Nutritional Geometry

We all know that the less we eat, the longer we live, and that periods of fasting, long and short, can also trigger a longevity dividend. What about macronutrient proportionsprotein, carbohydrates, and fat? The argument for carb restriction is that it helps keep insulin signaling down, and slows the inevitable advance of metabolic syndrome. The argument for protein restriction is that animals on protein restricted diets have sometimes been found to live longer, independent of total calorie intake. The argument for fat restriction is that mice on a high-fat diet have shortened lifespans compared to either high-carb or high-protein. So, what macronutrient proportions are best for people, or does it matter at all? I have advocated the carb restriction diet in the past, but today I’m considering the evidence for protein restriction, and speculating on the possibility we might be able to do both.

Nutritional Geometry is a 9-year-old Australian approach to macronutrient proportions which has been honing its message more recently [ref, ref, ref]. The topic has provided fodder for research grants (and for bloggers) because it is rich with nuance and resists generalization.

If you are looking for bottom-line advice, I’d say:

  • High-fluid, high fiber content are consistent recommendationsno tradeoffs, no qualifications. Leafy greens rule!
  • Low-protein when you’re young, higher protein when you’re old
  • Vegetable protein is preferable to meat or dairy
  • If you’re game to try something new, a high-fat ketogenic diet may offer advantages.

But the subtleties are interesting and worth exploring, and (as always) the best diet for you is the one you can live with.

Last year, the Australian group published a study in which they fed mice on 25 different diets, differing in protein, fat, carbohydrate, and energy density. The main result from this study is that mice fed a low protein, high carb diet lived longest, though they ate more food—presumably because they sensed that they were not getting enough protein. At the lowest protein concentrations, their total protein was still low, even though they ate more food, and they lived longer, even though they ate more food. For mice, a low-protein chow led to more eating and a longer life. The trick worked for low protein, high carb diets but not for low protein, high fat diets. In this case, the mice ate so much more food that they became obese and their lifespans were shorter. The optimum diet for female mice had an 11:1 ratio of carbohydrate to protein, and for male mice, 13:1.

If we extrapolate to humans, the message would be that for people who prefer not to restrict their portions, a very low protein diet provides a path to a longer life. But this is a dubious extrapolation. The mice were given no choice of chow. (There were 25 different formulations, but only one available to each cage of mice.)  People, in contrast, have a dizzying choice of foods. I know the feeling of having had my fill of fruit, and though not feeling really hungry, craving protein nevertheless. Humans are not at all comparable to lab mice in this regard.

A balanced diet?

A balanced diet?

I wonder for how many people a diet restricted to foods that have carb:protein ~ 12 to 1 is realistic. Here is a list of foods with carb:protein ratios [from USDA web site]:

protein2carb-ratiosConclusion: To get the low protein diet of the mouse experiment, you’d probably have to be a fructarian.

I was surprised to see that the study reported no benefit from a high-fiber diet.

Reduction in calorie intake was achieved by diluting the food with nondigestible cellulose, which allows ad libitum feeding but restricts total energy intake when compensation for dilution by increasing food intake is incomplete. Mice fed experimental diets containing 50% nondigestible cellulose ate a greater bulk of food (3.6 vs 2.5 g/day) but ingested about 30% less total energy than mice provided with food containing higher energy content (30 vs 42 kJ/day). Therefore, these mice had a reduction in energy intake similar to those reported in nearly all other studies of calorie restriction in which access to food was restricted… When corrected for lean body mass, the hazard ratio for death was not influenced by calorie intake, except at the highest energy intakes, which were achieved only by low-protein, high-fat diets.

Fiber in the chow filled the mice up, causing them to eat less calories (though more bulk) than they would have otherwise. But did they live longer? Yes, they did, though you might not get it from the language used here. Lifespan was not increased by lower calories “when corrected for lean body mass”, but whem mice are on a lifelong low-calorie diet, they don’t grow as large, so their lean body mass is smaller. Correction “for lean body mass” is generally not the way data is reported in these experiments. So the result here is not necessarily inconsistent with the great body of experimental results that say lifelong caloric restriction leads to longer lifespan.

Most interesting is the last caveat: The problem with high fat diets is that mice overeat, become obese and have shortened lifespans. But with both high fiber and high fat, the mice tended not to overeat, and their lifespans were enhanced.

