how little hunger I’m feeling.

      • Well I cut it short after 72 hours. But that was not due to extreme anguish or anything of the kind, I had not really planned doing this at all. The next time I do it I will aim for four days.
        I want to emphasize how easy this was, I’m male and 30 years old and usually eat a lot due, I excersize a lot (4-5 days/week).
        Despite this, the faste was easy, in fact it was weirdly pleasant in a way that makes me look forward to doing it again. This is an important distinction for me since it will make it a lot easier to repeat.
        I was able to work without any problems and ride my bike 25 kilometers (at a leisurely pace) during these three days, and most importantly I slept well.
        I only ever felt a bit of a headache when I resumed eating but that was no big deal either.

      • Hi, just wanted to know doing the course of fasting am i to eat fruits and vegetables while drinking plenty of water or am i to drink water only without eating anything?

  7. Very glad to find your blog, Josh.

    My name is John, and I am 60, and felt old age beginning to swallow me up about 18 months ago…and started fasting two days a week…on Sundays and Thursdays…I was 215 pounds and 5″ 10″…..and started doing some simple exercises 4-5 times a week…stretching, pushups and abdominal exercises, and walking about 3 miles or so most days…and I have dropped to about 175 pounds so far…and am more flexible and feel better than I have since I was a very young man. The general feeling of inflammation and stiffness that had gradually swallowed me up…it is gone.

    I am now at the point that I have a a very settled routine, that works great for me, so far. I find this routine quite refreshing and WAY EASIER than eating daily…

    I don’t eat anything, but just drink eight litres or so of water daily, along with unsweeted herbal teas…mate’, chamomile and peppermint mostly….for the first 48 hours of my week starting Saturday evening after dinner…

    Then I eat normally, for 48 hours starting with dinner on Monday evening, through dinner on Wednesday evening. I still drink my 8 litres or so of water daily during this 48 hour period….

    Starting after dinner on Wednesday evening, I once again don’t eat anything for 48 hours…till dinner Friday evening…but drink 8 litres of water a day plus the teas…

    Then starting with dinner Friday evening…I eat normally for the next 24 hours through dinner Saturday evening.

    I feel absolutely great….and improving constantly. Pretty amazing.

    And I don’t think it is just the breaks from eating…though for sure they are a big part of it. It is also huge, in my opinion, to drink a lot of water…pure water. And the exercise…stretching, resistance, and walking…that’s been huge also. It has been “eat less often, drink more good water more often, exercise more often”…these three things really complement one another.

    I think most people are in a state of semi-dehydration, most all the time.

    One obvious question is…”wow, you must spend all your time urinating!”…You would think so…but not at all. As I have eaten less, and gradually developed the appetite for a LOT of good water in my system…my bladder capacity has increased hugely…and now, when I do get to the point where I have to urinate….it is a LOT, for sure…but I don’t have to run to the bathroom every 20 minutes or anything.

    I personally find NOT EATING way easier than eating.

    I find I am getting way healthier and more youthful looking and feeling….even liver spots I have had for many years are flat-out disappearing off my skin. No joke. I didn’t even know this was possible, but it is. So what else is going on inside me? Pretty encouraging stuff. Except for my white hair, when I stand in front of a mirror these days, I look better than I did when I was 20….(I was a total druggie wastrel from 13 to 20 years old, so this is not as amazing as it might seem….LOL)

    So Longo’s findings are huge…even more amazing. You can take your body to a place where the whole blood producing systems reset, with brand new stem cells being produced?!!! Incredible!

    It is bizzare, though, how the world media sound-bites this stuff….they turned it into “fast for 2 days and your whole immune system will reboot!”

    PLEASE DO find out a little more from Dr. Longo if you can, Josh…please.

    If someone wants to get their blood systems/immune systems regenerated…about how many fasts a year, and how long for each fast? Or is that information already there…in his “4-5 days, once a month” for auto-immune disorders…suggestion that you mention above? Can you tell me where to find the article where he suggests this?

    For me, it would be simple to do that…all it would cost me, is to once a month, just eliminate my usual eating from dinner Wednesday to dinner Friday…and I would be fasting that week from Saturday night to the follow Friday night….6 days. You say above that “My guess is that most of us would have to be highly motivated by health conditions that are interfering with our lives before we would take that on.”

    I would think the mere gradual approach of old age to be followed at some point by death….should be enough for a prudent person to motivate them….if they knew there was actually something they could realistically DO that would actually make a huge difference. And clearly, there IS!!

    I think your appraisal of human nature is accurate though, Josh…most of us…most all human beings are NOT prudent, and find themselves frantically trying to shut the barn door, after the cows are already out. But for me at this point, just the desire to live as long and full life as I possibly can, for the sake of love and to help others….this is enough motivation for me. If you can deny yourself short term and by doing so, live who knows how many more useful years of love and service than you could otherwise…and you don’t do it…how selfish is that? And how much regret would you have?

    Especially since not eating is (for me at least) so easy and enjoyable, for the most part. At times, of course, it is socially a bit awkward…and at times physically it is difficult…I experience at times, when junk in my system is being cleaned up…times of feeling lousy, times of low energy…but SO WHAT?….I felt much lousier, and in general had much less energy, when I was eating every day. Eating all the time is what is truly exhausting…NOT taking a break from eating.

    Anyway, thanks for your blog. I totally agree with your statement that, ” The best thing we have going for us is our shared experiences.”


    • This is a great story. I don’t know anyone else who has managed to build a life around two 48-hour fasts every week. When I fast, I give myself a day off from aerobic exercise and also from demanding brainwork. I can’t do public speaking, and writing is often difficult. It frequently feels like I can think but I can’t gel the thoughts or verbalize them.

      Dr Longo’s comments that I quoted were in an email to me, and not a published article. I assume that, like most researchers, he has some ideas he’s pretty sure of but not yet ready to substantiate them in a journal article.

      • Josh, this is John David. I wrote the above to you a few months ago…and since then have continued in what I was doing…two 48 hour fasts each week….but for the last four months, at the end of each month, I also fast for five days.

        It is easy for me…I gain back whatever weight that I lose quickly and enjoy doing so…because I really like eating, especially after I have denied myself eating for a while…food tastes SO GOOD…so much better than it does when you eat constantly.

        I would like to write to Dr. Longo and ask him…not for a “prescription”…….but for his “best guess” opinion, from what he has seen in his research so far…as to whether a complete five-day fast each month is enough to most likely trigger the renewal of the immune system….no guarantees, of course…just his best guess.

        I just think it would be a shame to spend years fasting five days straight each month…and not accomplish what you could have accomplished…if you had just fasted, say, six days straight each month instead…or seven, or whatever. Once you haven’t eaten anything for five days…it is no big deal to go another day or two…on most levels. Socially, it can get pretty challenging though…but I really want to know what his idea would be about this…how many days of fasting might constitute the best monthly fasting cycle that would give the best shot at maximum benefit.

        Thanks much for your blog and your help!


        John David

        • I think 5 days of water fasting once a month will have have a regenerative effect on the immune system. I’m doing that too: 3×36 hours each week and 5 days once a month. I take a B complex vitamin and Vitamin C while doing the prolonged fast. Floss and brush and swish with a strong saline solution. I still go to work and it’s fine. I don’t have any cold or flu symptoms this winter at all.

    • Nice story

      Some comments
      1) 8 liters of water per day? That seems like a lot
      2) I heard of water fasting or combined food and water fasting
      3) what kind of fast did Jesus do for 40 days? I dont believe there were any details about it. Food fast at minimum, but I suspect food and water fast for 40 days straight.

      Ive been reading more over last couple years about caloric restrictions being helpful. But I could have swore of heard something similar with water fasting or restrictions. I suspect not many would try water fasting because of it potential dangers?

      About Jesus, I don’t believe he was using up lots of energy during his fast. He said it was suppose to be in private and that we should pray. For 40-days, some of the prayers may be to let me be alive at the end of it. jk I bet he was praying and mediating almost all of that 40-days ie making the fast not only a physical cleansing, but spiritual and mental cleansing.

      anyone have comments, thoughts about this?

    • Wow. What a great write up.
      I’m just looking into this fasting idea and your blog made me want to adapt your diary into mine. Here’s some history of me, male 45, fairly fit, I run 4 miles a few times a week and run at least 2 half marathon a year, I eat well, not too much processed food, but I do over eat! Also in the past I have had a problem with wine, totally stopped drinking wine now for a while, but need to cut down on the beer! Anyway my weight is always 79kgs or very near! Even if I diet for a while it always comes back to that weight! I’m finding more and more I have less energy and life is a tough slog, so I’m going to start a 1 day fast twice a week, Mondays and Thursdays. I will keep a diary and a photo journal of my skin, weight hair etc. I also will be refraining from any alcohol and cutting out caffeine.
      Wish me luck. I will report back in 2 weeks.
      P’s any tips or advice appreciated.


      • John –
        Each one of us is in a one-person experiment. You’ll find out what works for you. A lot of people couldn’t just start up deciding not to eat 2 days a week. Do let me know how the first 2 weeks goes.
        – Josh

  8. I have been doing caloric restriction for about 25 years, all stable and working. I am trying the five day fast now due to this research. Did Valter Longo tell you how many waves of this is needed? How much reset gets accomplished with one fast? When doing waves of fasting, what is the spacing that he suggests? I was thinking about doing this once a year, but if the waves are needed in order to get the proper effect, knowing how many waves is important. Also, is there any research saying how long the effect lasts? Is the immune system back to where it started before the fasts after, say, a year, or does it last longer? I know the research is still very new and answers to these questions may not exists. But any suggestions would help, especially on the need for waves of fasting, and the spacing. It might be better not to do waves of fasting if one fast takes care of the reset and it lasts awhile for a person following caloric restriction. So knowing how much one fast accomplishes is really helpful.

