Cryonics, Health, Science

The Cryo-Paleo Solution

Originally published as a Cryonics magazine web exclusive

Cryonics is an odd service. When you pay for a service—whether it’s having your car cleaned, your taxes prepared, or your dinner served—you typically want what you’ve paid for as soon as possible. Cryopreservation is unusual in that those who pay for it hope never to need it. If we do need it, we hope it will be later rather than sooner. (Of course it’s not unique in this; companies retain lawyers who they hope not to need.)

Those of us with arrangements for cryopreservation have a well-worn but deeply wise aphorism: “Cryonics is the second worst thing that can happen to you.” Both the uncertainty of the cryonics endeavor and the fact that we want to remain in direct control of our fate means that we should attempt to put off the need for cryopreservation for as long as possible. Extending maximum life span is tough. Calorie restriction might do it, although Aubrey de Grey and Michael Rose have argued that the effect in humans is likely to be modest.

We have many more options for reducing our chances of dying early—and for enjoying improved health, vigor, and well-being in the meantime. The subject of this article is a currently unfashionable option with a potentially huge health payoff. This is the paleo diet, also known as the caveman diet, the new evolution diet, and the primal diet. The plan is actually more than simply diet. It includes a perspective on exercise and other aspects of healthy living. The topic is complex. My aim here is merely to introduce and hopefully intrigue you to investigate further.

I’ll sketch out what the paleo diet is, its rationale, highlight some of the crucial ways in which it differs from standard dietary advice, and consider how a backward-looking paleo perspective fits with the forward-thinking typical for cryonicists, how it benefits health, how intermittent fasting can add to the benefits, and what a paleo approach to exercise looks like.

What is the paleo diet?

Answering this question is complicated by disagreements among its advocates and by the range of foods eaten by our Paleolithic ancestors. The basic idea is that the paleo diet is the only diet that ideally fits our genetic makeup. Our genes and the functions they regulate change very slowly, over many generations. The human genetic endowment was formed over millions of years of evolution. The genus homo is almost two and half million years old, and includes humans and species closely related to us. The Paleolithic era (or, more informally, the Stone Age) accounts for 99.5% of that human history.

During that time, our ancestors lived as hunters and gatherers. This changed dramatically with the advent of agriculture, a mere five to ten thousand years (really little more than two thousand years in most of Europe). We lived as hunter-gatherers for over a hundred thousand generations, compared to six hundred generations as farmers and ten generations living in the industrial age. Our genes have been almost entirely shaped by the conditions of the Paleolithic era.

Hunter-gatherers (HGs) consumed large amounts of animal food, some getting 100% of calories from meat or fish. The HG diet was higher in protein compared to today and higher in fat. Crucially, it was much lower in carbohydrates. Carbohydrates that were eaten generally had a low glycemic load. Even the fruits then were less sweet than today’s, because we have bred for sweetness over centuries. Refined, high-carbohydrate foods have been eaten only for the last few hundred years—just for the last thousandth of one percent of our 2.5 million years as humans. We did not evolve to eat easily digestible starches, refined carbohydrates (such as flour and white rice), and sugars. Paleo advocates also prefer to eat grass-fed beef and free range chickens because of their superior fatty acid profile (a higher omega-3 to omega-6 ratio) as compared to factory-farmed, grain-fed animals.

Probably the leading paleo advocate (and perhaps the most scientifically grounded) is Loren Cordain. In his book, The Paleo Diet, he condenses the paleo approach to food into six ground rules: All the lean meats, fish, and seafood you can eat. All the fruits and nonstarchy vegetables you can eat. No cereals. No legumes. No dairy products.  No processed foods. (Other paleo writers dispute the need for meat to be lean.)

Expanding on that highly compressed outline, Cordain also offers Seven Keys of the Paleo Diet: 1. Eat a relatively high amount of animal protein compared to the typical American diet. 2. Eat fewer carbohydrates, but lots of good carbohydrates—from fruits and vegetables, not from grains, starchy tubers, and refined sugars. 3. Eat large amounts of fiber from nonstarchy fruits and vegetables. 4. Eat a moderate amount of fat, with more monounsaturated and polyunsaturated fats than saturated fats and nearly equal amounts of omega 3 and omega 6 fats. 5. Eat foods with a high potassium content and a low sodium content. 6. Eat a diet with a net alkaline load. 7. Eat foods rich in plant phytochemicals, vitamins, minerals, and antioxidants.

Other versions of the paleo diet look more similar to the Atkins diet. But even these more fat-friendly versions differ from Atkins in that the latter allows any amount of processed meat, and can be more restrictive of vegetables and fruit (especially in the early stages of weight loss). Although the Zone diet shares some recommendations with paleo, the Zone is too high in carbs, too fat-phobic, too structured, and wrongly recommends soy.