This may suggest a practical diet strategy for humans. Mice on a high-fat diet ate a lot more calories, and similarly some people find deep fried foods and milk shakes tempt them to eat too much. But for those with the willpower to interrupt a high-fat meal, they may find that they don’t get hungry for several hours afterward. This is because fat is slower to be digested than either protein or (especially) carb. High-carb meals lead to a fast rise in blood sugar, then an insulin spike that makes blood sugar plummet, triggering hunger. After a high-fat meal, hunger is much slower to return.

High-fat meals lead mice to obesity and short lifespans because they overeat. Extra fiber in the food helps them to regulate their intake. If this works for humans, there is the possibility that a high-fat, high-fiber diet can offer the advantages of both protein restriction and low insulin. I’ll go into this option in depth next week.
Protein: How low can you go?

The biggest issue is maintaining muscle mass, which is crucial to vitality and wellbeing, and becomes a protective factor from mortality as we get older. We have all seen pictures of starving African children with bloated bellies. They are not actually suffering from insufficient calories, but insufficient protein. Their largest muscle, in the abdomen, has beeen deprived of protein so long it has lost all its tone.

Both Pederson and Rand (2013) recommend about 0.85g protein for each Kg of body weight. For a 160-pound man that’s 61g, and for a 125-pound woman, 47g of protein daily. Pederson found that all the diseases of old age are statistically associated with higher protein intake. More general sources quote a slightly lower 0.8g/Kg.

These numbers are only an average over many populations in many studies. Your body might need a lot more or a lot less protein than this, and your best indication is to monitor your energy level, your weight, your muscle mass, and blood analysis as you experiment with different diets.

In this study [2007] of Swedish women 30-49, those in the highest decile of protein consumption died at a rate 20% higher than those with the lowest decile. But mortality rates are low through that age range, and what is more important is the effect on health and mortality in the long term.


Animal vs vegetable protein

In a literature review, Pederson (2013) found links between animal protein intake and various mortality factors, but vegetable protein was either beneficial or neutral. Surprisingly, it is the high-protein diets that are associated with type-2 diabetes, not the high-carb diets. But this conclusion seems limited to animal sources.

This study [2012] from Harvard School of Public Health found a 13% increase in mortality for every daily meal at which red meat was consumed, rising to 20% for processed meats, corresponding to 2 to 3 years of extra life.

Seventh Day Adventists are, as a group, health- and diet-conscious, and they live longer. Their religion tells them not to eat meat, but many do anyway. Seventh Day Adventists who are vegetarian live 3 years longer than Seventh Day Adventists who eat meat.

How does the body know animal from vegetable protein? I have seen no theories on this. Animal protein is generally higher in methionine, but methionine restriction only lowers mortality when methionine intake is very low–probably not the case generally in any of these studies. It could be the saturated fat that accompanies the protein; or it could be hormones that are present in all animals, with higher levels in commercial meat; or it could be an effect mediated through the effect on intestinal flora. But my best guess is that it has to do with heightened inflammation from a low-level immune response to chronic exposure to alien animal proteins.


More protein as you get older

My favorite authority on this and other questions of diet is Valter Longo and his group at University of Southern California. In their 2014 review, they found a dividing line at age 65. Younger than 65, higher protein intake was associated with higher mortality, and older than 65, higher protein intake was associated with lower mortality. As in other studies, the damage was only visible for animal protein, and disappeared into the noise for vegetable protein.

Frailty is an issue in older adults., and greater muscle mass can support a more vigorous exercise regimen. This is a plausible reason for the increased protein need with advanced age. Longo also talks about IGF-1 signaling. IGF stands for “insulin-like growth factor”, and it is a hormone we need when we are young, but which increases mortality when we are older. Lower protein is associated with lower IGF-1, though the statistical association falls short of suggesting that this is the reason that low protein is beneficial.

This is the best article I have found on the subject of increasing protein need with age, but still it is not really what I’d like to see. Mortality in young people is not the best measure of whether a low protein diet is beneficial, because mortality in young people is still low, and even a temporary doubling of mortality make little difference. What we really want to know is how protein in the diet of young people affects their life expectancy when they get older. This is a study that has not yet been done, probably because it involves following a large population for a long period of time (like the Framingham Heart Study and the Whitehall Study in Britain, but these did not address protein.)
Roughage = Dietary Fiber

Everyone agrees that fiber in the diet has a large benefit for gut health and especially for preventing colorectal cancer. I have speculated that the benefit goes beyond this. A high-fiber diet is a calorie restriction program in itself. Fill your belly with fiber, and it you feel full with fewer calories. An ultra-high fiber diet pushes food through your digestive tract faster, so you absorb less of it. Fat is adsorbed on the fiber, and less of it makes it into your metabolism. High fiber in the gut encourages a microbial ecology that affords you less calories.

