by Dave Asprey
So I turned to a raw vegan diet, and I went all in. I bought sprouting trays and the world’s best blender and spent my days eating bowl after bowl of salad and entire blenders full of green smoothies trying to consume an adequate number of calories. It worked … for a little while. I got down to about 185 pounds—too low for a six-four guy—and I felt a burst of energy that also made me feel flighty and ungrounded. I convinced myself that the increase in pain and stiffness that came with this was just my body “detoxing.” But my friends said I looked gaunt, and pretty soon I wasn’t feeling so great. My teeth got sensitive and even started to break, and I felt cold all the time. It was pretty clear that I was suffering from malnutrition, despite knowing a ton about nutrition and spending two hours a day preparing food.
Later I learned about what I call the “vegan trap.” When you switch from a diet containing animal fats to the mostly omega-6 polyunsaturated fats found in plants, you set yourself up for failure. Vegetable oils reduce your thyroid function by preventing thyroid hormone from binding to receptors.10 At first your thyroid hormones will temporarily increase to compensate for the lower energy, and you feel good. That’s what led to my ungrounded energy and initial weight loss. But if you continue to give your body the wrong building blocks, your health will suffer. Because your cells don’t have the right building blocks to make energy efficiently, your metabolism eventually slows down. That slow metabolism doesn’t just make you gain weight more easily; it slows down your brain, your energy, and everything you do.
For about six weeks as a vegan, I felt great and grew convinced that my diet was the answer to all my problems. I had tons of energy and no idea it was the energy of a stressed animal that is starving and needs one last boost to catch its prey. Already convinced that being a vegan gave me more energy, I logically decided to “lean in” when I started to feel the ill effects. That is why it’s a trap—once you’re convinced that you feel good on a vegan diet (because you actually did for a short while), you don’t think to look at your diet when your energy or your health begin to suffer.
Thankfully, it took me only about six months to realize what was going on, do more research, and decide to add meat back into my diet. By then I had learned about the dangers of consuming AGEs when eating overcooked meat, so for a brief period of time I became a raw omnivore. In addition to occasionally eating sushi, I marinated thin strips of steak in apple cider vinegar to kill harmful bacteria and added it to my salads. With that plus some raw egg yolks and raw butter, I started to feel better right away.
When I reread The China Study, I realized it had some serious flaws. For example, the researchers conclude that all animal protein causes cancer simply because rats that were exposed to large amounts of casein (a dairy protein, one of thousands of animal proteins that each do different things) had a higher chance of developing liver cancer than rats that did not consume casein. But the study didn’t account for the type of animal product or the type of animal; nor did it consider what that animal ate or how the meat was stored or cooked. These factors truly determine whether or not an animal product is aging. So does the amount of meat you eat. If you want to live a long time, you want to avoid eating too much meat and avoid eating all low quality meat.
My time as a raw vegan was not fun, but I am grateful for The China Study. Had I not cut out animal protein from my diet, I wouldn’t have become familiar with the research showing that most of us—including me before I went vegan—eat far too much protein in general. Eating a pound of steak or chicken every day has a different impact from eating a few ounces, which in turn has a different impact from eating none at all.
After I started eating meat again, I wondered why my inflammation levels had decreased when I cut out animal products. It turns out excess protein—especially from animals—causes inflammation. Most animal protein contains specific amino acids such as methionine, which causes inflammation and aging when eaten in excess. (Except for collagen protein, which has far less methionine.) In pharmaceutical studies, this is called an inverted U-shaped response curve. It means there is a “Goldilocks zone” for dosing a substance, and either too little or too much does not work.
