Fast This Way

by Dave Asprey

  The act of fasting did not diminish the body’s evolutionary adaptations. Instead, it encouraged them. In effect, we became smarter by not eating for a while and then eating fatty animal foods to power our brains. You may feel panic if your next meal is more than six hours away, but your body knows better. When you don’t eat for a while, the brain simply switches from running on glucose to running on ketones. The switchover, which can occur as soon as you go fourteen hours without consuming food, but most often in twenty-four to forty-eight hours, happens automatically and almost imperceptibly—at least it does once your metabolism becomes accustomed to this type of switching. When you’re new to burning fat, the switch takes two to four days, and in the meantime, you don’t feel great. This book contains the things you need to know to skip that painful process. They are things our caveman ancestors simply didn’t have access to because they didn’t have the ability to modify their food that we do.

  Fasting unleashes your hidden evolutionary powers. Ketones have more electrons per gram—more raw energy density—than glucose. When you pour ketones into your cells, it’s as if you went to the gas station and put in high-octane racing gasoline. Because fat has more calories per gram than sugar, your body can metabolize ketones to produce more heat per gram than glucose. Mixing metaphors: eating fat instead of sugar is like drinking a vodka instead of a beer (although in this case, it’s okay to drink and drive!). It has a different effect on you, because it is so much more potent.

  There’s a reason animals fast when they get injured. Whether you realize it or not, humans do this, too. The last time you were really sick, did you have an appetite? Our body naturally reduces our need for food when we’re ill, allowing it to spend its energy on repair rather than digestion and heal itself without the presence of toxins. The same thing happens when you take long breaks between meals. Fasting activates a built-in adaptive healing process.

  Think about that the next time you fear dying if you miss lunch.

  THREE MEALS A DAY? WHY?

  After cooking, the next revolutionary change in the human diet occurred roughly 10,000 years ago, when Homo sapiens learned how to farm. Instead of roaming the savanna on foot, searching for meals, and eating with large breaks between unpredictably timed meals, we became tied to the land and to our herds of domesticated animals. We became anchored to one location, because if we left that would mean the end of our farm. The villages that grew around farms needed workers for various jobs, and soon we stopped moving and started sitting a lot more. After more than a quarter of a million years of routine fasting, the new food supply that we grew on small plots of land meant we could eat a meal a day, every day. Then as we got better at agriculture, it was possible to plan on two meals. The modern routine of breakfast, lunch, and dinner is less than two centuries old.3 Later on, we added nachos and potato chips in between those meals, while watching television.

  Abundant food should have made it possible for all of us to be creative geniuses. Perhaps those early farmers also planted the seed for CICO diets because they swapped meat and fat calories from animals for abundant amounts of carbohydrates from plants. In one fell swoop, they killed fasting and replaced the highest-nutrient foods with corn and wheat. This is a great system, at least if you’re one of the lucky few at the top. All those dull minds could toil in the field, which freed the elites to explore arts, science, and chemistry and also get the best, most expensive food—from grass-fed animals, instead of having to spend the day hunting. But if you were one of the majority working in the fields, you led a dull, nutrient-deficient life. The new diet even led to a decline in the average height of humans, because much of the time we were at war with our own biology.

  Starting in the early nineteenth century, with the advent of the Industrial Revolution, people in the Western world all began eating more or less on the same schedule. Before that, the concept of time wasn’t as regimented. You didn’t need to know exactly what hour of the day it was; farmers just cared about when the sun rose and set. After the Industrial Revolution, though, a pocket watch became an incredibly valuable item, because it told you when the trains were going to arrive and depart. Trains ran on precise schedules. Then factories and stores ran on precise schedules. Our new connection to time, which was driven largely by train schedules, led us to start planning our meals for specific times each day. We scheduled our food around trains, not our actual hunger or the needs of our bodies.