I speculate based on personal experience, but there is also some literature touching on the subject [ref, ref, ref]. “There was a considerable variability in digestibility of fiber components between individuals.”

Does fiber prevent the absorption of vitamins and other micronutrients as well? Maybe. I haven’t seen literature on the topic, but it makes sense that cellulose adsorbs a variety of molecules that are carried through the intestine undigested. Best to take your supplements separate from your fiber.

I am out on a limb recommending an ultra-high-fiber diet, and I suspect that results will vary widely among individuals. But what is not controversial is the health value of leafy green vegetables—the more the merrier.

Conclusions so far:

This much is clear: Green vegetables are good.  Animal protein is bad.

Beyond that, we might be tempted to interpret the Nutritional Geometry literature to say that “carbs are ok”.  I am wary of this conclusion, however.  It’s not just the standard warning that “mice are not people”. The benefits of a high-carb diet have only been shown in the context of severe protein restriction that I think is unrealistic for most of us. To be continued…

Next week: Metabolic Syndrome, Glycemic Load and The ketogenic Diet

26 thoughts on “Nutritional Geometry

  1. Your assumption that increased carbohydrate will push you towards metabolic syndrome is contradicted by experiments like Kempner’s rice diet where low fat, low protein, high carbohydrate (rice, fruit, sugar) produced a remarkable reversal of many of the symptoms of metabolic syndrome. Also, the diet of “high-number-of-centenarian” groups around the world (okinawans, sardinians, the blue zone groups) are reported to be low fat, low protein, high carbohydrate similar to Dr. Dean Ornish’s heart healthy diet and Dr. McDougall’s recommenations (eat mostly potatoes). Once the fat calories drop to 10% or less, high carbohydrate does not appear to be a risk factor and this very low fat diet seems to be what long lived populations of humans (not mice) are eating.

      • It was 1984 when I said goodbye to a doctor who wanted to keep me having antiinflammatories for the rest of my life. I have practiced so-called healthy lifestyles one after another since. Long jump and 2016 looks better than ever to talk about health for what it is. We must get as many voices out of the wilderness and place them into a structured health science that will produce a qualified health professional able to help the individual in the street. Why is it that health science has not yet been allowed to sprout? What is going on with academia and its universities, governments with their politicians and the financial system with its investors?

        This is a 79-year-old mouse who enjoys every second of its existence without medications or supplements of any sort. All right, back to first person. However, I have gone through a lot of trial and error to get here. Valter Longo, yes, a young Italian who got a perfect niche for himself by reinventing the fasting wheel, while aware of the boundaries established by the medical industry. Fasting starves cancer, he says, but it is worth nothing without chemotherapy… He surely knows that well supervised fasting could be enough, but is clever enough to stop before being knocked off the rails. He has invented a fast-mimicking diet, to minimize the panic of a possible hunger death. Luigi Fontana’s favourite proteins are also the vegetable type.

        The 65 years of age turning point in the survey report was an eye-opener for me and I certainly took advantage of it. In 2005 I wrote in my diary about the advanced-age state of my joints. How wrong I was! When I adopted Time Restricted Feeding (TRF) in 2013 my weight went down along with the BMI, which shifted from the overweight side of the scale to a comfortable 23, and it kept that way. However, not all was as impressive as my loss of weight. My wrists, knees, shoulders, neck and at times muscles, were the object of eight pain entries to my diary during the first seven months of 2014.

        Recovery times improved noticeably, I must say. I had kept a very conservative attitude towards eating proteins for many years, to the point of having a proteinic meal only once a week. As soon as I read the study results mentioned above, I realised that because I was well past age 65, probably missed very valuable nutrients. My first meal remained a 5-fruit and nuts brunch, but to the second I added a daily animal protein food, such as fish, eggs or meat. Eureka! My joint problems disappeared in a seemingly magic way. Appetite and weight have somewhat increased, but my levels of energy have remained unhindered for two years. Although I always remain vigilant to any bodily messages, nothing suggested so far that I should change.