    • Dear Courtney –
      Valter mentioned monthly fasts for 5 days in an email. But I am pretty sure there is only anecdotal evidence at this point, and we are only guessing about what works. You can email your detailed questions to Valter, as he is very good at responding to queries, but I suspect you’ll hear the same thing – we just don’t know yet.
      Listen to your body. See what you can tolerate. Monitor progress in how you feel. Share your experience with others in our community. It’s not perfect, but until we have a lot more data, it’s probably the best we can do.
      – Josh

      • Hi Josh:
        First – I really appreciate your website.
        By way of keeping up the conversation about fasting which seems to me, other than the supplements you recommend and exercise, a possible additional longevity aid until something else such as scientific progress along the lines of doing something about the epigenetic programming you have been talking about is achieved:
        I have tried the four day fast four times now. The two benefits that may have resulted are: 1). A 15 lb weight loss (I lose about 8 lbs and about 4 lbs stick, along with a gradual weight loss that I have been trying to achieve for a total actual loss of 25 lbs) and 2). An apparent drop in my blood sugar reading from 99 (near pre-diabetic) to 79 (first time in 20 years I have been that low for the standard blood test that my primary care physician gives me one a year) (happened about a month ago).

        Of course I have not been sick the last five months and I perceive that I feel well.
        The fasts have been over a 5 month time. My reaction to the fasting is that the first two days are easy and the next two days are less so. These are water plus nutritional supplement fasts.
        From the posts I perceive that I may be overdoing the frequency of the fasting?
        Incidentally SmartHealth has published an article on Nov 14 about Longo’s work which may suggest 3 days of fasting is okay. At least that is the way I read it. It also discusses recent clinical trials.
        Ed Quinn

        • I have no reason to think you’re “overdoing the frequency of fasting”. This is not something that has been studied in detail, and it probably cannot be done in any controlled and systematic way because randomized trials are impossible. Intuition tells me that individual variation is most important, and that you have found a schedule that works for you.

        • Well Valter recommends a 4-5 day fast monthly actually and a mostly plant based diet. If you watch the BBC documentary “Eat Fast and Live longer”, that is what he says.

  9. I have been doing intermittent fasting since 2008, 3 times a week, for about 32 hours. I eat a late snack finishing off an eating day, then don’t have any calories the next day and only eat a breakfast the following day.

    I just came across this research on stem cells and am trying a four day fast. I’m at 48 hours now. It’s a long weekend around here as Monday is a Civic Holiday.

    I think I would need a long weekend to do this, as it would interfere with work. Though I can do alternate day fasting and work fine. Fortunately there is one long weekend per month in the summer here.

    • Thanks for telling your story. Different bodies can accommodate to different regimens, but it is only by trying and gradually accommodating ourselves that we learn what we can tolerate.

      I’m interested in whether these long fasts interfere with your ability to think, to listen, to socialize, to enjoy life, or do you find some of your life activities are enhanced by fasting?

      • If anything I notice enhanced mental clarity on fast days, though maybe a bit less energy. I also bike to work in the summers about 25km or 15 miles, then back home at the end of the day. When I first started doing this type of fasting I used both ketostix and a home glucose monitor and my blood sugar went up after the ride. I also feel great on the ride, when I am exercising I get an energy boost.

        I do drink zero calorie drinks on fast days – black coffee (varies how much over the years, now only occasionally), green tea or black tea, diet soda, and water of course. When I’m at home on the fast day it’s generally just water. At work it tends to be something caffeinated.

        Supplements . . . only melatonin (before bed) and just recently (last 3 weeks) timed released niacinamide.

  10. Socially, everyone at work, at most places I’ve worked, think it’s strange to have fast days. I do enjoy going out for lunch with friends, usually Tuesdays or Thursdays, sometimes Fridays. I don’t think fasting affects my ability to listen or think. I write code fine on fast days, I don’t notice I’m fasting when I’m coding. It may make me more irritable – or did when I first started fasting. I guess I’m used to it now.

  11. I did a 24 hour fast yesterday. I eat low carb, so I suspected that’s why I didn’t feel shaky or break out in a cold sweat like what happened back in the 80’s with my first fast. That’s why it took so long for me to be able to try it again. I am involved in a lower carb eating style community. I have experienced long periods between meals, bicycling for hours without eating and not bonking has helped me have the guts to sit in cold tubs and to try fasting again. I monitored my blood sugar to see what happens and found that if it goes into the 60’s I am spaced out and tired which happened yesterday afternoon around 3 (hour number 19). I did a 24 on and 24 off. So when I ate last night I checked post prandial food ingestion several times. It remained in the low 90’s then up to 111, 3 hours after eating. This morning I checked and my blood sugar was in the 70’s which is has been my goal. I am not diabetic. But we do have it in the family. I already have some beta cell dysfunction in my pancreas from the high carb diet I have been on since the 70’s. I am 62 years old and changed my diet just a few years ago when I turned 58 (2011). My CRP levels have trended up since I started taking the test in 2004. That was my motivation to start fasting. I follow docs that are into paleo eating and looked up CRP on their blogs. You might enjoy reading this about fasting, IL-6 and CRP levels (but you probably already know about it):

    • I cut mine short at 165 hours. I felt a bit tired at that point, but I didn’t feel tired or hungry after day 3.

      After I broke the fast I felt achy muscles. I also went to the dentist for a regular cleaning and she asked me if I burned the roof of my mouth. I said no. She said “it sure looks like you did.” Well . . . I did burn the roof of my mouth on some French onion soup, but that was four years prior ! So I ate normally for the next three days, a the end of which I felt stuffed and wanted to fast, so I went back to my ADIF at that point, including my bike commuting to work and back. It was fine. I felt more energy, more alertness, better respiration . . . I really felt younger, for what it’s worth.

    • There are many ways to fast, and as many personal metabolisms you have to learn to manage. Longo talks about fasts on water, perhaps tea, and a spoonful of milk or sugar in the tea is not going to ruin everything. Under 50 calories a day is considered negligible. I often keep up supplements, including glucosamine and fish oil which could run to 50 calories.
      – Josh

      • Anything zero calorie is fine. I did a 7 day fast. I took water, tea, black coffee, even diet soda. I didn’t take any supplements, but I think Vitamin C and B vitamins are slightly depleted during a long fast. I took Vitamin C and a B complex on refeeding. When I do it again I would do a twice daily mouth rinse, probably with salt water, as a lot of mouthwash has alcohol and that can be absorbed buccally, and has calories. I had no problems really. I felt tired day 2 and day 7. By the second day of refeeding I felt back to normal.

        • Just FYI. I know it’s been a while since this was posted but most diet sodas contain artificial sweeteners which have been shown to be neurotoxic so I would say it is probably not a good idea to drink during a fast. Just my two cents.

          • Well, if Valter D Longo’s research is valid, your normal cells would be protected from the toxic effects during fast. So you should drink artificial sweeteners during fast only.
            I am very interested in any research showing that sweeteners have adverse effects especially aspartam as I drink a lot of it. Could you please share us links to those studies?

          • Aspartame is one of the most extensively studied additives . . . . they did find some people’s gut bacteria can metabolize some artificial sweeteners and produce some calories, but a very small amount and the one they found the strongest effect for was not aspartame. Water is best on a fast, but sometimes you need a little boost. Interestingly they say you can take alcohol, which has calories and it won’t kick you out of ketogenesis. I haven’t tried it though.

  12. Great post, and glad to read so many comments from others who’ve tried fasting as well. I’ve started to experiment with fasting myself with great results.

    What about an only fresh vegetable juice fast? Would this produce the same effects? Also, what supplements do you take on a fast?


    • I think any calories simply delay the metabolic changes that make fasting beneficial. If you are taking juice, you are on a juice diet, not a fast. You will lose weight, but you would likely not get the stem cell regeneration.

  13. Let’s keep in mind something else, of mice and men. The lifespan of a mouse is much shorter than the lifespan of a man. And a three day fast is a long time for a mouse. A wild caught mouse will die without food for three days. This is the big unanswered question, just what is the optimum fast interval for a human? And I don’t think anyone knows, but it would be longer than 3 days.

  14. Hi!
    I have read your page with much interest. I came across the eat fast and live longer program on tv a couple of months ago and was inspired to do a 3 day 4 night fast.
    I did one in September , and am redoing it this month as well.
    My last meal was Saturday night and I am doing the single packet soup, tea and water thing that Moseley did in the documentary.
    I came across this link and wondered if you have read it too?
    It kind of puts the whole regimen into question for me. I was hoping you could use your access to Longo to ask him about it. I have written to him about my first go at the fast but never received a reply (I know he can’t answer every mail).
    Your assistance would be much appreciated

    • Thanks for pointing to this link, Jimmy. I wouldn’t worry yet. Longo’s data is in humans and mice. Flies might be different. Of course, we might find something out later that will make us regret having fasted, but for now I’d say the preponderance of the data is very promising.