  Let’s go back to that metaphor of putting gas in your car. What if someone told you that you would have to drive to the gas station every Tuesday and Thursday at 3:00 p.m. to put ten gallons of gas into your car. Why? There’s no explanation; you just know that everybody does it, so it must be the normal thing to do. It doesn’t matter where and when or how much you have driven your car. It doesn’t even matter if your tank is empty or full. Every Tuesday and Thursday at 3:00 p.m., you fill the tank. That’s just the way it is.

  Sometimes you go to the gas station, put the nozzle in, and the tank is already full. You always buy ten gallons, though, so you just pump the gas onto the ground or maybe put it into a separate little storage can in the trunk. Huh, this is getting weird. Still, there must be a reason it’s the tradition, right? Pretty soon your car is full of extra gas in the trunk that you don’t need. Now you’ve got junk in your trunk, you might say. Eating the same-size meal at the same time every day makes no rational sense, no more than filling your car with gas on that nutty schedule does. If you’re not careful, it really will put junk in your trunk. But it’s tradition, so we generally go along without even thinking about it.

  A lot of our weird attitudes about food have emerged from the clash between our evolutionary origins and our modern cultural traditions. Eating is essential to survival, yet it isn’t only a biological imperative; it’s a sensual experience and a communal ritual. Cooking for and feeding one another is an intimate act, a spiritual act. It relieves stress even as it puts fuel and nutrients into your body. Our big brains need lots of energy, but they also need periods of fasting and regeneration. On the other hand, the social structures and the food industry created by our big brains keep telling us to eat regular meals—to eat whether or not we’re hungry—so we keep craving food all the time.

  But as we know, in addition to energy and nutrients, food fills you with toxins. We learned to focus on satisfying our energy needs above all else, because that was (and is) how we stayed alive. Next we learned to focus on flavor, because a good taste was (and sometimes still is) an indicator that a food was nutritious and high quality. But we’ve never really learned how to avoid toxins, unless they kill us or disable us quickly. The subtle, slow-working toxins in food are difficult to recognize. And frankly, for almost all of history, when faced with the choice between famine and eating food that has calories along with some toxins, we have rationally chosen to take the hit from the toxins. Sometimes they even taste good!

  One surprising example is rice. Brown rice has more calories and fiber than white rice, but in the countries where rice is a historical part of the diet, people always ate white rice when they could afford it. Brown rice was long considered peasant food. Why? Everyone knew that they didn’t feel as good when they ate brown rice because it’s hard on the gut. Today, we know it contains lectins, those nasty plant toxins that keep animals from eating rice, and about eighty times as much arsenic as is found in white rice. That’s why white rice exists: it was milled to get rid of the toxins in the husk. Then modern science stepped in and ignored the toxins, instead praising the extra fiber and nominal amounts of vitamins in the rice husks. Health food experts told us to eat brown rice because it has more good stuff in it. The hidden cost in gut irritation from lectins, arsenic poisoning, and cravings wasn’t in the equation. After you eat brown rice, do you notice a “food baby”—a little swelling in your stomach?

  Whenever you experience inflammation, it means that some electrons that were supposed to power your body instead went into inflammation. Your body will
want you to eat more to make up for the lost electrons. Try it yourself. Brown rice keeps you full for a little longer because it is hard to digest, but after that, big cravings come. White rice is digested quickly but without the cravings. Our ancestors knew that the extra nutrients in brown rice aren’t worth the trouble that comes with the toxins you get. If you think rice is confusing, just ponder all of the sensory overload and conflicting information that hits you when you’re walking down the aisles of the supermarket. Your poor brain wasn’t evolved to handle this.

  Your brain says: the most important thing is to make sure I get tons of energy, because I might not get another meal. That weird visceral programming happens before you have a chance to think about it, unless you bring your brain back to its baseline through fasting.