        Aging must be considered as a byproduct of health, though the extension of lifespan in general is misleading, considering the unproductive and suffering state of many survivors of my age that I constantly see around. My slight weight increase is of no concern. A 10-year study of over 9,000 people by Leon Flicker et al., from the University of Western Australia revealed a BMI of 26.6 kg/ m2 in men and 26.26 kg/ m2 in women led to the lowest risk of death. And I am well below that, though over the age of those who participated.

          • Dear Haim.

            Thanks for your comments.
            My success with respect to the joints continues unabated, such as I described in the article.
            I only referred to the most important aspect, but there are other facets and/or details that may also deserve attention.
            I will surely elaborate and would appreciate if you point to something you may have in mind that could get the ball rolling.
            Please let us know what branch of science you have been involved with.


  2. If a food is 50% cellulose it is a high fiber food – so you can’t logically separate the dilution of nutrients from the high fiber content of the diluent as the cause of the under-caloried, cellulose-fed, mice’s longevity, I think.
    Also, mice don’t get colon cancer – when they get cancers it’s usually sarcomas (unlike humans).

  3. There was no mention in your article about the composition of the high fat diets. Were the mice fed unsaturated or saturated fats? There seems to be evidence that saturated fat is actually better likely due to the greater oxidation potential in unsaturated oils.

    • Yes! Thank you for pointing this out, Joyce. The kind of fat in the diet could easily make more difference than the amount.

  4. Low protein diets make perfect sense when you consider mTor. MTor is one of the cellular protein sensors that is shut down by Rapamycin. Which is as we all know, the best proven pharmaceutical life extension agent. How can we shut down mTor naturally? – just eat less protein, but it has to be around 10%. If its much higher, like in lacto-ovo vegetarians, it is not low enough to shut down mTor. That’s why many vegetarian studies show little benefit. Methionine restriction is also proven for longevity in all tested organisms. Plant foods are significantly lower in methionine than animal proteins with a few notable exceptions like brazil nuts. The simple, easy way to cut your protein to 11-12% AND cut methionine simultaneously is to eat vegan. And eating an incomplete vegetable protein is equivalent to lowering protein a few more percent to around 10%. I have an app that calculates protein, and even when eating a well rounded natural vegan diet, it is nearly impossible to get below 10%. Studies have shown that low protein diets at around 10% do not cause the deficiencies that you mention which occur around 5-6%. Lifting weights while on a low protein diet conserves muscle strength, and in fact you can continue to increase strength but you will get thinner at first and forget bulking up. Eating a high fruit diet will cause even a lower protein levels but will also cause more insulin spikes from fructose and higher levels of AGEs, and therefor, I believe are detrimental as they get more extreme. Acarbose is a high carb diet’s best friend. It has been shown to increase lifespan and healthspan in multiple organisms including humans. If you take only 12.5 -25 mg with a carb meal it shaves the top of the insuling/sugar spike without any gas or digestive upset. Take more than that and its even better, but you might not want to be in public. The other benefit is it increases FGF21 production in the intestines. A natural whole food vegan diet is NOT ideal however. There are several problems including, sticky platelets causing increased risk of stroke. Also B12, and vitamin D are usually low in vegans. That is why many studies only show moderate health improvements with eating vegan since many vegans in the studies believe in going completely natural which means they are seriously deficient in B12, D, and DHA. With the wonders of modern science we can make it an ideal longevity diet by eating a well rounded vegan diet, taking B vitamins, Vitamin D, fish oil, and eating some ground flax daily, in combination with small doses of acarbose when eating fruit or high carb meals. I believe this diet plus some other phyto-nutrient supplements will dramatically reduce the odds of the four western diseases of excess: Cancer, Heart Disease, Diabetes and Alzheimers, and cut the risk of stroke. – 2 cents 🙂

  5. Thanks for this very helpful information. I am very curious to learn more about taking supplements “separate from your fiber”. I’m wondering how much time is sufficient. I have recently started a daily regime where I take a mixture of 1 tbsp psyllium husk and 1 tbsp inulin fiber mixed in water twice a day and the morning, when I take my fish oil (actually krill oil) and vitamin D supplements, is one of the most convenient times to try to chug down the not exactly tasty mixture. But now I’m thinking I should rethink the schedule and I’m wondering, if I wait an hour, is that enough separation? Thanks again for all this great information.