  15. Hi,
    I’m amazed by Dr Longo’s research. You’ll probably find my story a bit odd, but on September 4th the love of my life was diagnosed with cancer and as it would be for anyone I was devastated and felt helpless. I thought the only thing that could help him is the Lord’s healing so knowing absolutely nothing about the positive effects of fasting I decided to do a spiritual fast where I was drinking water only and praying for healing. On probably about day 10 or 11 my arm and leg muscles started aching all of them at the same time. I started to get worried that there may be something wrong with me since I hadn’t had anything to eat in such a long time. I started researching effects from fasting and started finding all these great stories and learned that the reason my muscles were aching was because they were releasing toxins. Then on day 13 I found articles about Dr Longo research and how effective it is with chemo treatment. I’ve probably read everything there is about Longo and cancer related articles and believe in it. I broke my fast on day 13 and the first bite of salad was incredible. I’m on a journey now trying to convince my partner to try fasting with chemo as I believe it’s the only way to get better rid of cancer. I’ve done a few more short fasts since the 13 day fast and I feel great, people ask me if I have new make up as my skin is glowing and looking younger us I don’t even want to go anywhere near junk food anymore.

  16. prostate removed 18 months ago, serious cancer
    after operation PSA was 0.001
    then 6 months ago it rose again every month: 0.10 0.11 0.12 0.13 and 0.20

    radiations said the doctor

    I decided to fast one week in september, result PSA dropped to 0.18
    one more week fasting in october and now psa is 0.14


  17. Take a look at the Natural Hygiene System. Herbert Shelton supervised during his life hundreds of fastings. Some of them longer than 30 days.

    He is the author of lots of books. Including six volumes on the Natural Hygiene System. Volume 3 is dedicated to Fasting And Sunbathing. Hi is also the author of “Fasting can save your life”. I can’t think of somebody more experienced on fasting than Herbert Shelton.


    The Hygienic System Vol III; Fasting and Sun Bathing
    Fasting Can Save Your Life

    PD: Sorry for my english.

  18. Thank you for the article. Very enlightening!
    I’ve just finished my first 3-day-fasting (only water and herbal teas) and I feel really good. Apart from being hungry from time to time, I didn’t feel dizzy at all. I’ve never been without food for even 1 day, so it was amazing that I could do it for 3 days in a row. I lost about 3 kilos as well, which is also nice. I am going to eat fruit today and tomorrow and then vegetables for a couple of days.
    My question is: A friend of mine has an auto-immune disease. Do you know of specific articles that deal with fasting and these kind of diseases?

    Thank you and keep informing us.

    • Thanks for your inspiring story. We support each other in good health practices when we share information and experiences.

      Fuhrman J, Sarter B, Calabro DJ: Brief case reports of medically supervised, water-only fasting associated with remission of autoimmune disease. Altern Ther Health Med 2002;8:112, 110-111.

      Responses are individual. Tell your friend to keep her optimism and be prepared to try a dozen things, one at a time, to see what works for her. Vitamin D has worked for some people with auto-immune diseases. She might also try the Chinese herb cistanche.

      Try treatments one-at-a-time, keeping careful records of response because memory can be deceiving. Start with things that are known to be safe and unlikely to have detrimental side-effects. No one remedy is likely, but trying many possibilities, you can expect success.

    • Take a look at “fasting can save your life” by Herbert Shelton

      And also “The hygienic system vol III : fasting and sunbathing” by Herbert Shelton

  19. I have some suggestions that may be helpful for some people with situations similar to my own. I have long adhered to a ultra low calorie diet with significant vitamin and mineral supplementation, similar to the ideas proposed by Dr. Roy Walford. The benefits are primarily aging and disease related. I am male, and the diet has worked as planned for 25+ years. When the Longo research came out, I decided to add occasional fasting to this because of the immune system boost that appeared to come with fasting. Trouble is, there is no fasting research that applies to people who fast but who also adhere to an ultra low calorie diet. So I want to share with you my experiences and suggestions.

    First, I tried a water fast twice, six months apart. In both cases, I could not get past three days. As I approached 72 hours, the body clearly was in stress, and I quickly stopped the diet. The first two days were without issues. It is the arrival of the third day where the problems start. Basically, with an already low daily calorie intake, the body is running on a very lean burn. There is no cushion. With people on a normal diet, they have a larger calorie cushion, and fasting for five days can be good for them. But with a long term ultra low calorie diet, that is not going to work.

    Second, I jog for half an hour every other day, taking a break on the middle days. When I fasted, I jogged on the first day of the fast, and the third day of the fast. That was a mistake. For both times I fasted, on the third day of the fast when I jogged, my legs cramped very badly, taking a few days to recover. I had to stop the jogging in the middle of my run.

    So, for anyone who is on a long term ultra low calorie diet, you are already getting many benefits. The fasting is not going to do much more, and it could hurt if the fast is too long. My suggestions for those on long-term ultra low calorie diets with regard to fasting are these. (1) Avoid stressing the body, and stop the fast ASAP if the body responds with stress symptoms. In general, consider three days the max for fasting. No longer, and maybe a bit less. (2) Avoid vigorous exercise while you are fasting. The body is already dealing with a lot when fasting, especially without a pre-fasting calorie cushion. The short-term energy consumption demands associated with exercise are not what the body needs at that time. The muscles will start to eat themselves. Wait at least 24 hours after the fast is over before resuming exercise. (3) Do not fast more than once every six months. Take it easy.

    These suggestions may not be appropriate for many, most, or all people. But if you are one of the ultra-low calorie dieters, my general view is to find an approach that is comfortable to you. None of this should be attempted without a doctor’s supervision. I have my doctor do a thorough blood workup on me yearly, and that includes tests for all the major vitamin and mineral levels. Adjustments with supplementation is needed as a result of looking at test results. It costs some money to do this, so if you are on a budget and cannot afford the tests, do not do this. Just try to eat healthy and keep fit.

    Remember the lesson of Dr. Roy Walford. He found something good with his research, but then he pushed it too far with his own body. He basically eliminated all fat in his body, leaving him with no calorie cushion at all. In my opinion, it backfired, and he died pre-maturely at the age of 79. The general rule is to burn the body at a very lean mixture, but not so lean that it stresses the body. Significant supplementation is a must. Fasting in moderation every six months can be a nice addition, but monitor yourself carefully, and do not overdo it. As soon as the fast ends, get the nutrients back into your system. Make sure you are back at an equilibrium state. Be happy. If you are not happy, do not do any of this. Do something else that makes you happy.

    I am not a medical doctor, and these suggestions are only for the purposes of discussion. They are not medical advice. These suggestions should only be considered seriously after consultation with your own medical doctor. Follow your doctor’s advice first and foremost.

    • I have no trouble fasting; I can do three days with ease.

      But exercise and fasting can get a little tricky, as it’s easy to slide into hyponatremia. On a water fast (or even more so with tea or coffee), you are still pushing water through your body, so your sodium levels will tend to fall. If you add exercise, especially sweat-promoting exercise, you will lose even more sodium.

      I make sure to eat some salt if I exercise while fasting. At one point I was doing a lot of hot yoga, and neglecting to keep my sodium intake up. The result? One evening I went into convulsions.

      I don’t think that a few days of water-only is dangerous at all. But water-only plus exercise, in the absence of salt, might get a little sketchy…

        • How much sodium should be taken on fasting days, and how many times per day?

          What about getting some potassium together with the sodium? It’s easy enough to take a small mixture of sodium bicarbonate (baking soda) and potassium bicarbonate. Potassium and sodium are the two main electrolytes and you would guess potassium deficiency during a fast might also be a real risk.

  20. I have MDS and am exploring ways to improve my immune system before I have to undergo chemotherapy again and stem cell transplant. I am interested in the fast. Do you recommend no food or is organic juice acceptable? Let me know this and any other information that might be helpful as I would like to avoid another round of chemotherapy! Thank you.

      • For me fasting failed. 6 months of one 3 to 3 /2 day fasts per month failed to produce evident improvements in WBC while platelet counts were worse. I am 70+ yr 65 kg M with MDS neutropenia. After 6 fast cycles base line CBC shows the same neutrophil level and lower platelet count. That is not a hopeful result. Nevertheless fasting did feel good so I may resume. Fasting with water I used trace mineral supplements. It is important to maintain electrolyte balance. Fasting induced WBC suppression may have led to a significant throat infection immediately following my last fast. So watch it.

  21. I have done ketogenic diets several times and fasting but only rarely. Many symptoms are the same as water fasting, but some are different. Perhaps the differences are instructive. First, I always use Ketostix in any restrictive diet or fast. The reason is that I don’t want to waste lean muscle. The woman who reported her arms and legs aching after 10 days was likely not “releasing toxins” but was likely catabolizing muscle. The use of ketostix allows you to monitor if you are going too deeply into ketosis. A moderate level should indicate that you are only burning fat. At about day 3 of a ketogenic diet is the hardest point, just as with a fast or with any diet, assuming you are not starting from an already calorie restricted level. That is, that liver and muscles are full of stored glycogen. This is the point when most people fail at diets: they never get into ketosis because the metabolic switchover from carb to fat burning is uncomfortable. At 3 or 4 days I start registering on the ketositx and the diet is easier. To make this stage easier I’ve found that it’s easier to start with a long aerobic workout, like a 7 mile run or 40 km X-country ski day. My layman’s idea is that this burns up the stored glycogen and I get over the hump faster. I can register on the ketostix in a weekend eating a lot of lean chicken, veggies and cheese and no carbs. It eliminates a full day of discomfort. Then I feel better and start burning fat as shown by the ketostix. I have read that ketogenic metabolism is efficient but limited in the speed with which it can convert fat. This seems to agree with my experiments with going out skiing while already lightly in ketosis: I go, I stop, I go, I stop, I can keep going if I go slowly, but no where near full cruising speed and a prolonged sprint is a good way to faint.