  Or let’s use another example: a cookie. Your body has an automated system to make sure that you never, ever run out of energy. If you could somehow take control of the automated system and make it consciously visible—if you could look at the cookie like Neo from The Matrix, seeing the zeros and ones that represent your body’s operating system—you would see that the cookie contains lots of energy. Do you need energy right now? Perhaps not, but your brain knows that the energy will make you feel good. Does the cookie have nutrients in it? Maybe, maybe not, but that’s okay. You can take a supplement if you want nutrients, and some of the other foods you eat will probably balance it out. Even if you have a very basic supplement budget, you’re not going to run out of nutrients.

  But does the cookie also have toxins in it? Your brain has no idea, and unless you’ve read and decoded the ingredients (or made the cookie yourself), you probably have no idea, either. In the absence of information, the evolution-honed message you get from your brain is: go ahead, eat. What you’re going to find very quickly is that your body tells you to eat everything, including foods that are full of toxins and things that have more energy than you actually need. And the toxins themselves cause more food cravings when they slow down your mitochondria.

  You’re left asking yourself, “Why does my body want me to eat that cookie?” It’s not a rational impulse. In fact, it’s fueled largely by emotion. Remember, we all want to feel safe. We all want to feel loved. There isn’t a better way to feel loved and safe than to be a baby nursing on your mother’s chest. That wiring is still in there, hidden beneath your thoughts. No wonder fasting pushes your buttons.

  We all have an emotional association with food. Some of us take it a step further by using food as a form of comfort or a passionate connection. That’s one reason why I ended up in the cave. I wanted to make sure I dealt with my emotional attachments to food as a part of my journey. I wanted to completely understand why the hell I kept putting food into my mouth, even when I knew I didn’t want or need it, even when my body was distorted by stretch marks. These kinds of revelations are not easy for me to write about, and I’m sure they’re not easy for you to think about, but they’re real. You must confront them in order to embrace them and, ultimately, free yourself from them.

  Nourishing someone is an intimate act. Nourishing yourself is an intimate act. You’re literally taking something from the environment, putting it inside you, and absorbing fuel, nutrients, and toxins from your digestive tract to make that food become part of your body. As humans, we have all kinds of emotional baggage connected to the act of eating. Most of it is preconscious, because each cell in your body wants you to eat, independent of you actually wanting to eat. In the modern world, food is so abundant that the want can be activated all the time—unless you train yourself to activate the feeling of going without while still feeling safe and loved.

  You are constantly hearing a dialogue between your biology saying that if you don’t eat, you’ll die, and your adult, conscious, evolved human brain saying that it needs food to feel safe. But you don’t have to listen. Keep telling yourself: neither message is true.

  THE PRICE OF PLENTY

  The modern era of abundant food means that much of the world no longer has to worry about the famine and starvation that threatened our species through most of its history. All of this plenty comes with a significant trade-off, however, in our loss of fasting and all of the benefits it provides.

  Mark Mattson, a neuroscientist at Johns Hopkins University and the former head of the Laboratory of Neurosciences at the National Institute on Aging, summed up this dilemma in a 2014 review article, “Challenging Oneself Intermittently to Improve Health.” He came to largely the same conclusions that I did in the cave. “As a consequence of the modern ‘couch potato’ lifestyle, signaling pathways that mediate beneficial effects of environmental challenges on health and disease resistance are disengaged,” he wrote. “. . . Reversal of the epidemic of diseases caused by unchallenging lifestyles will require a society-wide effort to re-introduce intermittent fasting, exercise, and consumption of plants.”4

  In the early days of agriculture, crowded working conditions and proximity to domesticated animals, as well as concentrated human waste in villages, ushered in an unprecedented number of deaths from parasites and infectious diseases. The list included many of the diseases that show up in the earliest recorded history, such as cholera, typhoid, leprosy, smallpox, malaria, tuberculosis, and herpes. We passed diseases to our animals, and in time they gave them right back to us. In due course, Homo sapiens traveled away from Africa into the land we now call Europe, where they interbred with the closely related Neanderthals who had already migrated there. The two shared diseases, and there is some evidence that the infections we carried helped wipe out the Neanderthals.

