by Dave Asprey
As a former fat person, I knew that voice well. It’s the same one that sabotaged me every time I’d lose twenty or thirty pounds, only to gain it back and then some. It’s the one that wore out my willpower when I ultimately failed every diet I’d ever tried. Because I knew its power over me, though, I knew that if I was alone in a cave with no food, it couldn’t win, no matter how pissed it got. I tried answering it with a voice of reason, drawing on the words of Marcus Aurelius. The hunger was driven by fear, I told myself, not by a genuine need. The reality is, you can go for a very long time without food. In general, it’s going to take three months of eating nothing before you die.
The voice was lying, and I knew it. So no matter what your body tries to yell at you, it is just not true. I could safely ignore it and continue to pursue my better self. I doubled my vow that I would finally achieve power over the voice of hunger. But my vision quest was far from over. The voices in your head that lie to you do not give up so easily. Did I mention that they were trying to convince me I was smelling brownies?
MASTER OF YOUR ELECTRONS
I want you to read this chapter with a stout heart, intellectual rigor, and a mind for truthfulness. Embrace the philosophy of Marcus Aurelius1 (the Stoic part, that is, not the part with all the battles and throwing Christians to the lions, which had been fasted beforehand to make them extra ravenous). I want you to be able to look at what’s on your plate—or what’s not on your plate—and be okay with it. I want you to know that you are stronger than your fears and your cravings. I want you to know that your mind and body are full of untapped capabilities.
I want you to know that you’re capable of exercising on an empty stomach and emerging smarter, faster, and stronger.
From our primal days 300,000 years ago, when Homo sapiens was the newest hominid species in Africa, all the way up to the present, we humans have cherished strength. It’s how we survived in the wild. Sheer physical strength is no longer a daily matter of life and death for most of us, but being fit and active is still a measure of your ability to succeed and to enjoy the things you do. The importance of becoming stronger is built within us, starting at the subcellular level. The ultimate measure of strength is how many electrons your body can muster up quickly. So one of the first things your body does when you fast is get rid of the weak cells and grow more mitochondria—the metabolic power plants in the cells—through a process called mitochondrial biogenesis.
This regimen of cellular fitness training is the most foundational type of strength you can possibly have. When you fast, your ability to generate chemical energy increases. That improved efficiency allows your body to process even more fuel and generate even more energy. It’s like pressing the accelerator in your car. How quickly can you get power to the tires? Well, the first thing you want to do is have an engine that’s strong enough. Then you want to make sure that all the subcomponents delivering power from the engine to the transmission to the tires are also strong.
Fasting is like that. Intermittent fasting, in particular, strengthens your ability to deliver power, starting with the mitochondria and continuing up to the muscle cells, the neurons, the organs, and the body as a whole. When you get stronger at a subcellular level, you rebuild and improve yourself from the inside out. The end result is that you become stronger and more capable as a human being.
The other way fasting strengthens you is that it trains you not to waste energy. Ultimately, everything you think and everything you do is made possible by moving electrons from molecule to molecule. Fear and other negative emotions use up electrons. They direct your energy toward unproductive feelings and actions. Willpower uses electrons, too, so you want to apply it as efficiently as possible. Think of willpower as a mental muscle: you can exercise it. You can make it stronger so that you learn to fast and make it much easier to say no to cravings for muffins or potato chips or whatever junk you’re better off without. Once you train the urges of the body to be more obedient, they ask for less energy. You waste less energy on fear and insecurity, and then you need to invest less energy in willpower. Those changes all make you more powerful in general. It is impossibly liberating to be able to smile at your hunger, then head to the gym and get twice the results from your workout because you made your body take the harder path.
This process of cellular and mental exercise improves everything from your spirituality to your resilience to your emotional state—all the way up to your physical toughness. The goal here is that you want to know you can handle whatever life brings your way. Only you know exactly what that means, but regardless of what you face or what you want to achieve, fasting will help you get there. It lets you demonstrate to yourself that you can take control, and it demonstrates to yourself that you must. You will get stronger through fasting. You will get stronger through exercise. And if you approach both of them the right way, you will truly optimize your strength.