Paleo Variations

Sometimes I prefer to talk of a “NeoPaleo” diet, to emphasize the point (often misunderstood) that we are not trying to exactly emulate a unique Paleolithic diet while rejecting all modern innovations in nutrition. Critics who point out that there was no single, universal diet over those 2.5 million years are right, of course. But I don’t know of any paleo advocate who argues otherwise. Clearly, ancestral diets varied significantly at different times and in different environments. A major difference exists between the Ice Age Paleolithic and post-Ice Age. Sometimes we were more hunters than gatherers; at other times the opposite. Sometimes (actually quite a lot of the time) Paleolithic people ate practically no fruits or vegetables, but in temperate times non-starchy fruits and vegetables became a larger part of the diet.

Anyone wanting to be a paleo purist will also run into the problem of disagreements among advocates. The good side to this is that it encourages you to examine the evidence for yourself rather than blindly following a unitary regimen. Some of the differences—such as whether any amount of salt should be used—are relatively trivial. We can find a more substantial divergence on the issue of the optimal level of carbohydrates, and on the related matter of whether glycemic index or glycemic load is important. While all paleo writers agree on throwing out starches, legumes, and grains, and refined sugars, that leaves fruits (and to a lesser extent vegetables and nuts) as a source of carbs. Is any amount of fruit good or not?

Cordain recommends a relatively high 22% to 40% of calories from carbohydrates. For a 2,000 calorie diet, that would amount to 440 to 800g. Mark Sisson, author of The Primal Blueprint, specifies  100 to 150g as the “Primal Maintenance Zone”, while 50 to 100g is the “Primal Sweet Spot for Effortless Weight Loss”. The paleo-compatible analysis by Gary Taubes, author of Why We Get Fat and Good Calories, Bad Calories, recommends 20g or less. Nora Gedgaudas, author of Primal Body, Primal Mind, agrees with Taubes’ view that there is no human dietary requirement for carbohydrates.

Views also diverge on the issue of the optimal amount or range of saturated fat. Cordain favors lean meat, whereas Sisson, Gedgaudas, and Taubes argue that higher levels of saturated fat are fine. Sisson allows modest amounts of dairy but most others rule out dairy other than eggs. Cordain used to be an exception in recommending canola oil, but no longer does. One point that probably all the authors would agree on to some degree is that the optimal amount of dairy and saturated fat will vary across individuals. Some can tolerate dairy better than others, and genetic differences (such as possessing the apolipoprotein E3 variant) may mean some people do well with a lower intake of saturated fat.

Among the other differences of opinion, Cordain and Taubes seem unconcerned about diet sodas and artificial sweeteners, whereas Sisson is less accommodating (without entirely ruling them out). Everyone agrees that being vegetarian and paleo is difficult and not a good idea from an optimal health standpoint but some take a harder line on the compatibility of the two. They would all agree it’s better to be a paleo-vegetarian than just a vegetarian.


Looking for health guidance by looking back, say, 40,000 years, may seem odd coming from a cryonicist, transhumanist, and someone known for thinking about the future. That impression might be reinforced by reading paleo proponent Mark Sisson’s book or blog posts, since he often rails against genetically modified foods and almost any kind of modern changes to our food. If the construction were not so clumsy, I might call my position “Futurist-NeoPaleo”. That would emphasize the point that old is not necessarily optimal, that modern doesn’t mean bad, and that paleo is an approximation that forms a good starting point but not the whole truth.

Grains may be bad for us (see below) but what if we could genetically modify our foods (or ourselves) to use them without any downsides? That may even be essential if we are to feed the global population in good health. Personally, I would be delighted if I were able to stop eating animals and instead eat animal nutrients grown in a vat. Only someone dogmatically committed to an absolute, a priori paleo position (one not entirely tied to the conditions of health) would reject these possibilities out of hand. At the same time, it’s crucial to acknowledge that until we can reengineer ourselves or have reengineered grains to work better with our biology, we should take into account the diet for which we are adapted.

Some modern additions to diet and health, while not available to Paleolithic people make excellent sense given the different conditions in which we live. (And due to our living, on average, much longer since we are far less susceptible to deadly infections and accidents.) It’s sensible to wear sunglasses, since we live a lot longer than paleo people and can accumulate more eye damage. It also makes sense to get flu shots, even though these were unavailable throughout almost all of our history.

