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Fast This Way

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Fast This Way: Burn Fat, Heal Inflammation, and Eat Like the High-Performing Human You Were Meant to Be
By Jonathan Roseland

I'm not a doctor, medical professional, or trained therapist. I'm a researcher and pragmatic biohacking practitioner exercising free speech to share evidence as I find it. I make no claims. Please practice skepticism and rational critical thinkingYou should consult a professional about any serious decisions that you might make about your health. Affiliate links in this article support Limitless Mindset - spend over $150 and you'll be eligible to join the Limitless Mindset Secret Society.

Book Review: The edifying economic biohack (that you may not be getting right...)

I've been fasting for years, in fact, it's a major economic lifehack, so I decided to read Dave Asprey's recent deep-dive book on the topic, Fast This Way. The book is a bit of a memoir actually, it's punctuated by vignettes from a grueling (and transformative) 4-day fast that the author did alone in a cave in the Arizona desert.

Why does fasting work?

How can fasting do so many good things for you? The answer is simple: your body is already packed full of repair and rejuvenation mechanisms. Thousands of years—no, millions of years—no, billions of years of evolution have shaped them inside of us. Your ancestors have run the gauntlet of death and extinction. You and I are the survivors of an inconceivably brutal winnowing process. We wouldn’t be here if we didn’t have all of those health-preserving cells and molecules. All that fasting does is remove the dietary impediments we put in our own way and allows us to take maximal advantage of the gifts evolution has given us. Fasting puts us in control of a 4-billion-year-old evolutionary process. (pp. 97-98)

there’s a fundamental difference between hunger and craving. Hunger is a biological message, and it is something that you can control. Craving is a psychological psychological need, and it is something that tries to control you. The truth is, you can go a long time without eating, and you won’t suffer for it. In fact, you will thrive. (p. 4)

Fasting is an amygdala hack

But as essential as the amygdala may be, it can also be a source of irrational, destructive fear. It’s a major contributor to that voice in your head that says you might just die if you do something you’re afraid of—such as going on a job interview, ending a bad relationship, speaking in public, or simply skipping a few meals. Intermittent fasting enables you to put the amygdala and the whole reptilian part of your brain in its place, so that you can be more fully human, more fully yourself, less burned by your fears. (p. 7)

Fasting is really the best spice!

When you end a fast from anything, it makes that substance or that experience much more appreciated. It causes heightened pleasure and brings easy gratitude into your life. (p. 13)

I'll second this! Fasting is reliably a hedonism hack, before I meal I know I'll love, I'll fast to multiply the pleasure.

Fasting for COVID resilience

Adrienne Barnosky, an endocrinologist at Duke University School of Medicine, and her colleagues confirmed that intermittent fasting helps prevent insulin resistance. (p. 16)

As explained in Dr. Mercola's recent book, insulin resistance is a major risk factor that puts you in danger of a catastrophic case of the wu-flu.

Bulletproof coffee is recommended relentlessly throughout the book...

Which I don't have a problem with, it can be a game-changer for fasting. I drink Bulletproof-style coffee almost every day and it powers me through my intermittent fast. 

Wake up in the morning and drink a cup of Bulletproof Coffee: black coffee, a dollop of grass-fed butter, and a teaspoon or more of C8 MCT oil. It’s the best latte you’ll ever drink. (p. 18)

And you don't have to buy Bulletproof products; just add butter and MCT oil to quality organic coffee, and your fast will be a whole lot less arduous.

On dieting

Are you addicted?

Two of the most common biological addictions are to wheat (gluten) and dairy products. You may think you don’t have to worry about them because you’re not allergic to either one. Truth is, you probably have no idea what effect they’re having on you. How many times have you gone three days without eating wheat or dairy protein? (Butter contains a negligible amount of protein.) Both gluten and dairy products have known inflammatory effects. (p. 48)