But first, you may need to make some radical adjustments to your beliefs about exercise and food.
STRIKING THE RIGHT SUGAR BALANCE
My relationship with working out is long and still evolving. When I started gaining weight in middle school, I honestly believed that exercise alone would keep me healthy and make me thin. That’s a flawed premise that many of us buy into. I played competitive soccer as a kid for thirteen years. Then I was a long-distance cyclist in mountain biking and road racing, entering a few races and completing several hundred-mile rides. I was only thirteen or fourteen and was doing the work, going the distance. And still getting fat and feeling like a failure.
In some ways, all that effort paid off. I enjoyed the training and discipline, constantly pushing myself to go farther and faster. But I was still gaining weight. There were things happening in my body that I just didn’t understand.
Anytime you engage in endurance exercise—a routine such as a run or a bike ride that lasts an hour or more or even playing a long game of soccer that involves constantly running up and down the field—your body will eventually run out of fuel. Back then, I did what everyone else did, filling my water bottle with sugary “sports drinks” in order to power up and keep going. I would eat a banana with a little bit of salt or some electrolytes and lots of sugary stuff in order to fuel myself.
I had also read enough to know you were supposed to eat a lot of carbohydrates the night before a big physical event. Back in the 1980s, we called that strategy “carb loading”; you would eat an exorbitant amount of bread and pasta to fill your muscles with glycogen to use as fuel. If you didn’t do that, everyone said, you would be susceptible to what we called “bonking.” There’s nothing sexual about that term; if anything, it’s the exact opposite. Every endurance athlete knows what I’m talking about. Bonking is the terrible feeling that can happen when your muscles run out of the stored sugar in your body.
Believe me, you don’t want to bonk. You start getting shaky. You have a feeling of nausea. You can’t think. Your brain shuts down, and you just want to curl up into a fetal position. You feel as though you have no power output left. And it’s not just an illusion. If you’ve never fasted, or if you haven’t built up your metabolic flexibility in general, the bonk is reality. You’re stuck, and the only thing that will unstick you is sugar. Your body doesn’t recognize any other fuel source, and it will take about four days for your body to start producing ketones by itself if you start fasting right then.
Even if you tried filling up on a steak instead of sports drinks (assuming you could somehow find a steak in the middle of a hundred-mile bike ride), that wouldn’t help with the bonking. If your body was trained to draw its energy from sugar, it will find a way to get that sugar. Eat a steak, and your metabolism will gladly transform protein into sugar on your behalf. Even worse, the dirty process of converting protein into sugar will unleash inflammatory by-products and lots of ammonia into your system. You’ll feel better slowly—that is, until the next time your muscles run out of glycogen. In the long term, you’ll also feel a relentless dra
g from all those toxins and inflammation.
Today, we have better approaches to staying well fueled during exercise. We have products such as stingers, gel packs, and energy chews. Stingers are small, crisp, honey-filled waffle sandwiches a cyclist or runner can ingest to keep his or her muscles topped off with glycogen. Honey is a sugary energy source that provides an instant energy boost. Gels and energy chews typically contain maltodextrin, a polysaccharide molecule that has an even higher glycemic (glucose-boosting) index than sugar. These things have their own shortcomings. Maltodextrin is derived from corn, rice, potato starch, or sometimes wheat, which can be a source of cellular inflammation. All three products rely on boosting your energy stores by using sugar or sugarlike products. There are also tons of sugar in all of the latest energy drinks. Whenever you eat sugar or carbs, your body will rapidly build up your glycogen store. It’s a quick fix.