  Early farmers didn’t eat at the same time every day. It took factories, trains, and the Industrial Revolution to regiment our eating habits. Until we started eating three meals a day, the chances of dying of high blood pressure, insulin resistance, heart attack, and cancer were significantly less than they are today. Overeating and obesity were almost nonexistent for thousands upon thousands of years. Nowadays they qualify as global pandemics in their own right. Cardiovascular disease kills an estimated 18 million people a year. More than 400 million people worldwide suffer from diabetes, according to the World Health Organization.5

  Intermittent fasting is a way to restore balance. It can set your evolutionary self into harmony with your modern self, easing the tension inside you.

  I often find it funny that so many people regard intermittent fasting as a new and controversial idea. It’s more like a deep human wisdom that we’ve lost and now need to recover. The practice of deliberate fasting dates back thousands of years and has long been associated with wellness, longevity, and personal growth rather than mere denial. Fasting is a central element of Ayurveda, the system of health developed in India three thousand years ago. The ancient Greek philosopher Pythagoras used fasting as a path to enlightenment, reportedly requiring his students to fast for forty days before their exams. Paracelsus, a sixteenth-century Swiss physician who was a leader in the medical revolution of the Renaissance, proclaimed fasting to be “the physician within.” In the late 1800s, the American physician Edward H. Dewey tried to revive these ideas by promoting a fast-based “no-breakfast plan” in his wildly popular book The True Science of Living. He claimed that nearly every modern disease is caused by “more or less habitual eating in excess.”6 Yup.

  The story is the same among many indigenous American cultures. Native American tribes practiced fasting in both private and public ceremonies. In some First Nations tribes, this process began at puberty, with a solitary time of fasting and praying that lasted from one to four days. For adults, fasting preceded important events such as hunting or war. There were even occasions when entire tribes would fast together to enhance their sense of community. One Cherokee spiritual leader explained fasting “as a means to spiritualize the human nature and quicken the spiritual vision by abstinence from earthly food.”7

  Over the course of history, almost every world religion has made a similar connection to fasting as a means of enhancing spi
ritual development. The Christian, Jewish, Muslim, Buddhist, and Hindu faiths all advocate a period of fasting to attain spiritual enlightenment. In the Old Testament, Moses and Daniel fasted to enrich their faith. Later on, Jesus would fast forty days and nights in the desert. Traditionally, Catholics fasted from meat on Ash Wednesday and Good Friday and often at other times during Lent. Jews fast on Yom Kippur as a way to reset their relationship with their community and with God. The Muslim holy month of Ramadan has fasting as one of its cornerstones, with the faithful abstaining from all food and drink between dawn and dusk.

  Across the religious spectrum, many orders of monks enhance their already ascetic lifestyle by eating nothing after noon each day. Memorably, Mohatma Gandhi fasted for political reasons on at least fourteen different occasions, with three of the fasts lasting at least twenty-one days each. At those times, he lived on nothing but water and salt. “What the eyes are for the outer world,” he said, “fasts are for the inner.”

  It makes sense that a highly evolved brain, freed from preoccupation with obtaining food and fueled by energy-rich ketones, would be primed to explore the highest aspect of its cognitive powers. But the spiritual side of fasting did not lend itself readily to scientific investigation until recent improvements in neuroscience. Even without electrodes, anyone experienced in meditation and fasting will attest that different levels of consciousness are much easier to attain when fasting. One of those elevated levels is called Samadhi. In Hindu yoga, Samadhi is a deep level of ecstasy and superconscious perception in which people feel themselves become one with the entire universe, merging into God. Fasting expedites this process.

  In other words, I wasn’t being a kook when I decided to go into a cave and immerse myself in a fast. Sages all through history have done similar things in their search for enlightenment and self-realization. I may not be anywhere near the level of history’s great sages, but sitting in a cave and fasting really does work. How much of it was the physical environment of the cave, how much of it was the solitude, and how much of it was the fasting? That I can’t tell you, but I definitely walked out of that experience a changed man.