The advantage of a low-carb diet is that it minimizes insulin spikes that can contribute to loss of insulin sensitivity=metabolic syndrome. The advantage of a low-protein diet is that it offers some of the anti-aging benefits of calorie restriction, and is associated with lower all-cause mortality. Can the two be combined? The low-protein, low-carb diet is by definition a high-fat diet. High fat diets are terrible for mice, but maybe they’re good for people. For more than a century, many people have found a high-fat diet is a path toward weight loss. Just in the last few years, there is a lot of salesmanship based on a little science that suggests a ketogenic diet can be healthy for the brain.
Does a high-fat diet induce ketosis? Is it practical? Is there a price to pay for too much oil?
This blog edition also features a description of my personal eating habits, as a curious example rather than a universal prescription.
There are but three macronutrient classes, so the only way to have a low-protein, low-carb diet is to eat a lot of fats. The low-carb diet has at least a 150-year history.
One of the first registries on low-carbohydrate diets was in 1860 when English casket maker William Banting was prompted to lose weight and decided to write “Letter on Corpulence, Addressed to the Public”, which aimed to completely avoid starch and sugar. Banting lost 45 pounds in a few weeks (with additional weight loss over several months) on a diet composed by meat (generally mutton or beef – plus poultry and fish), two very small (1 ounce) portions a day of rusk or dry toast, tea (with no sugar or milk), and a 2-4 drinks of dry wine or port a day as spelled out in his own writings. Thus, the Banting diet became a very well known method during that period of the 19th century, promoted also for weight loss and diabetes control [Wikipedia].
Diets comprising 80-90% fat have a remarkable benefit for people who suffer epileptic seizures. Known generically as ketogenic diets, they have been recommended by extension for other neurological disorders, and, of course, for diabetes (types 1 and 2). There is some evidence that low-carb diets protect against Alzheimer’s Disease. When sugar is not available, the body turns to fat as a fuel, and converts fat to three related biochemical forms (called ketone bodies) as a circulating intermediary. Cancer cells, however, can’t use ketones, so cancer also responds to a ketogenic diet (and even better to fasting). But if you don’t have a life-threatening disease and you don’t happen to be an Inuit, a diet that is 80% fat may feel extreme. It takes a lot of motivation to stick to a ketogenic diet, and for people who are basically well, the promised benefits are not commensurate with the discipline. All of the evidence for benefit in healthy individuals is theoretical, based on biochemistry.
Studies of lab mice consistently show that a high fat diet leads to shorter life span, compared to carb- or protein-based diets. The reason for this seems to be that fat nurtures a kind of intestinal flora that excite an immune response called endotoxicity. It’s the elevated inflammation that shortens lifespan. Whether this response is essential to high-fat diets or whether it is exacerbated by refined carbohydrates in the mouse chow, whether endotoxicity is also induced in humans on a high-fat diet–all these subjects are vigorously debated. The one clear message is that fiber is an antidote, so that anyone considering a high-fat diet should be doubling up on dietary fiber.
A Tasty, Satisfying Fat-based Vegan Diet
Think avocado salads and fried green vegetables with a bit of tofu. Think coconut and walnuts and greens and more greens. Here are some recipes from the incomparable Enid Kassner. All are guaranteed delicious, and all have 70-75% of calories from fat, with the residual comprising various mixtures of carb and protein.
1. Saag Tofu
8 oz spinach (washed and roughly chopped)
5 oz fresh tomato, chopped
6 oz extra firm tofu
1.5 oz coconut oil (3T)
Grated fresh ginger, chopped garlic, garam masala
(Indian spice mixture)
Press extra liquid from tofu using a towel. Cut into cubes, sprinkle with salt, and microwave about 3-4 minutes. Set aside. Heat oil and add ginger, garlic, and spinach. Stir frequently as spinach cooks and reduces in volume. Add chopped tomato and cook lightly, adding tofu, salt and garam masala to taste.
2. Fried Cauliflower with Tofu and Cashews
9 oz cauliflower florets
2.5 oz sweet red pepper, sliced
2T + 1t peanut oil
Scant oz chopped roasted cashews
4 oz extra firm tofu
Press extra liquid from tofu using a towel. Cut into cubes, sprinkle with salt, and microwave about 3-4 minutes. Set aside.
Heat oil and cook vegetables, stirring frequently, adding garlilc, if desired. Add tofu and nuts, salting to taste.
3. Marinated Vegetables
5.5 oz mushrooms, cleaned and sliced
3 oz chopped cucumber
4 oz green beans, chopped and lightly boiled (about 3-4 minutes)
.5 oz finely chopped sweet onion
2 oz sliced black olives
1.25 oz toasted almonds, sliced or chopped
1.5 oz olive oil (3T)
1 oz vinegar (2T)
Combine olives and vegetables and marinate in oil and vinegar, adding salt and pepper to taste. Can also add dried herbs, such as oregano, basil, or thyme. Let sit several hours at room temperature or overnight in refrigerator. Sprinkle with nuts when ready to eat.
A Bit of Biochem
Ketones are carbon chain molecules with an oxygen double-bonded to a carbon (C=O) somewhere in the middle. Beta hydroxybutyrate (BHB) is best-known of three “ketone bodies” that circulate in the blood. It is burned as fuel, but it is also a signal molecule “BHB has been found to act as a histone deacetylase (HDAC) inhibitor and to increase brain-derived neurotrophic factor (BNDF) levels and TrkB signaling in the hippocampus.” [ref] (BHB signals growth of new neurons and affects gene expression in unknown, complex but probably good ways, since BHB is associated with fasting and exercise.)