    I am also surprised at how little sugar it takes to knock me out of ketosis. A salad where someone has added a pinch of sugar to the vinaigrette dressing will throw me back. A sauce thickened with breadcrumbs, or any fruit juice will do the same. The ketostix will register nothing. I then have to go through the transition to ketosis again. Usually the easiest way is to eliminate carbs for a day. (Even in a ketogenic diet you consume a fair number of complex carbs, just a hair under what you need. You eliminate nearly all carbs only at the beginning for a few days to make the transition to ketosis faster.) Therefore eating a bit of sugar or fruit juice during a fast seems like a counter productive policy, at least if ketosis is part of your planned benefit.

    I would not be surprised if many of the benefits of fasting could be obtained by periodic ketogenic diets, but I would also not be surprised if there are responses that only come about because of fasting where no calories have entered the system at all. After all it seems to be a threat response. All the same I would be very interested to learn which of the findings Dr. Longo found with fasting might also be accomplished with periodic ketogenic diets which would be far easier for me and have the benefit that once over the hump I function pretty normally.

    Finally, a psychological comment: having the ketostix offers a bit of proof that I’m burning fat and that feedback makes the diet far easier. My self control is only such that without such proof and the encouragement I would have to be under sever threat such as cancer to engage in fasting when there is no feedback to tell me it’s working.

    • Mike Farr, what are the guidelines for ketone levels in mmol/L that would indicate protein wasting? Do you have any citations that discuss that issue, preferably studies?

      Careful on assuming that you will get fasting benefits on a ketogenic diet. Autophagy during fasting is triggered by two dietary inputs: 1) low insulin and 2) low dietary amino acids. Even a small dose of single amino acids has been shown in rodent studies to quickly terminate autophagy.

  22. Hi,

    I have just finished my 5th cycle of 3 day fasts since started right before >Xmas. I decided on this already last summer when I had read about the article.
    Beside the papers I could get access there are lots of interviews with Valter Longo that you can find on the net. Also the Longo team has patented both the cancer and non cancer treatment. Its a bit tough read for me, but what I got from it is:
    day 1. 50% calorie restriction with 50% of calories on that day must come from fat
    day 2-4. food consumption <200 kCal.
    Then realimentation.
    You can repeat it every 2 weeks to every 14 weeks.
    Longo team has also made a paper about low protein diet, but I find that paper weak (it is based on multi decase followup of people whose diets were categorized based upon one self reported 24 hour period).
    I would wait for more research on this. The low protein diet is very hard to keep imho. I tried it and i didnt feel good.
    There have been also 3 clinical studies made on humans that havent yet been published. These will be the ultimate must reads if/when they finally come out.

    The 4 diet is extremely hard to keep. I feel very tired on the 3rd 24 hours. I have two small kids and cycle to work every day10kms. I had to give up cycling on the last day.
    Hard to get sleep, too. Once in a month is doable I think.
    I also feel the immune boosting effects (though it may be chance as well)
    both kids and wife were down with fever cough headaches for a week or two, I only felt some mind unease. Then on my last fast I also got some cough and aches near my ear. It is immune weakening on the short term I believe and this is also in the papers.

  23. There is a new study:

    “Feast-and-famine diet could extend life” by University of Florida.
    presented in EurekaAlert

    While I’m not as good as you guys at fasting, I did experiment a bit with 18 hours.
    This is what I did lately for few days:
    eat in the morning @ 6:30 am then @ lunch 12:00 pm then not eating until next morning @ 6:30 am
    I do drink a lot of black/green tea without any sugar/sweeteners and water during day.

    And I do take MitoQ/Nicotaminde Riboside/Gerovital/Resveratrol/VitaminD/K2/Fish Oil/B12/B3 in the morning.
    Between breakfast and lunch I take Alpha Lipoic Acid/Acetyl-L-Carnitine/L-Carnosine/CoQ10

    Before bed I take Melatonin/B6.

    Blood pressure around +/- 120/77

    I feel quite good and I lost some pounds. I think this method is “manageable”, though I would like to
    figure out if I get the benefits of increasing SIRT 3 and SIRT 1?
    So per study above, probably I have to drop any antioxidants during those hours.

  24. So I’ve been trying this every month since August, aiming for 7 days, but usually quitting at 5. What happens at day 5? It’s definitely different. I feel fine till day 5.

    I made it to day 7 once.

  25. Josh
    I have been very curious about Dr. Longo’s work and the various studies he has done around fasting and stem cell regeneration; so interested I finally decided to take a shot at a 3 day fast, my first ever. I am nearing hour 48 and feeling a bit tired, harder to concentrate (systems engineer – computers and fasting don’t mix I think) and starting to wonder about a few things. Is Longo’s position that it’s 4-5 days with zero calorie consumption or are some (fewer than 50?) allowed? As well, with a ‘water only’ fast lasting 3-5 days, is electrolyte / sodium / potassium / etc. loss a concern? And lastly, I have read some about the negative impacts of ‘rebound binging’ and surges of insulin which leads me to wonder about the correct process of “re-entry” after a fast, even for short periods of 48 – 72 hours. Condensed, is water only fasting biologically / medically “okay” for most people during a 72 hour fast (with no concern around electrolytes, etc.), and what might be some proper re-entry paths back into “normal” eating? Just looking to make more educated decisions regarding the fast.

    Thank you.
    ~ Jeffrey

    • Good questions, Jeffrey. I can answer from me, and you might write to Valter separately, and please do copy his answers here.

      I just finished a spring fast of 4 days, and find the same experience that you do. Hunger is not an overwhelming problem for me, but my concentration and productivity certainly suffer. I hope you’re paid by the hour ;).

      Like you, I’ll have a bit of tea each day with sugar or milk, and about 50 calories is what I figure I’m getting. And like you, I have taken salt on day 3 (in the form of a bouillon cube).

      There are lots of opinions about re-entry, but I don’t know of any hard studies on the subject. I find I have no willpower once I start eating, so have given up trying to be moderate. I notice that I gain back all the weight I lose during a fast within a week of ending it.

      – Josh

      • Josh, you say that a little sweet in the tea during fasting is OK, even a little milk…that “50 calories is considered negligible”….
        Is the what Dr. Longo told you? Or is this just your own view? Please clarify.
        John David
        PS. Still fasting 5-6 days once a month….feeling great! And the twice a week fasts also on other weeks.

          • I do the same. I just wish I knew what Dr. Longo would say about it…but he doesn’t reply to my emails.
            It makes sense to me that it wouldn’t matter…I am very active during my fasting…probably burning 3,000 calories a day. So a little honey in my tea is not going to affect my bodies switching to fasting/ketosis mode in any way, I wouldn’t think.
            But I would like to know what Dr. Longo would say.
            John David

          • Two comments:

            Yes, it’s common sense that a trivial number of calories wouldn’t make any difference. But we could be wrong. In lower animals (flies and worms), the mere smell of food is enough to reduce the benefit of CR. Is this also true in humans? I have not seen evidence one way or the other.

            This is a new field, and Valter is out on the edge. Remember that you can’t do controlled experiments with humans, and it takes too long to wait for them to die, so you have to infer longevity benefits from indirect evidence. So I strongly suspect the answer to your question is, “nobody knows” and this is the reason I have not pressed Valter for an answer.

          • Well, Josh, here is our latest exchange on the subject of adding a modicum of sweet or whatever to what we consume on the fasting days…and in your case, the calories of supplements as well:
            John David on April 4, 2015 at 7:11 am said:
            Josh, you say that a little sweet in the tea during fasting is OK, even a little milk…that “50 calories is considered negligible”…Is what Dr. Longo told you? Or is this just your own view? Please clarify.
            John David
            PS. Still fasting 5-6 days once a month….feeling great! And the twice a week fasts also on other weeks.

            joshmitteldorf on April 4, 2015 at 9:38 am said:
            The “50 calorie rule” is just what I do – there’s no data behind it.