If you take in too much sugar, you will run into other troubles. You can store glycogen in two places: the liver, where it is rapidly available and will be used preferentially by the brain, and the muscles. For every gram of glycogen your body stores, you also retain roughly three grams of water. That’s why heavy consumption of sugar and carbs produces a general look of bloating or puffiness. Beer drinkers know what I’m talking about. Your body has its energy and you feel good, but you haven’t built up your fundamental strength. All you’ve done is tapped into a short-term boost.
You are better than that. Or at least you will be soon.
BODYBUILDING FROM THE MOLECULES UP
Fasting enables you to build up your metabolic strength, and one of the most basic ways to do that is to break your craving for sugar. Some people liken sugar to cocaine, because there is an addictive nature to sugar and both give you a dopamine hit. Both are proven temporary energy boosters, and they’re both white powdery substances. The comparison is an oversimplification, but there is a kernel of truth in it.
Let’s be clear, no one’s doing lines of sugar. There isn’t a sugar-smuggling mafia selling it for $1,000 a pound, or whatever the going rate might be for a kilo of cocaine. (It’s not the kind of thing I keep track of.) On the other hand, look at the way the National Institute on Drug Abuse describes the effects of doing cocaine: “Small amounts of cocaine usually make the user feel euphoric, energetic, talkative, [and] mentally alert . . . and temporarily decrease the need for food and sleep.” Side effects include a racing heartbeat, irritability, seizures, strokes, and coma. Sugar does all of those things, too, just in more subtle ways.
And just as coke addicts cannot live without their lines, sugar addicts are dependent on sugar. A lot of people are hooked on sugar, and we can see the social consequences clearly in our exercise patterns. Every time you get a little bit tired during a workout, you probably take a hit of sugar. Even if you don’t exercise, you probably still keep taking regular hits of sugar. Managing fuel for short-term availability and short-term thinking has become our predominant metabolic strategy. There’s some merit to the idea of carb loading the night before an endurance task such as a long bike ride, but life isn’t a bike race, and the top racers today are starting their races running on ketones, not sugar! If you’re eating like a 1980s endurance athlete every day for the rest of your life, all that sugar will wreak havoc on your body. It will make you weak.
Let’s look at how you can become strong instead. What if you were to train yourself to switch effortlessly from burning sugar to burning fat? To most of the people at the gym, this probably sounds like a nutty concept. Sugar is energy. Fat isn’t energy. How can you possibly maintain a high-impact workout powered by fat? Well, it turns out that you can definitely exercise at a high level, and in a major way, running on fat. And when you switch to burning fat, some very interesting things happen.
Fat molecules actually contain more energy than carbohydrate molecules. The good types of fat are also anti-inflammatory, which is especially important during exercise. By its very nature, exercise is pro-inflammatory. Physical exertion tears away at your muscle cells and activates an inflammation response. That is why you feel sore after a hard workout. If you look at the blood markers of someone who has just completed a marathon or who has just done a heavy lifting session to exhaustion, there are clear signs of inflammation.
That’s not a problem, exactly. Inflammation is a natural and productive aspect of exercise. Your body gets stronger during the recovery cycle as it heals the inflammation and repairs your muscles at the cellular level. Muscle bulk is a by-product of that repair process. On the flip side, taking medication to reduce inflammation or even indulging in a simple ice bath halts this healing process and prevents muscular development. Even if your body aches the day after you do a hard workout, you’re better off not taking ibuprofen: it’s anti-inflammatory, so it’s actually working against some of your goals for exercising. Let your built-in repair mechanisms work the way they evolved to work, and your body will not only fix itself but make itself stronger.