This is no small consideration. When you eat a diet high in animal protein, you can expect a 75 percent increased risk of dying from all causes over eighteen years, a 400 percent increased risk of dying of cancer, and a 500 percent increased risk of diabetes compared to someone who restricts his or her animal protein.11 Totally not Super Human. Another set of studies found that restricting protein can help increase maximum life-span by 20 percent, probably because less protein means less methionine.12
The type of protein you eat is as important to consider as how much protein you eat. If the protein in question is charred or deep-fried, there is no good amount to eat. Same goes if it’s from industrially-raised animals treated with antibiotics. But if the protein is from gently cooked grass-fed animals, wild fish, or plants (hemp is best), then there is a simple formula for the correct daily allowance: about 0.5 grams per pound of body weight for lean people; and about 0.6 grams per pound for athletes, older people (the risks associated with overconsumption of protein decrease after age sixty-five), and pregnant women.
If you’re obese like I was, sorry, but all that extra fat you’re carrying around doesn’t require protein, so subtract it from your body weight before figuring out how much protein to eat. For instance, when I weighed 300 pounds, let’s assume I was carrying an extra 100 pounds of fat. Take my weight (300), subtract my fat (100), and you end up with 200 pounds, so I should have aimed to eat 100 grams of protein (0.5 × 200 pounds). If you’re relatively heavy and have no idea of your body fat percentage or are just bad at math, assume you’re about 30 percent fat. So you’d eat 0.35 grams per pound of body weight.
Collagen protein is a special case. Given that it lacks the most aging amino acids and has all sorts of benefits for connective tissue, you can add another 20 or more grams of grass-fed collagen on top of your protein intake or use it as part of that number. Some days up to 50 percent of my protein comes from Bulletproof collagen.
Eating less protein will not give you less energy. Contrary to everything you’ve heard from most popular diets (even keto), protein is actually a terrible last-ditch fuel source for humans, worse than fat or carbohydrates. The process of turning amino acids from protein into energy creates a lot more waste than fat or carbs, and excess protein ferments in the gut and produces ammonia and nitrogen. This puts a huge load on the kidneys and liver. Instead of getting energy from protein, you want to consume just enough protein as building blocks to repair your tissues and maintain muscle mass, and then get energy from fat, fiber, and a few carbs, instead.
When you get this right, your cells can rebuild themselves with clean animal fats and protein (notice, you’re an animal, too), and your gut bacteria will actually transform fiber from vegetables into fatty acids, an ideal fuel source for your mitochondria. Add in excess protein, antibiotic-contaminated meat, and/or sugar, and your gut bacteria just won’t do the same thing.
Restricting protein intake also helps boost autophagy, your all-important cellular recycling program. By occasionally limiting how much protein you eat (you can still have a nice steak every once in a while), you force your cells to find every possible way to recycle proteins. In their search, they excrete waste products hiding in your cells, slowing down energy production. Temporary protein deficiency is a type of hormetic (beneficial) stress. In response to protein restriction, your body looks for other sources of energy. It is the equivalent of burning your trash to stay warm.
The same thing happens when you use intermittent fasting (simply eating all of your food within a shortened period of the day, usually between six to eight hours) as a type of hormetic stress. Intermittent fasting is incredibly useful in aiding fat loss, preventing cancer, building muscle, and increasing resilience. Done correctly, it’s one of the most painless high-impact ways to live longer.
Until re
cently, we did not fully understand why fasting was so beneficial. Then in 2019, scientists at the Okinawa Institute of Science and Technology discovered that just fifty-eight hours of fasting dramatically increases levels of forty-four different metabolites, including thirty that were previously unrecognized.13 Among other beneficial functions, these metabolites—substances formed during chemical processes—boost antioxidant levels in the body. And as we know, antioxidants are important for fighting off aging free radicals. All of these benefits can be explained by the fact that fasting dramatically boosts autophagy,14 keeping your cells young and healthy.
Fasting has profound effects, even at less than fifty-eight hours. Alternative day fasting, a form of intermittent fasting in which you eat every other day, helps prevent chronic disease and reduce triglyceride and low-density lipoprotein (LDL) cholesterol levels in as little as eight weeks.15 Intermittent fasting also increases your brain’s ability to grow and evolve by boosting neuronal plasticity (the brain’s ability to change throughout your life) and neurogenesis (the birth of new neurons).16 This can help ward off Alzheimer’s and cognitive decline.