            John David on April 4, 2015 at 9:26 pm said:
            I do the same. I just wish I knew what Dr. Longo would say about it…but he doesn’t reply to my emails. It makes sense to me that it wouldn’t matter…I am very active during my fasting…probably burning 3,000 calories a day. So a little honey in my tea is not going to affect my bodies switching to fasting/ketosis mode in any way, I wouldn’t think.
            But I would like to know what Dr. Longo would say.
            John David

            joshmitteldorf on April 4, 2015 at 10:36 pm said:
            Two comments:
            Yes, it’s common sense that a trivial number of calories wouldn’t make any difference. But we could be wrong. In lower animals (flies and worms), the mere smell of food is enough to reduce the benefit of CR. Is this also true in humans? I have not seen evidence one way or the other.
            This is a new field, and Valter is out on the edge. Remember that you can’t do controlled experiments with humans, and it takes too long to wait for them to die, so you have to infer longevity benefits from indirect evidence. So I strongly suspect the answer to your question is, “nobody knows” and this is the reason I have not pressed Valter for an answer.
            Well, I wrote again to Dr. Longo about this question, just this morning…and he was kind enough to reply. This is what I wrote to him:
            Dear Dr. Longo,
            Since I read your recent research, I have been fasting once a month for 5 days… for about 8 months now.
            I drink mostly water, but also a litre or two a day of herbal tea sweetened with a little honey.
            Does the honey in the tea I drink during my 5 day fast…maybe 100 calories a day…does that disqualify the effectiveness of the fasting?
            I would GREATLY appreciate knowing what you have to say about this.
            Thanks so much for your amazing research!
            Dr. Longo wrote back:
            hey david
            it will probably reduce the efficacy but not eliminate it
            And I wrote back to him:
            Thanks so much, Valter. If there is a chance it might reduce even a bit of the efficacy…there is no point in using it. Why put at risk even a bit of the efficacy of fasting five days…for a bit of honey? There is too much at stake.
            I really appreciate you responding…I know you must get a huge number of such queries.
            All the best,
            So for me, Josh, this settles the issue. I should mention I said “100 calories” instead of 50….because I think is likely I may be underestimating my fasting calorie consumption if I said 50. And I very much doubt that his answer would have been any different if I had said 50 calories instead of 100.

            I have fasted for the past eight months…feeling free to go ahead with a little honey..and like you, even a little milk in my tea at times…because it made sense to me that a few calories would make no real difference. But honestly, I felt a bit uneasy about it also…because what is the point of going to such trouble as fasting five days a month…and missing out on the best possible outcome…for a sake of a few calories? I thought it possible I might be outsmarting myself once again….by just going by my own judgement…but I hung onto my assumption you were doing and saying what you had heard from Dr. Longo…because, honestly, I LIKE a little honey in my tea…even when fasting.
            I should say that your statement that “50 calories is considered negligible”….when that is your own judgement exclusively….that is a little misleading, don’t you think? The language you use is that of someone (it seems to me) who is stating a fact they heard from some other authority on the subject…and it would be natural to assume you heard this from Dr. Longo. It would have been a bit more clear to state it something like, “Personally, I consider 50 calories to be negligible”…..don’t you think?
            But knowing now what Dr. Longo has to say about it….for me, it is zero calories when fasting from here on out. I want the best possible outcome…and don’t want to put that at risk in any way.

            All the best,
            John David

          • I suspect he (Longo) doesn’t want the legal liability of saying something, then having someone hurt themselves or die on a fast due to a medical condition.

        • It depends on your muscle mass and activity level.

          Men have more muscle mass than women, which is why they go into ketogenesis on day 3, and women on day 2.

          It’s easy enough to test if you are in ketosis by using Ketostix (any pharmacy will have it).

          A ketogenic diet is anything under 50g of carbs a day, but I know people who can go up to 90g and stay in ketosis. Again, it really depends on you muscle mass and activity level.

    • refeeding syndrome is only of concern on fasts 5 days or longer, which you should break gradually, starting with fruits. google “refeeding syndrome”

      I think the body has to be in ketognensis to get the benefits of prolonged fasting, so don’t take in any calories, especially sugars or carbs.

      vitamin C and B vitamins start to deplete on a longer fast, but taking vitamins or minerals may negate the effects of fasting according to some recent studies. the same effects are observed wrt exercise and taking antioxidant vitamins.

      fasting is a like exercise. you can’t run a 26 mile marathon when you first start, but your body will adapt over time. I have great mental alertness on days 3 and 4 now, which I look forward to now.

  26. I am on Day 3-1/2 of this fast to improve my own immune system because a urologist found cancer starting in my bladder and I became dangerously intolerant to a treatment designed to generate a targeted elevated immune response. I’m not on any medication. It would be nice to get a good report from my next bladder inspection in May. My regular doctor knows I’m trying this fast and has not said I shouldn’t do it.

    After 17 months on Dr Fuhrman’s “nutritarian” food plan, blood pressure has normalized for my age (86) without medication, atrial fibrillation has subsided, but the anti cancer factor could use a little help. At 5ft 10in and 148lb I don’t need to lose weight.

    I wonder how fasting affects a biome deprived of food and fiber. I haven’t had a bowel movement since the day before starting the fast. Is that normal?

    I’m hungry!!! Can I chew sugar free gum? Yesterday I had 1/4th of a prune and realized that wasn’t tolerable. Today, I sipped 4 oz of weak limeade (juice of one small lime added to 32oz of water) and that seemed OK (like herbal tea, I rationalized). Otherwise it’s been 48oz (that’s three 16oz glasses plus as much of the 4th glass as I can stand) of plain water a day plus a couple of small cups of herbal organic roasted dandelion root tea. Water alone after Day 1 leaves me weak and wobbly.

    I’m trying to walk 2 or 3 miles a day, leisurely. I sleep OK, but still tire toward late afternoon.

    Any suggestions?

    • Dear Phil,
      Thanks for telling your story. You are stricter about your fast than I have been. I allow myself tea and even a little lemon or (gasp!) milk in the tea. I encourage you to find a regimen that you can live with.
      A cancer diagnosis is a big wake-up call that changes your life in all sorts of ways. I admire your steadfastness in not going the chemo route, and I trust that you are in touch with a doctor who can provide a credible alternative. Your doctor might suggest herbs or supplements you can take to knock out cancer cells at this point, when their vulnerability has been greatly increased by your fast.
      Advanced age is actually an asset in dealing with cancer. I hope you’ll continue to let us know how you’re doing.
      – Josh

  27. Do the future generations of the cells that don’t commit suicide, commit suicide under starvation conditions? If not, does this mean fasting becomes less effective when repeated? Of the people who I have read about who fasted a lot, they stayed relatively healthy until they died, but they didn’t live extraordinarily long lives (80s/90s).

  28. Nice find!

    I am an adult male who has been morbidly obese for years. This past March I went to the doctor with severe abdominal pain and fatigue. His office called me on March 9, my 63rd birthday, and said my blood work was all normal except for glucose, which was 195… just shy of an “official” Type-2 diabetes random glucose test number, but the doc called it diabetes. I began to stab my finger 4 times daily and the numbers were high all the time. No fluke – I am diabetic.

    I began a low-carb diet – eliminating almost entirely all refined sugars and starches – and have dropped just shy of 40 pounds in the last three months (286 down to 247). I kept a spreadsheet of all the blood tests and ran trend lines and charts to track my progress and my glucose levels have steadily declined over this time from around 150 to about 120. I feel great now, even though there was a time when I began to have unexplained severe middle back pains and incredibly dry hands (I have never suffered from dry skin). The back pains have diminished and my hands have healed themselves. My skin in general looks much better, as if I went back 20 years in age. None of my clothes fit, but I am wearing them anyway as a reminder of what I used to be like.

    Recently I felt I was hitting a plateau with both the weight and the blood sugar, and I started Goggling what else I could do to continue to improve. I came upon the work of Dr. Jason Yung from Canada and became very interested in fasting. Today was the first solid food I ate in over 48 hours. I felt hungry, so I had some blueberries, strawberries, and cherries, followed by a bowl of miso soup with garlic scapes and shittake mushrooms. I came across this site after a link that led me to Dr. Longo’s work, and then further searching brought me here. I am nervous about going too much further than this at this time, but may start fasting a couple days every week. My daughter suffers from many autoimmune disorders, so I am trying to find out more about the 4-5 day fasts. All searches on stem cell regeneration due to fasting have led me to Dr. Long’s work, but I plan looking deeper into PubMed for what I can find, and I will report my results back here.

    Thanks for maintaining this blog, Josh. It is helpful to talk about all this. Friends, family, and Facebook acquaintances all seem to have little interest in all this, so this may be a good place for me to visit.

    • Daniel, your story is inspiring.
      My fondest hope is that we can be a community for one another, sharing not only our knowledge but the courage it takes to change habits and to care for ourselves well.
      – Josh

    • I think you meant Dr Jason Fung. He recently published “The Obesity Code”. It’s a fantastic read! He explains why diets never work for weight loss. Interesting stuff on fasting/eating. Interestingly, I have been on intermittent fasting for about a half of year. I try to eat nothing after dinner around seven until the next day about one or 2 o’clock in the afternoon. This seems to be pretty easy for me. I have some coffee in the morning with a tiny bit of almond milk. I did the 72 hour fast a couple of years ago because that’s what I thought was recommended for the “reset” of the immune system. Now, it seems like it’s supposed to be four days or longer? I’m unsure now. Good luck in your endeavors Daniel! You might find Fung’s book a good read. There are also a number of videos on YouTube just search for Jason Fung.