It probably also makes sense to take some nutritional supplements. While Paleolithic people in many regions were regularly exposed to hours of sunlight, our modern life style keeps most of us out of the sun, perhaps indicating a need to supplement our diets with vitamin D. I don’t see any sensible paleo objection to taking a general vitamin supplement, and perhaps additional fish oil and probiotics.

Paleo is an excellent starting point. But we can’t be sure that it is optimal for health. We must remain open to direct evidence. For instance, the evolutionary argument behind paleo eating would suggest that we should consume no more than a very few grams of salt per day. But the body, being a complex system, might never have become optimized to that level. It’s possible that a higher intake is better. Paleolithic people may have eaten a lot of food raw, but that doesn’t mean it’s not better to cook moderately at least some kinds of meat.

Health benefits of going paleo

For thirty years I was a believer in the standard wisdom that a healthy diet is one low in fat and high in carbohydrates primarily from high-fiber sources. The shift to paleo (which took place last year) is therefore a major change of mind. If you hold the views I did (and hadn’t looked into the subject for many years), you may be skeptical, and you certainly won’t find the detailed evidence to change your mind in this article. I’m going to make naked assertions about the health of going paleo, leaving you to take a look at the sources provided at the end for the details.

The advent of agriculture was followed by a decline in human stature, bone density, strength, dental development, and health. There was an increase in birth defects, malnutrition, and degenerative diseases. Evolutionary biologist Jared Diamond has gone so far as to declare agriculture and the advent of grains as the “worst mistake in the history of the human race”. Despite improvements in medicine, numerous health problems have greatly expanded over the last century as we replaced animal fats with vegetable oils, trans fats, and carbohydrates (especially refined carbs including high fructose corn syrup).

Low-fat diets encourage us to load up on grain products (wheat, rice, bread, pasta, cereal, corn). Unfortunately, consumption of grains yields relatively poor nutrition but provokes a high insulin response. Grains (and legumes) also contain problematic anti-nutrients such as phytates, lectins, gluten, and goitrogens (thyroid-inhibiting substances). Lectins are natural plant toxins that can inhibit healthy gastrointestinal function and provoke an autoimmune response.

Gluten is a large, water-soluble protein found in most grains, including wheat, barley, and rye. Perhaps one third of us are gluten-intolerant or gluten-sensitive. The rest of us may suffer negative consequences (such as disruption of healthy immune function and inflammation) that are less obvious. Those who are gluten-intolerant can develop conditions including dermatitis, joint pain, acid reflux, reproductive problems, autoimmune disorders, and celiac disease.

The phytic acid found in grains inhibits the absorption of minerals by binding them and eliminating them from the body. Heavy consumption can lead to deficiency of minerals including calcium, iron, magnesium, and zinc. Legumes also contain lectins as well as protease inhibitors, which can damage the pancreas and reduce the body’s ability to digest and use protein. It’s true that phytic acid and other anti-nutrients can be reduced or eliminated if you take the trouble to pre-soak, sprout, or ferment these foods, but are you going to do that often?

Going paleo means avoiding grains and legumes, thereby avoiding a major cause of numerous maladies, that are thought to include allergies, food sensitivities, auto-immune disorders, colon cancer, pancreatic disorders, mineral deficiencies, celiac disease, epilepsy, cerebellar ataxias, peripheral neuropathies of axonal or demyelinating type, and myopathologies, autism, and schizophrenia. Obviously we vary greatly in how we react to grains, but I don’t know of any tests that reliably tell you how well you handle grains. You might eat grains and thrive, but that doesn’t mean they aren’t doing you some harm nor that they aren’t a bad bet: some people smoke and live long, healthy lives, yet smoking remains a bad bet.

Eating paleo-style can help avoid or reduce many health problems. Again, it would take up far too much space to support these claims with the relevant evidence (which you will find in the source below). The evidence I’ve seen leads me to believe that eating paleo reduces your chances of insulin resistance, diabetes, obesity, celiac disease (and the combination metabolic syndrome), high blood pressure, cancer, many disorders linked to inflammation, including auto-immune disorders such as arthritis, and improves your blood lipids, reduces your hunger and raises your energy level.

It’s important to note that you can expect a transitional period of adaptation of a few weeks to a couple of months. Your body needs time to switch from primarily burning carbohydrates for fuel to burning fat, especially if you adopt the more carbohydrate-restricted forms of paleo (which I believe to be the healthiest). You might want to take supplemental magnesium, calcium, and zinc during the transition.

While the caution about a transition period is standard in the paleo literature, in my own case I experienced no dip in energy at any time, despite continuing intense workouts (both aerobic and muscular). Nor did I find the restrictions to amount to a significant sacrifice. The almost immediate loss of craving for carbohydrates surprised me. I’ve found the new types of food—especially the highly colorful salads that are now daily treats—to more than make up for the foods I’ve let go of.