As you might expect, when I started experimenting with intermittent fasting ten years ago, I was often left feeling cranky and cold around lunchtime, before my eating window opened. This is because I had not yet developed the metabolic flexibility from teaching my body to efficiently burn carbohydrates or fat. Today I can effortlessly fast for twenty-four hours because my metabolism is younger and my blood sugar levels have stabilized. Thankfully, there are now well-understood ways to make intermittent fasting painless, which you’ll read about later.
A BIG FAT LEAP OF FAITH
So, when it comes to aging, grains are bad, sugar is bad, fried stuff is bad, and too much or too little protein is bad. What about fat? Can you eat too much of it? Sure. But we need fats for reproductive health, temperature regulation, brain function, and shock absorption. Fat helps build the outer lining of your cells, which protects them from damaging substances. It also makes up the bile acids you need to digest foods, and vitamins A, E, D, and K are fat soluble, meaning your body needs fat to absorb them. Additionally, several important hormones, including leptin, which helps you feel satiated, are made from saturated fat and cholesterol. Fat is also the basis for the lining of your nerves, called myelin, which allows electricity to flow efficiently between nerves and is essential for avoiding degenerative diseases like multiple sclerosis.
Saturated fat in particular is so important that your body converts carbs to palmitate, a type of saturated fat, in a process called de novo lipogenesis. Without this ability, you’d die. That’s how critical saturated fat is. Your body then converts palmitate into other saturated and monounsaturated fats necessary for cell membranes, but it can’t make enough polyunsaturated omega-6 and omega-3 fats. That’s why you have to eat them. Yet the myth that eating fat and cholesterol will make you fat and give you heart disease still somehow persists. You read earlier that it’s your gut bacteria and not dietary cholesterol that creates plaques that build up in arteries. The evidence is in, and the fats you eat that contain cholesterol are not the enemy, as we’ve been told.
When you eat enough of the right fats without excess carbs or protein, your body learns to efficiently burn fat for fuel. If you eat excess carbs or protein, your body burns those first. Normally, your body converts carbohydrates to make glucose, which your mitochondria use to produce energy. When you run out of carbohydrates, you start converting fat to glycerol for energy. The liver produces ketones as a by-product of this fat metabolism, and your mitochondria burn those ketones instead of glucose in a more efficient form of energy production. Ketosis is a state your body enters when you have a lot of ketones in your blood and are burning additional fat … or when you eat a special type of saturated fat that converts to ketones in your body. More on that later.
One last time: Your body requires fats for you to perform your best and live as long as possible. You just have to know which fats serve what purpose. Some fats you eat are building blocks for your body, and some are better used as fuel. Getting the mix right matters. But have you ever heard nutrition “experts” say exactly which of the many saturated (or other) fats to avoid? The typical buckets you hear (“plant based,” “animal fats,” “saturated,” “polyunsaturated”) are not very specific. Is it possible that the heated industrial polyunsaturated fat in French fries has a different effect on your biology than avocado oil, or that the fat in industrially-raised animals is different from the fat in an egg yolk or pastured beef? You bet it is.
Researchers in Australia have measured how different cells elegantly use each type of fat you eat. You can make sure your brain has the type of fuel it runs best on and that your body fat doesn’t create extra inflammation and make you old. Eating the right fats could add productive years to your life, which is why it’s worth a page or two of your time to dig a little deeper into details of how your body uses fats.
Scientists describe cell membranes as “the margin between life and death for individual cells.”17 These membranes are made of tiny droplets of fat. About 5 percent of your genes contain instructions telling your cells how to make the thousands of types of fat your body needs to survive. We now know so much about what each different type of fat does that French researchers have proposed the notion that “saturated fats should no longer be considered as a single group in terms of structure, metabolism, and functions.”18 In other words, we have grouped together a very diverse array of fats under one reductive and often misleading label. When your doctor tells you to eat less saturated fat, your response should be “Which one(s) do you mean?”