  29. Dear all, last week I started a 5 days water fasting and I want to report here some considerations and questions.
    Also thanks to your valuable contributions here fasting days went very well. I drank a lot of water, only 1 cup of green tea (Decaffeinated by hand) in the morning and magnesium as supplement.. I was at my home, no working, I did some yoga and meditation and walking, but in any case I have some small children so I could not dedicate totaly to fasting. I felt especially weak on the second and third day. In the last two days I had as side effect hiccups. I know a little moxa treatment and so I treated with moxa the points related to low pressure. My glicemic index at the fourth day was 52 and at the morning of the fifth day was 49. I am 41 years old and I am tall 1.81 m and my initial weight was 73 kg. At the end of the fasting I was 68,9 kg ( I lost about 1 kg every day).
    Now the questions. the second day after finishing the fasting I measured glicemix index and it was 89! the day after still higher: 104. I usually have an average of glicemix index of 85. What happened? In both the nights I slept only a very few hours, so I am thinking that the raise of glycemia is due to the poor sleep…. or could be that it exist some rebound effect? I mean, glycemia goes down and then up faster…. Actually I think I haven’t started to eat again with the needed caution. I stopped the fasting with dinner having miso soup and some zucchini steam and carrot juice, but the day after maybe I have eaten to much brown rice… This led me to have constipation. I understimated the importance of refeeding with caution only with vegetable soups and juice. In any case Tthe overall experience was very interesting.
    I am reading the interesting trascripts of this conversation with Doctors Longo, Mattson, Mosley: “” Regarding the 5 days Longo says that “the problem is the safety concerns of most of the panels that review clinical trials. So they — so far, they allowed us to go to five days, up to five days”

    • A couple of comments. I am a 70+ YO M about 64.2 kg and no diabetes issues. I went for 6x 3 day and a few hours fasts spaced at monthly intervals for 1/2 year. I had cramps and bought potassium pills. I also usually used a non caloric general mineral supplement. Black no sugar coffee was allowed in the clinical trials so I allowed myself coffee. Each fast was a different experience. The last one went almost 4 days and I felt it could go longer. It is a good thing I didn’t. I got an infection and cold shortly after ending the fast, I presume before much recovery set in. I did not prove the fasting worked as advertised. Blood readings did not indicate reversal of slow decline in immune system function. But I will do it again anyway. It felt good.

      • Hi there. Very interesting! 6 months. My interest lies in anti-aging. I wonder what the surplus rate of repair is and if that does lets say have an anti-aging ability, then the mathematical question is simple: how long would it take (doing intermittent fasting and feeding) to say reverse aging by say a year? Two years? 5 years? Etc.? You have done this consistently for 6 months. I wonder if at the end of the day this is a math problem? Wishing you continued success. I would love to hear any follow ups via e-mail. Cheers. Rob

    • Eugenio,

      when you say glycemic index do you really mean blood sugar readings? You know testing your blood sugar with a glucometer.

      • Hello Lezlee, yes, I have used a glucometer for the glycemia measures in mg/dL.
        I was really surprised of the high rising of the glycemia after reefeeding. I haven’t yet analyzed the data in the Longo’s article to see if it exist some “rebound effect” after refeeding.
        Otherwise the explanation could be the poor sleep I had in those two days. Now I know that 5 days of fasting are engaging, you need time to rest whenever you need during fasting and also a quiet environment during the first days of refeeding.

        • I think glucose intolerance (elevated blood glucose) is widely reported in caloric restriction. Your readings are still within healthy limits. I guess you measured fasting glucose before breakfast.
          Actually the reading of 49 seems a bit too low, not the 105 too high.

  30. Hello Gabor, thanks , yes I measured the fasting glucose before breakfast. Regarding the the reading of 49 mg/dL , I read somewhere in one of Longo’s article that at the end of the fasting, the glucose in average decreased of 30%…I would be curious to know (if) at which concentration arrived the keton bodies that day…

  31. hi Josh

    I’ve found your recipes for the 5 day fast mimicking diet to be quite valuable. I’m just ending my 3rd month fast diet and will do my second set in March. I’ve noticed that some of Dr. Longo’s test subjects did a different approach, fasting 4 days in a row every two months. Do you have any knowledge about whether this is an acceptable alternative to 3 months on, three months off? Thanks

  32. in my third day of fasting at nature cure facility near hyderabad india.
    have observed this place for 35 years now.
    25 years ago had undergone fasting for 21 days to get rid of my allergies and bronchitis.
    fasting here means 5 times honey lime water.
    it works wonders.

  33. I read the article in June of 2014 and did a 72 hour fast starting that same day. I did it because I was getting sick 5-6 times a year. I have kids and would get anything anyo of them brought home. I had seasonal allergies too. I was sick of getting sick and was willing to try it. It was tough with stomach growling and psychological need for food. The second nights sleep was also horrible. I did it for 72 hours though and the more time that went on the better I felt. I actually felt like I had mental clarity. 9 months later I hadn’t gotten sick once and my allergies were negligible. I fasted again for 72 hours in March of 2015. That time was easy peasy – no problem, probably because I knew what to expect. It is now 1/25/16 and I still haven’t been sick since before I fasted in 6/2014, despite constant sickness at my house amongst my family. I am now in hour 21 of my next 72 hour fast and a firm believer in the power of this. I’m tempted to go longer than 72 after reading this blog, but I have had great success with just 72 hours so we will see. It works!

  34. Concerns me to see a lot of people here with active cancer tumors doing this. It explicitly states that the immune system is suppressed during this process. Your white blood cells, which actively kill tumors, are reduced significantly when you fast. It seems to me this is the opposite of what you would want. A non-fruit, vegetable juicing fast would make a lot more sense to me for someone with cancer, than fasting altogether and suppressing your immune system. It’s thought that it’s the absence of sugar that kills the tumors. Not the absence of an immune system. I realize you may have a healthier immune system afterwards, but I don’t know the people with active cancers should be taking this risk. Just thinking out loud here.

  35. What is Valter’s logic for why a 4-to-5 day fast is minimum / ideal for humans? The body goes into autophagy sometime around 20 to 30 hours into a fast, so why wouldn’t a two day fast done maybe twice a month also give a good result?

      • The image you posted shows a barcode together with the word “freedom”. Are you trying to link to a graph from a study?

      • I don’t know the answer to that, but on my two water fasts (3-day and 5-day), my psoriasis was greatly reduced and the psoriatic arthritis symptoms disappeared on the third day (both times). I go into ketosis within 24 hours, so the improvements didn’t seem to be directly related.

        The two water fasts, plus a strict, high nutrient, vegan diet are helping my autoimmune conditions. They may go into remission at this rate. I will continue doing the water fasts about once per month.

  36. 60 Year old male. In 2011 I weighed 255 pounds…and got a wake up call in the form of getting a real bad case of the flu. Since 2011 I have been on a low-carb diet along with heavy exercise (bicycle/weights/body weight exercise) that 2 years ago transitioned to a Very Low Carb High Fat/IF diet. Been eating one meal a day during the work week and working out fasted prior to dinner. Had a set back when I blew my knee out doing squats with weights about 8 months ago. Before my set back I weighed 195. March 10 had ACL reconstruction and about 3 weeks ago started working out again…feels great. I am surprised that I was able to build muscle and actually got very strong…100 push ups in 5 minutes etc.

    At the start of June I completed a 86 hour fast. Working out twice during the fast (10 mile bicycle ride/100 push ups/pull ups/core exercises).

    Just broke a 66 hour fast worked out twice during the fast. Same regime.

    Fasting when you follow a diet that has you in low ketosis most of the time is easy…I just got bored and I really enjoy eating.

    Amazing how hyper I got as the time passed. I actually felt energized. Meditation was amazing.

    If you have not tried IF and exercise I heartily recommend it. And the multi-day fasting feels wonderful and will probably become a monthly regime.

  37. This seems particularly interesting.

    PF cycles lasting 2 or more days, but separated by at least a week of a normal diet, are emerging as a highly effective strategy to protect normal cells and organs from a variety of toxins and toxic conditions (Raffaghello et al., 2008, Verweij et al., 2011) while increasing the death of many cancer cell types (Lee et al., 2012a, Shi et al., 2012). PF causes a decrease in blood glucose, insulin, and insulin-like growth factor 1 (IGF-1) (Lee et al., 2010) and is accompanied by autophagy (Cuervo et al., 2005, Madeo et al., 2010). Recently, we have shown that PF causes a major reduction in the levels of white blood cells followed by stem-cell-based immune system regeneration upon refeeding (Cheng et al., 2014). Others have reported on the role of PF in causing major decreases in liver and body mass in rats (Wasselin et al., 2014).

  38. Hello I have been doing the every other day diet to lose weight and potentially get the benefits of autophagy. So far I have lost about 10 lbs in two months and gained muscle mass i didn’t have before. I work out 3 days a week heavy lifting on my feeding days. My curiosity got me here as I’ve had a 4 day cold sneezing, faucet nose, ect. And I had assumed that this style of eating were to give me some type of immune protection. I was curious to know if there are any studies showing the benefits of doing every other day 24 hr fasts vs 4day fasts? Or if anyone here had switched from a every other day 24hr fast to a regimen of 4 days a month and noticed a difference between the two. I am going to start fasting 5 days a month for the next couple of months in Oct 2016 and see after two months any type of improvements.

    • Lane – thanks for reporting your results.
      I say this often: Studies on humans present us with broad averages. You don’t know what experience you will have because your metabolism is unique, and even then our conditions vary from day to day. There is no diet that will guarantee you don’t get a hum-dinger of a cold every once in a while.

      I have been in Beijing for 6 weeks. I am taking metformin, which I have been warned may weaken my immune system. The pollution is higher than any American city. I expected to get some kind of cold or flu or at least the runs. But I have been completely healthy since I am here.

      – Josh

      • NM
        I was doing 3day fast every week for 1.5 years
        Resalts were amaizing; inflamations are gone, did not get sick, lots of energy, clear mind weight loss
        Now i do 2 day(48 hr) fast every week
        Agree that 48 hr is enough for women, and most important what you eat between fasting days
        Ketogenic diet is the best- that is my experience.