If you really want to assist those mechanisms, take sugar out of the equation and use anti-inflammatory fat as a fuel source instead. Then you will jump-start the healing and strengthening process. You’ll be getting more energy and less inflammation at the same time. I was, to the best of my knowledge, one of the first people to stand up and say that it is possible to complete an Ironman triathlon in a state of ketosis, when the body is running mostly on fat-derived ketones. But there’s a huge caveat: I also said that it is stupid to do an Ironman triathlon in ketosis. It’s possible, but metabolically it’s going to be damaging. I have the proof. I’m not allowed to name names, but I talked with the doctor of someone who did an entire Ironman—2.4 miles of swimming, 112 miles of cycling, and a full 26.2-mile marathon—while in ketosis. As I predicted, his lab tests showed that he was a complete disaster. Inflammation everywhere. Metabolism in shambles. Ketones and carbs at the same time? Rocket fuel! That’s what I recommend.
The purpose of this book is to help you make the right choices with fasting, not take it to damaging extremes. Just because you can do something doesn’t mean you should. That applies to life in general, and it applies to fasting in particular. The goal is not to suffer or to push yourself to the absolute limit. The goal is to make you better, more energetic, more confident, stronger all around.
A central element of metabolic strength is metabolic flexibility, the ability of your cells to switch quickly and easily from burning sugar to burning fat. The mitochondria in those cells already contain all of the chemical tools to make adenosine triphosphate, or ATP, your primary energy storage molecule, from either sugar or from fat, but most of the time only one set of tools is activated. The vast majority of us are locked into burning sugar, including the loads of sugar we get from breaking down carbohydrates. If your cells are stuck in sugar-burning mode, it makes it harder to lose weight and limits the amount of energy you have available.
Exercise and fasting create unpredictability for your cells. They get biochemical signals that sugar is available only some of the time; other times, they need to be ready to run on fat. They need to be prepared for anything. In response, the cells adjust their compositions and their structures so that either type of metabolism is ready to go. In addition to helping you with weight loss and energy gain, flexible cells do not develop insulin resistance and adapt easily to ketosis without making you feel lousy. By analogy, think about a phone that you can charge from a wall outlet but also from a cable in your car. If you could charge your phone only one way, you’d be really limited. A phone that can power up wherever you go is much more useful, reliable, and enjoyable—just as you want to be.
FASTING AND EXERCISING TOGETHER
Now let’s think through a smarter way to exercise using your own fat as your fuel, because ketones are anti-inflammatory and more energy dense than sugars and carbs.
Even as I write this book, I’m reading about Ironman triathletes, hundred-mile ultramarathoners, and other extreme endurance athletes who are learning to
burn fat as they compete. They’re not doing it in an all-out state of ketosis. Rather, they break their ketosis before or during the race with a small amount of carbohydrates. A minidose of carbs keeps their muscles filled with glycogen, but it also allows them to metabolize fat as a more potent fuel and hydration source. They train while in ketosis whenever they can, but they regularly exit ketosis and eat carbs and protein in order to raise their testosterone level. And then, when they are going to compete in an event, they start out the race with lots of glycogen and a metabolism that is happy to take energy from sugar or MCT oil and ketones.
Now, that is a regimen that I can endorse. It’s an intelligent way to combine fasting and exercise to maximize their mutual benefits, the same way you learned how to combine sleep and exercise in the previous chapter. Start with a mild fast before you exercise, whether it’s weights or high-intensity interval training. The best time to exercise is at the end of a fast, so for most of us doing intermittent fasting, it’s around 1:00 or 2:00 p.m. After the exercise, when your body is primed to repair and build muscle, break the fast. Have some protein. Have some fat. If you want to exit ketosis, have some carbohydrate, too. Your workout will have been harder because you were fasted, but your results will be far greater, and the food will taste better after your workout.
If you’re doing a long-endurance event, supplement your ketones in the form of C8 MCT oil—more than a few pro athletes use Bulletproof Coffee and amino acids such as L-glutamine. L-glutamine takes you out of ketosis, but it’s quick energy, and your goal in a race isn’t to stay in ketosis. Your goal is to have maximum energy from all pathways, including ketones, glucose, and amino acids. It’s okay to have your favorite carbohydrate source, especially in the second half of the event. Your body is going to do better.