I’ve had the opportunity to interview lots of fat experts (or experts on fat), and most of us use an analogy from nutritionist and early trans fat researcher Mary Enig, PhD, who popularized two basic ways of thinking about the fat you eat. The first is to look at how long a fat molecule is. There are short-chain, medium-chain, and long-chain fats. As a general rule, the shorter the saturated fat, the more anti-inflammatory it is. For instance, butyric acid, which is anti-inflammatory, has only six molecules, while other types of fat may have twenty or more.
Some fats are easy to damage no matter how long they are. So the second way to understand your fat is to assess its stability. Oxygen drives very strong chemical reactions that damage fats through oxidation. Oxidized (damaged) fats cause you to age more quickly by creating inflammation in the body and building less effective cell membranes. When your body has no choice but to incorporate oxidized fats into cell membranes, those cells create excess free radicals that make you an average human, not super.
Your cells use saturated fats, which are the most stable of the fats, to make about 45 percent of the cell membranes in the brain and liver, and about 35 percent in heart and muscle cells.19 Yes, saturated fat is the dominant fat in your brain, so don’t demonize it! Energy-producing cells will hold their level of saturated fat at about this level no matter what type of fat you eat. The only type of tissue that meaningfully changes its composition of saturated fat is adipose tissue—aka your muffin top. When you eat more saturated fats, the cells in adipose tissue will change their makeup to contain more saturated fat and less unstable fats without changing in size. This is fantastic, as stable fats make for fewer free radicals.
Think of saturated fat as the stable waxy bricks building the “walls” for your cells. The problem is that your cell membranes have to flex in order to make energy and receive chemical signals, and those nice stable saturated fat “bricks” don’t bend. So while it’s fine to go ahead and eat butter and other forms of saturated fat, it’s also important to eat other types of fats. And those include the next most stable group of fats, monounsaturated fats. These fats—found in food sources like olive oil, avocados, and some nuts—are more flexible than saturated fats. You can think of them as the gel-like “mortar” that supports your saturated fat bricks in the cell wall. Your cell membranes are made up of about 20 percent mono
unsaturated fat.
Interestingly, brain cells have the most monounsaturated fat of any cells in the body, and they hold their level of monounsaturated fat constant no matter what types of fat you eat. Most other cells adjust their fat content slightly when you eat a lot of monounsaturated fats. But without changing how much fat you have on your body, fat cells will happily dump other stored fats and replace them with monounsaturated fat. This means you can transform your stored body fat to have a higher percentage of stable fats. Eat your olive oil!
After you account for the saturated and monounsaturated fats in the membranes of energy-producing cells like muscle, you’re left with about 35 percent of a combination of polyunsaturated omega-6 and omega-3 fats, as well as some conjugated linoleic acid (CLA), a type of fat produced by microbes in your gut. (CLA also happens to be found in grass-fed butter—more on this in a bit.) While omega-3 and omega-6 fats fall under the same category, they are not the same.
Omega-3s are anti-inflammatory and thus beneficial to your anti-aging efforts. The best omega-3 fats are found in food sources like cold-water fish (salmon, mackerel). You can also get omega-3s from walnuts and olive oil, but vegetable omega-3s are only 15 percent as effective as those found in fish.20
Unfortunately, omega-3 fats are far outnumbered by omega-6s in the standard Western diet—and omega-6 fats are highly inflammatory. Poultry, the most common protein in Western diets, is high in omega-6s. Most refined vegetable oils are also polyunsaturated omega-6s, and they are so unstable and inflammatory that eating excess canola, corn, cottonseed, peanut, safflower, soybean, sunflower, and all other vegetable oils is likely to contribute to cancer and metabolic problems. Oxidized omega-6 fats damage your DNA, inflame your heart tissues, raise your risk of several types of cancer, and don’t support optimal brain metabolism.21 Anything that increases inflammation decreases brain function.