When the body burns ketones instead of glucose, less oxygen is needed. Theoretically, in intense aerobic exercise, when the body is limited by how fast oxygen can be pumped through the lungs and into the blood, there ought to be a slight benefit in power when the body is in ketosis mode. One wonky self-experimenter working with the lab of Dominic D’Agostino at U of S Florida claims to have measured and confirmed this effect in himself.
If much of the benefit of a low-carb diet comes from the body’s adaptation via ketosis, why not cut out the middleman and just eat ketones? Once again, the miracle of capitalism has advanced ahead of the plodding pace of epidemiological science. There are several products to choose from. Raspberry ketones seem to be worthless. Ketones are cheap to manufacture, but you need a large quantity because it’s a food, not a supplement, and ketones taste awful. (Why should sugar taste so good when it’s so bad for us, and why should ketones taste so bad? Maybe because evolution is keenly concerned with our short-term survival, but is ambivalent about prolonging our lives.) Medium-chain triglycerides as found in coconut oil and butter seem to be a platable way to boost the benefits of a ketogenic diet, including weigh loss.
D’Agostino is researching and developing palatable ketone supplements.
This summer, Andrew Murray and colleagues at Oxford University reported an experiment in which mice had a ketone supplement (not BHB) added to their chow, and they showed both faster learning and greater aerobic capacity [pre-pub ref].
Modified Atkins Diet
Dom D’Agostino is the king of ketogenic research, and for himself he has chosen a Modified Atkins Diet accompanied by ketogenic substitutes, which offers much of the same benefit as a ketogenic diet. The original Atkins diet was heavy on meat and fish. The Modified Atkins Diet developed at Johns Hopkins for epilepsy has less protein, 65% fat and ultra-low carbohydrates (~5%) but more flexible than the ketogenic diet.
There are a range of generic Atkins diet spinoffs, including some that have less or zero meat. (I keep coming back to vegetarian options not just because my inclination is in this direction, but because there is good evidence for a longevity benefit. I also respect that other bodies make other choices.) All the “modified” versions introduce a lot more green vegetables, because their fiber and nutrients add a lot of value, and because the diet is much more varied and platable with vegetables. Some Atkins versions allow limited fruit. Atkins-spinoff diets tends to have less protein than the original and 50-60% fat, with limited carbohydrates, but more than the strict 5% prescribed for epilepsy by the Hopkins docs.
People ask how I eat, and I’m happy to tell them, but I make clear this is not a recommendation. Diets are personalized. At one level, there’s what you can live with and feels good to you; at a deeper level, you can experiment with different diets, see how your weight and your energy level and your emotional and intellectual life respond; at a deeper level yet, sensitize yourself to your body’s signals with yoga or biofeedback or meditation techniques, and perhaps your body will let you know what it wants.
Fresh vegetables, fruits, nuts, soy and other beans are the mainstay of what I live on. In addition to fat from nuts, I dress salads generously and stir-fry my vegetables in oil. I have been vegetarian since 1973. Lately, my diet is close to vegan, ultra-high fiber, low carb, relatively high in protein. (No vegetarian diet can be high-protein by Atkins standards.) Fish oil capsules are my one departure from strict vegetarianism. I start the day with a big bowl of raw wheat bran (the only wheat that I eat), made palatable with fruit and soymilk, sometimes blended in a smoothie.
(I’m 67 and exercise frequently and in diverse ways. If I were younger or less active, I would eat less protein.)
I eat no grains or potatoes: no rice, wheat, pastries, pasta, or cereals. Other starches occasionally: carrots, winter squash, beets, parsnips. I eat fruit liberally. I will also occasionally savor a square of chocolate or a spoonful of ice cream as a special treat. I’ll stop what I’m doing and roll it around in my mouth, extending and savoring the experience. An absolute proscription of grains helps me say no to cookies and cakes.
I confine eating to 12 hours each day. I fast one day a week, about 32 hours from Wed evening to Friday morning. I do longer fasts 2 or 3 times a year, and Longo semi-fasts another 4 or 5 times a year.
While I’m in personal mode, I’ll add a note on flatulence. What about all that fiber and beans? The truth is that I’ve had a gassy metabolism my entire life, especially so when I was growing up on a typical American diet of meat-and-potatoes, milk and cookies. In the last 10 years, my body has made a transition to a less prodigious level of flatulence, and I don’t know why–but this has been despite the beans and the wheat bran. (I still can’t eat black turtle beans, though I’d like to.)
The Bototm Line (concluding three long blogs on nutrition)
If we are what we eat, maybe the surprising thing is that what we eat makes so little difference that it requires human studies with tens of thousands of participants to be able to detect an effect of diet on lifespan. Monarch caterpillars eat only milkweed. Pandas won’t eat anything but bamboo. There are hundreds of species of wasp, each co-evolved to drink nectar from only a single species of fig flower. But we humans are omnivores, and our bodies are geniuses of homeostasis, able to stay pretty well on track no matter what we put into them. The differences in epidemiological studies amount to a few percent of lifespan, even as test diets are varied all over the map. Native Americans of the Paiute tribe eat grasshoppers, and Inuits eat blubber; on the Trobriand Islands they eat yams, Amazon tribes eat fruit, while the Masai eat a mixture of ox blood and milk. Yet the similarities in their life trajectories overwhelm the differences.