    • If you read the animal model studies where Valter Longo was lead author, you can see that neutrophil count was suppressed after the fast took hold. I found the relevant figure in the relevant paper after I took I’ll after a 4 day fast. Since my neut count is suppressed to begin with my risk may be higher than normal. There may be good reason to keep to a 3 day once a month cycle. By the way, weight loss is a different objective. I would not mix modes.

  39. Hi, I am a 72 year old lady. Recently I developed gout in my right foot. After taking the conventional drugs for it, with very little relief, I have decided to water fast for 3 days to see if I can reduce the inflammation. I had a lot of pain in my left leg, making it very difficult to walk. Even though I eat a mostly vegetarian diet with a little fish, I feel like I have a lot of inflammation in my body. Has anyone here had success reducing inflammation with fasting. I am on hour 21 of the fast with a small headache and some relief in my condition. Thanks for all that contribute to the blog.

  40. Thank you all for sharing your insights, stories, and experiences. Has anyone tried fasting and had success with ‘alopecia’? Hair loss, which is also an auto immune disease and medicine has no cure other than cortisone.I decided not to use cortisone and I tried a 4,5 long psychoterapy bec it is said to be triggered by stress. 3 years bold all over the body including all kinds of hair (ears, nose….) my hair came back all over the body except under my arms (which is appreciated:), but I am loosing batches of hair constantly.
    I will try the fasting…But would appreciate any personal experience…


  41. After researching all the benefits of fasting, I’m ready to try it. I have been following a low carb diet and am mildly in ketosis while I am in the first stages. I do drink daily though which is a bit of a problem. Under alot of pressure and stress presently. Feeling very tired and sick and problems with alot of pain and energy loss. So my question is: should I taper up to fasting? Start maybe skipping lunch or a dinner and just drink water, then work up to skipping 2 meals, then to 3, until I can do it to the 3 days? Or should I go straight for the 3 days. Wondering how quiting alcohol consumption and fasting will feel? BTW I am 58 yr old woman. Been in relatively great shape until this last year.

    • Barbara –
      The answer to this has to be personal – what are you ready to take on? Talk to friends and family, get commitments of support. Make a modest plan and stick to it. Then decide what to take on next. You are the best judge whether it will work for you to cut alcohol and food at the same time or at separate times.
      – Josh

  42. If eat within a 5-6 hour window daily, then fast Fridays, which turns into about 42 hours. Over the Christmas holiday I did a 92-hour fast, and just completed a 72-hour fast a few days ago. I noticed on the longer fasts a lift in mood, a positive (admittedly subjective) change in skin tone. Similar to what you mention, I found the experience calming. After breaking the fast, I felt a bump in overall health, both physically and mentally. Like Santiago in an above post, I’m interested in whether Dr. Longo has an opinion on frequency of these longer fasting periods for a generally healthy adult.

  43. Has Dr. Longo or anyone else considered whether exercise could be used in conjunction with fasting to reduce the 3 – 5 day immune resetting period to a shorter period? (I am guessing that exercise plus fasting intensifies the fast vs fasting alone)

  44. For anyone on a long term fast I would not recommend any supplements containing coffee berry. It stops (or slows down considerably) gluconeogenesis and can drop your blood sugar to dangerously low levels. I would also recommend to check your blood sugar frequently to make sure you’re not dropping below 50 mg/dl. My own blood sugar will stabilize ~55 mg/dl after day 4 or 5 and won’t drop below this no matter how long I continue the fast. However, I recently went on a long term water fast but took some supplements, one of which contained coffee berry and it dropped my blood sugar to 37 mg/dl. I immediately broke the fast and felt better afterwards and my blood sugar returned to normal.

  45. Three years ago, I was diagnosed with idiopathic neutropenia and had to start seeing a cancer doctor because of it. We did the usual cutting out of the natural
    herbs and supplements I take with no response, just continued numbers falling, with small upticks as I made other nutritional and exercise changes. I have researched Valter Longo’s work because of this specific blog post and finally decided to bite the bullet and try the four day, water-only fast. I am commenting in hopes that others who didn’t have the plenty of energy/no-big-thing reaction others are stating will see another facet of this. As you have said, we all are contributing to gain enough insight to decide what to do with the information.

    I want also state something to give context: I have fasted before for my faith tradition, believing that my fasting was having good unseen impact. I did the Spartan Race 4 years ago. I have broken multiple bones in my body. I have built a nutrition product and coaching business that helps provide for my family, and have homeschooled 5 children into successful adults. All of these have required extreme discipline, self-denial, and self-awareness to stay healthy emotionally, physically, and spiritually. I am not a whiner, and I am not a wuss, and I don’t cheat.

    At 22 hours into my fast, my head started hurting so badly that I had to go home from the event I was at and sleep basically through to the next morning. Because I woke up feeling weak, as expected, I treated myself gently and did not do our planned outing that morning. (Thanks for your words about your weekly Thursday fasting to help me feel better about this decision.) I spent all the day feeling nauseated and headachy and having hot flashes by turns, which my nutritionist training keyed me in that I might be having blood sugar issues, and I got out my Accu-check blood draw system that I use for my clients, and started recording my sugar to make sure I was within range at all times.

    When I awoke the next morning and got dressed and went downstairs, I had a bad blood sugar drop that had me hot flashing, shaking, and mentally compromised. There was discussion in this thread that involved a 50 calorie limitation, so I sipped 6 ounces of Gatorade (40 calories–the only thing I could think to consume) and it went back up and the symptoms resolved. I almost ended it all because of that incident, but I knew that I just had eight more hours to be at 72 hours and I hated to see all my hard work, sacrifice, and discomfort not be fulfilled and impact my white blood cell count for the better.

    At that point, because of this blog article comment thread, I had my daughter go out and purchase ketostix. It keeps being said here that women only need 48 hours, and I am of good health and weight, but I wanted proof that the ketosis was happening because the glycogen was used up, which I understand from the reading is supposed to start the stem cell activation and cleaning out of the debris/weaker cells. I wish I had started tracking that at the onset of the first headache and throughout, so I could make a more informed decision of when to stop the fast.

    I chugged through and ended 3-1/2 hours shy of a full 4×24 hours due to another confirmed episode of hypoglycemia. I had only consumed over that 4 days 2×6 ounces of Gatorade (1 each during hypoglycemic episodes), 1 cup of tea with stevia only, and 1 cup of coffee with stevia, and generous amounts of water. I eased back into a normal diet, and 5 days after breaking the fast had my regular 6-month blood draw for my condition. Unfortunately, I am now lower in all numbers than I was at my reading 12 months ago.

    I don’t know if Mr. Longo would have further input for me, or be able to place a finger on any error I made. I am just relaying data about my experience. Had the results been different, I would have decided to pursue this further, but with my apparent predisposition to hypoglycemia, I am not likely to place myself in this position again without better monitoring. I feel it is extremely important that people understand that every body is different, and these wonderful testimonials–which I was fully expecting and anticipating being a part of and excited to have the lab results to prove it–need to be tempered with knowing your own limitations and tweaking to keep you healthy.

    Thank you for this terrific blog and information.

  46. Well, it’s a long time since you first wrote this blog. Are you still fasting? Have you found any great results. On my part I’ve maintained a fasting regime since 1990. I’ve done 1 day fasts – 3 days – 5 days – 11 days.

    Originally, I was suffering from seasonal allergies, my eyes were so itchy I wanted to pull them out and wash them. It was horrible. So, I fasted a day. That helped, but it did not cure the allergies, then I fasted for 3 days and that did it. I juiced and kept a clean diet, fasting intermittently for prayer (I’m a christian), for health, to lose weight, to gain control of my appetite. Fasting has done me a world of good. I am 56 and look about 10 years younger, though some say I look even younger then that, but mind you, I’ve been juicing and keeping a pretty clean diet. I go off and have to reboot and fast again, but it always does the same for me. Helps tremendously.

    Presently I’m doing a 3 day fast because the allergies came back. I’m not one to take pills for anything, so I am fasting. I’m in the second day and already, my eyes are clear, I am not sneezing. You see, allergies are an immune response, the body thinks it’s being attacked as if germs were attacking. I reasoned, long ago, that this could only be because my body is so toxic that it cannot discern what is a germ and what is not. Therefore I fasted. BUT remember, going off the fast I will juice, eat organic produce only, and maintain my exercise routine. There’s a lot to living a healthy lifestyle fasting can help.

  47. Don’t know if anyone is still following this blog.

    Longo is working on putting data on his “Fasting Mimicking Diet” in front of the FDA. He is hoping Doctors will be able to just prescribe it. I think he is working on a pre-chemo indication, but once approved on safety it will be easy to try for other conditions.

    In contrast to what some other researchers have found (who believe water only has the best data), Longo has found benefits with a 5 day. Essentially the 5 day fast is the equivalent of eating a medium avocado twice a day. As many have noted however, the biggest thing to overcome in a 5 day fast for most people is fear of not eating.

    The other thing to consider is what your objectives are for your fast. 3 days can reset your glycemic response, and put you into ketosis well enough to maintain with a ketotic diet. 5 days for pre-chemo. 5 days likely to get serious autophagy. But human studies are limited. Important to note for anyone reading the animal literature, 48 hours is a very long time for a mouse to fast – losing almost 1/2 their weight- and not equivalent to a human 48 hour fast.