Start now or later?

Another wrinkle was added to the paleo story for me last year when I listened to a talk by evolutionary biologist Michael Rose. Professor Rose is a strong proponent of the paleo diet, but only for people over the age of 35 or 40 (earlier if you’re not Eurasian). In his talk (to which you’ll find a link below), he argues that most of us have adapted well to an agricultural diet at earlier ages. But as we get older (a little past the usual age of reproduction) those adaptations begin to fail. I don’t think Rose would disagree that even young people might be healthier on a paleo diet, but he only strongly urges making the dietary switch after the first three to four decades of life.

Intermittent fasting

We’ve become used to eating three square meals per day (and Taco Bell is pushing a “fourthmeal”). Paleolithic man certainly didn’t eat this way; nor do animals in the wild. More likely, after a kill they would eat a lot then rest. They would become hungry and have to go out and hunt or gather more food. They would have been used to going without food for longer periods than we do today. Although not by design, they practiced intermittent fasting (IF). Abundant evidence exists to suggest that IF generates major health benefits, even when it doesn’t lead to a lower total calorie intake.

Intermittent fasting can be done in a variety of ways, although skipping only one meal is probably insufficient to reap significant benefits. One popular, low-level approach is to fast for sixteen hours, leaving yourself an eight-hour window for eating primally. Even better is to fast for a full twenty-four hours occasionally—as often as once or twice per week. This might sound difficult and painful, but it’s much easier to skip meals when your regular diet is relatively low-carb, leading to stable blood sugar and insulin levels. If IF sounds appealing as a health measure but you’re not yet eating paleo or low-carb, it’s probably best to wait for a few weeks until your body has adapted to use fat stores for energy rather than carbohydrates.

What are the likely health and longevity benefits of supercharging paleo with IF? While being considerably easier than permanent calorie restriction, it appears to have many of the same benefits. These include increased insulin sensitivity, stronger resistance to stress, improved cognitive clarity, improved blood lipids (such as healthy LDL particle size and distribution), better neurological health, lower risk of cancer, reduction in risk of metabolic syndrome, and improved autophagy (the cellular recycling of waste material and repair processes).

Paleo exercise

Our Paleolithic ancestors didn’t go to the gym to run on treadmills or bicycles. They didn’t play football or go rollerblading. Yet they certainly got plenty of exercise. Both modern exercise science and our evolutionary history suggest that some forms and ways of exercising are more conducive to health and optimal function than others. For instance, it’s highly unlikely that paleo people ran slowly for long distances. A paleo approach to exercise would include lots of walking and play, lifting heavy things (especially using compound movements rather than isolation movements), and occasional all-out sprinting. Aerobic fitness seems to be achieved much more efficiently and with lower risk of repetitive stress injuries by high-intensity interval training than by jogging for long distances.

Being highly regimented and regular in an exercise program can lead not only to boredom but to a declining level of physiological response. Paleolithic people didn’t exert themselves in exactly the same way every day. They might have to sprint at unpredictable times to catch food or to avoid becoming food. Some days they would have heavier burdens to carry or drag back to camp than on other days. Again, history and modern exercise science agree in recommending that you vary your exercise, mixing it up for variety, and frequently surprising your body with something new.

So that’s Paleo 101 for cryonicists who aren’t eager to dive into the dewar. My goal here has not been to convince you but merely to intrigue you and interest you in investigating further. The evidence for the paleo approach looks strong to me, based not only on the evolutionary rationale but also on the direct evidence.

My personal experience reinforces this. Despite having been following the paleo diet for less than half a year, I’ve gotten significantly leaner (my waist now back to where it was 20 years ago), my triglycerides have come down from an already good level, my HDL/LDL ratio has improved further, my health has been good, and my energy level has been noticeably more stable and my appetite less demanding. I believe that people who are overweight, diabetic, or suffering many other health challenges will benefit even more.

Further reading and resources

You will no doubt have many objections, doubts, and questions that I haven’t the space to answer here. Doesn’t saturated fat cause heart disease? Why do so many mainstream nutritionists (backed by the US government’s Food Guide Pyramid) promote a diet very different from paleo? Very likely, every one of your questions has been thoroughly addressed in one of the following sources.

Loren Cordain, The Paleo Diet.

Nora T. Gedgaudas, Primal Body, Primal Mind.

Mark Sisson, The Primal Blueprint.

Gary Taubes, Why We Get Fat.

Gary Taubes, Good Calories, Bad Calories.

Arthur de Vany, The New Evolution Diet.

Web resources:

Michael Rose’s video (about 38-minute mark on diet):