    • Regarding fiber, wouldn’t it be better to get your fiber from the natural source via a veggie smoothie? Repackaged nutrients would miss out on the nutrients/elements that science has yet to capture/define/label and repackage in man-made supplements. As much progress as we have made in science, the missing ingredients of “essentials” are already packaged in the produce we can easily blend and consume.

  6. Your thoughts

    To illustrate the power of the approach, Professor Raubenheimer and Professor Simpson plotted data for the composition of 116 diets, compiled from previous published studies examining macronutrient ratios (carbohydrate, fats and protein) and energy intake in humans.

    Their model shows that protein was the strongest driver influencing diet, regulating the intake of fat and carbohydrate. This finding is consistent with the previously observed ‘protein leverage’ phenomenon, in which the strong human appetite for protein leverages the intake of fats, carbohydrates and total energy.
    Nutritional Ecology and Human Health

  7. Josh, I think you’re absolutely correct in assuming that if one can watch how much fat they eat, it is probably going to be of benefit to humans to eat a bit more than 10% fat. Especially when it is a fat like EVOO. We don’t want carbs potentiating insulin too much at super high levels. Also, although I know she had bulletproof genetics, jeanne calment is probably the best example of not being overweight and eating a lot of monounsaturated fat and living a long time. I wanna eat like her!

  8. Are sand, sawdust, fruit pectin, leafy vegetables, indigestible fractions of meat, etc. equivalent in their health benefits as “fiber”? Clearly not. Each probably has pluses and minuses. I’m ready to bet that a mixture fruit, nut and vegetable sources will be the optimum, but what mix, when, and how much?. It would be great to see you expand on this facet of nutrition.

  9. Dear Josh, what is your view on tofu and tempeh, are they good after all despite the estrogen? Does the estrogen have an insignificant effect on us?

    • I am confident that moderate intake of soy products is fine. I personally eat more than “moderate” amounts, and it seems fine for me, but maybe it’s not right for everyone. I have heard that tempeh avoids the problem of phytoestrogens in tofu and other soy products.

      • Is it more the refinement/processed tofu/soy products that create / bring up such problems mentioned of estrogen, and related issues??

        How is it that a billion ++ asians on tofu beyond “moderate amounts” for 100’s++ years have not had issues? Or is it that they have, but were never labeled/noticed by science??

        Curious as well regarding intake of rice and noodles that have been quite popular in the asian culture.

        Maybe it’s genetics? Of course, I don’t have any data off hand to spout life expectancy of “asians” (pick a group) compared to our western counterparts. Genetics or environmental? and yes, it’s my assumption asians historically have lived longer than westerners (americans), but this is all opinion/assumption.

        Thanks for an awesome blog/content!

  10. Acording to some studies Glycine compensates the effects of Methionine, and even promotes longevity. Indeed it’s one of the themes of Ray Peat. It that’s true then the main issue would be the composition of protein, as animal v.s. vegetal, rather the total ingest. Maybe a high ingest of protein in the form of gelatin can enahance longevity, even if the total protein intake is high.


  11. Regarding the seeming ill effects of animal, but not plant, protein on longevity, I have an idea. What if the culprit is not animal protein at all? Perhaps animal protein is just a proxy for something else? I would propose that it’s more likely that excess iron is the culprit. There’s a good body of evidence that suggests that iron accumulation is a big driver behind the major diseases of aging. See here ( and here ( for some more information about this.

    Animal protein might just be a correlate for higher iron levels. Meat is, of course, the largest source of iron in most people’s diets. And the much-vilified red meat has more iron than other kinds of meat.

    As to why animal protein seems detrimental when younger, but beneficial when older, perhaps when one gets older, getting enough protein to maintain muscle mass (which is best done with animal protein, rather than plant-based) becomes more important than having low iron in the body. That’s just speculation, though. Josh, I’d love to hear your thoughts.

    • Joshua –
      Yes, animal protein is associated with higher iron intake, and it’s hard to separate the two effects. Animal protein also tends to come with animal fats and with hormones, both naturally-occurring and those associated with modern factory farming. I don’t know of any study that has convincingly separated these out to document an independent mortality cost associated with animal protein alone.
      – Josh

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