    I’m curious about the collection of anecdotes on dermatitis and allergic conditions. Did that ever come to fruition?


  48. Have done three or four three-day fasts in the past two years. They help to reset eating habits when I stray toward evening snacking and to resize me into the clothes that make me feel most comfortable. On day three of a fast now, with the intention of moving on to day four — perhaps a half-day beyond, I am fine, especially when I stop thinking about the pleasure of food (not hunger, however, which interests me considerably).

    A type II diabetic, I eliminate Metformin during fasts, and my blood sugar always drops to much more reasonable levels than I typically manage while eating and taking Metformin. It hit levels, after 48 hours this time, of 97 before bed and 109 after rising. Afterwards, I return to Metformin and it seems easier to eat more sensibly and manage my blood glucose better — A1C dropping from the 6.1-6.2 range down to 5.7-5.9 after each fast, and staying there until I begin to inch away from the best habits and repeat the fasting process to help me maintain better health.

    Following a fast, I find easily discernible benefits. Simple salads appear to have an augmented flavor after being away from food during fasts. Indeed, everything tastes richer. Energy levels increase, and my overall sense of well-being improves. I seem to be bothered less by casual illnesses, like colds.

    Not necessarily a benefit, but a difference: Time appears to move more slowly during fasts; days begin to take on a dreamlike quality by day three, along with an almost paradoxically increased focus which I find striking. An increased sense of mental clarity initially survives the fast, reminding me to work at sustaining that clarity without the deprivation that enabled it.

    Whether or not any of this translates to a rebooted immune system or other payoff, I have hope. In the meantime, occasional fasting offers something of value to me.

    Of note, I reduce or sometimes eliminate a daily habit of 3.5 mile walks as I progress through a fast; my physical energy levels seem to drop as fasting time increases, but it rebounds quickly enough when eating resumes.

    This thread is growing as old as it is long, but I post to keep it alive, if only for while longer. And that’s what we’re all striving toward, one imagines.

    Anyway, I appreciate this blog and the fascinating posts contained therein. Information is the best tool we have to use against all the human ills that lie in wait.

    • Thank you for your experience. I’m on day 2 today, and climbed a rugged mountain trail, about 800 feet up, but slowly. I was winded every few steps. My plan is to eat tomorrow night, but who knows? I’m past hunger, but slowed down, mind and body.
      – Josh

  49. Ok, I have a different story to tell. And I’m looking for explanations please – I’m baffled!
    Im on day 4 of a water fast. On 2 days I had black coffee in the morning, otherwise only filtered water with small squeeze of fresh lemon. I feel terrible! Each day worse. Nauseous, and feeling really heavy and tired. Last 2 mornings really dizzy. Foggy head, hard to focus. Early on had headaches, not the past 2 days. Waves of intense hunger, but today I can’t even think of anything I’d like to eat- all seems gross.
    I’m 62. Live a very healthy lifestyle including daily yoga and meditation, and mostly eat loads of raw veggies, nuts and seeds and and quinoa, some fish and meat, sometimes good quality cake/pizza/bread. And eat mostly in a 8 hour window (11-7). I’ve also often done 24hr fasts with no difficulty.
    And, my 28 yr old daughter is doing this too and having a very similar experience!
    She also lives/eats healthfully, but probably under a lot more stress. She’s 5’8″ and around 135lbs. I’m 5’6″ around 125lbs. I’m doing the fast to reset the immune system because of Hashimotos (thyroid) issues, she to clear up skin issues (acne).
    Oh yes – I’m in the UK, she’s in California. And I make a point to text her asking how’s she doing before I tell her my story of the day (I’m 8 hours ahead). Haven’t wanted to contaminate her experience by telling her mine first.
    Anyone have any idea what’s going on? Shouldn’t we be in ketosis now and feeling good?!

    • Sarah –
      Don’t create a painful experience for yourself. You’re right, it’s not supposed to be like this. Bodies go through all kinds of experiences, and this may not be the right time for a fast. You can try again next month.
      If you want to try one more thing first before abandoning the fast – perhaps an enema. Sometimes I’ve found that that helps. Coffee or epsom salt enema gets the gut moving again.
      – Josh

    • Personally, I would abandon the fast after three days in your situation. Some people can go longer. But I find that three days is max. (I am thin.) Once the body feels like it is tearing itself apart, it it telling you something. You are already thin, and you don’t eat a lot of junk food. So your body is already primed to do well. Cut the fast after three days, and eat healthy food to break the fast. Someone who is much heavier may be able to go 20 days with water, since there are lots of reserves to go through. But people who already eat few calories per day don’t have this ability, and shouldn’t have this ability. It is normal. I would not try the enema idea. You are only going to further stress the body. If you have Hashimoto’s disease, then simply follow the doctor’s orders and take levothyroxine at the prescribed dosage. Don’t try to fix that with a fast. That is not what the fasts are for. I am not a doctor, but I do advise that you follow your doctor’s advice. Do not try to fix Hashimoto’s disease with a fast.

  50. Dear Josh, I was diagnosed with Addison’s Disease (auto-immune disorder where both adrenal cortices are destroyed) in 2016. My body no longer produces cortisol – which, apparently, one can die without. I have to take a steroid (Cortef) and have gained 50 pounds. I am desperate to “reset” my immune system and get off this horrid medication (which robs the body of bone density and creates vision problems just to name two of the side effects). However, I must avoid going into adrenal crisis (where I start vomiting profusely and am beset with extreme nausea, weakness, and fatigue). I want and need to be healed completely. Addison’s Disease patients are classified as “salt losers”; as such, I have been consuming 16 teaspoons per day of “SOLE” (Himalayan pink salt and water immersion) with organic green tea and organic lemon. I have been taking an organic grass-fed/grass-finished organ meat complex which has helped my energy tremendously. In reading some of the comments above, it bespeaks eliminating minerals, vitamins, enzymes, and the like when fasting. I am honestly not sure if I “can” fast 4-5 days because I’m “afraid” I will get so hungry I become nauseous and throw myself into another adrenal crisis. However, if fasting can completely “reset” my immune system, I would like to try it. To be clear, when fasting, can I drink the “SOLE” ? The HP salt obviously has lots of trace minerals, etc. Also, one of the first things Addison’s patients are told to do when they feel like a “crisis” is coming on is to consume SALT. What are your thoughts about this? Thank you.

    • hey don’t worry… I followed a 5 day <800 calorie diet.

      eat meat & fats for 2 days before the fast so that you enter ketosis faster. then, start your valter longo style diet for 5 days.

      the first 3 days are still a pain, on day 4 and 5 you feel great.

  51. Autoimmune disease can go into remission, many functional medicine doctors prove it like Dr. Terry Wahls, Dr. Mark Hyman, Dr. Amy Meyers. I learned so much from reading their books on this topic. The research of Dr. Fasano is often quoted and very powerful. The challenge is that these successful doctors who can assist in the remission via dietary and lifestyle changer, are usually are very expensive and don’t take insurance. Luckily I found a conventionally trained doctor who has the additional training of functional medicine that accepts insurance. I applied the basic principles of impacting the gene expression via the environmental factors. You can read the books they publish. We took a paleo approach with the diet and a rare inflammatory disease, RA, and Hashimoto was put in remission within a year to two. Dr. Jason Fung is having great success with fasting as a patient protocol for type 2 diabetes and thousands are off their medications that they have been on for decades. I believe the variable length for fasting depends on how sick the person may be and the tolerance to the stress of fasting. You must reach autophagy and stem cell rejuvenation which probably means a minimum of maybe 2 but probably 3-5 days? I would see how the results evolve. If I don’t see benefits I would extend the fast or do it more frequently.

  52. I was just telling my husband that I can’t eat 7 days a week! I fast 36 hours a week, often kick off this regime with a 3-5 day fast. Summers are SO easy to do this as we’re warm seriously don’t need to eat.

    Prior to my reboot fasting regime, my stomach was churning at weird times of the day, my bowels were not moving properly. I knew a good old fast would reset and reboot and it certainly is cheaper than a doctor’s appointment for churning stomach acid! Yikes! What would they have prescribed???

    I have found with this regime and with prayer (Catholic here), I’m so much better off. The 36 hour fast sleep is amazing! I offer this fast as penance and pray and am healed of many aliments because of it. What a wonderful simple tool we have!

  53. Very nice and helpful blog and comments.
    I watched a video of Dr. Jockers interviewing dr. Ed Group about his experience with water fasting. In that video he mentions that in order to get real results through stem cell regeneration a water fast should be at least 6 days long.
    He also mentions a case of (if I remeber correctly. I am not fasting long enough yet to have brain and memory improvements☺) a 40 year old man who water fasted for 14 days and saw most of his vital organs return to the state in which they were when he was around 15 years old. That is amazing and very motivating. Although I don’t intend to do a 14 day fast it encouraged me to commit to a 6 day water fast in the course of 2020.

  54. Why reset the immune system?

    In old age Thymus is already going extinct. How would you train new T Cells of rebooted immune system?

  55. I just wanted to chime in here because I’m seeing 3-4 day fasts referred to as being long, when really you’re just getting started by that time. I’ve done two 7-day fasts and most recently a 10-day. I’m talking about water fasting and would highly recommend the coaching of Tallis Barker at Wonderful resource.

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