Fasting vs dieting

Here’s another example of the stark difference between dieting and fasting, based on an experiment I ran on myself. Ten years ago, while I was doing research for my 2014 book The Bulletproof Diet (the first big book that described ketosis with intermittent fasting), I decided to test my theory that the effects of fasting are more powerful than the effects of calorie consumption. I intentionally did everything wrong from the standpoint of the calorie-counting police. I ate a staggering 4,500 calories a day and kept doing it for a month, but for breakfast I had only Bulletproof Coffee with tons of butter to raise the number of calories in it. I cut my sleep to less than five hours a night, which triggers obesity. I stopped exercising. But I continued my program of intermittent fasting as I did all those things. By the straight, Ancel Keys–style accounting of the CICO diet, I should have gained about 20 pounds. I was hoping I’d gain only 3 pounds or so. That would have poked a big enough hole in CICO that I’d feel vindicated. The results were even more startling: I actually lost weight. I felt amazing. (p. 65)

CICO (Calories In, Calories Out) diets

The goal of diet culture is to make you feel as though a better you is just out of reach. That’s one of the many reasons why the “calories in, calories out” model, commonly abbreviated as CICO, should be relegated to the dustbin of failed science. This approach treats your body as though it’s a meat robot when in reality it’s a dynamic system that responds to calories differently based on their source, the time they’re consumed, and the unique physiological makeup of the person consuming them. Yet the myth lives on, leaving obesity, shame, and suffering in its wake. (p. 61)

 The "eat small meals" myth

A great many diet plans advise you to eat every three hours to keep your metabolism humming along at warp speed so you can lose weight. If you follow that advice, the minute you hit the three-hour mark and you start feeling the slightest bit hungry, you answer the ghrelin response and eat something. If you don’t, cravings kick in, your blood sugar level starts to drop, and you yell at someone nearby because you feel like crap. (You are feeling hypogly-bitchy!) Your biggest question at three hours isn’t whether to wait a few more hours before eating but what type of calories you’ll be putting in your body for your next meal. This is a bad idea because your body never gets a break, and the constantly high blood sugar level created by constant snacking ages you. (p. 68)

Fasting is primal

The history of human evolution is also the history of food. Believe it or not, it’s the history of fasting, too. Our bodies and brains are inherently adapted to it. (p. 81)

Fasting—either with no food or with a vanishingly few calories from plants—was simply a part of our ancestors’ lifestyles. They had no choice. This habit of eating and then fasting continued for not just decades or centuries or even a few millennia; humans have lived a lifestyle of feasting and fasting for almost 290,000 years. (p. 82)


The modern routine of breakfast, lunch, and dinner is less than two centuries old. (p. 85)

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. (p. 85)

The three types of fasting

Intermittent fasting 

The most workable intermittent fasting schedule for all but the most extreme is to skip breakfast, then eat lunch and dinner. It seems extravagant to call such a straightforward guideline a “biohack,” but that’s really what it is. Create an eating rhythm that supports your sleep rhythm and the circadian rhythm that underpins all of it. Don’t consume your nightly meal too late. The breakfast-skipping approach to fasting is very pragmatic. (p. 110)

The book repeats something I learned from Dr. Mercola's EMF*D...

Ideally, you should always leave at least three hours between your meal and the time you go to sleep. (p. 106)

It's actually a muscle-growth hack

Keep fasting just a few hours past the time when you wake up, and your body significantly reduces the secretion of insulin while it increases secretion of human growth hormone, or HGH. This is important, because HGH aids in cellular repair, encourages fat burning, and assists in the development of lean muscle mass. To maximize the benefits of this process, you should wait at least six hours after rising before you eat your first meal. (p. 105)

24-hour fast

OMAD is just a twenty-four-hour fast: you have a meal, and you don’t eat until you have a meal at the same time the next day. (p. 70)

OMAD is a cornerstone of my intermittent fasting regimen, and it should be for yours, too. You might be surprised, then, by what I’m going to tell you next: doing OMAD every day is a terrible idea. Fasting purists get their hackles up when they hear that, but after ten years of answering people’s questions about fasting on my blog, I’ve lost track of the number of people who feel great on OMAD-style intermittent fasting, vow to do it every day, and regret their decision two to four months later when they have to climb out of a health hole they dug for themselves. Intermittent means intermittent! If you do OMAD every day, expect to see your sex hormone levels fall (this applies to both men and women), your sleep quality drop, and your hair thin. (p. 71)

I'll add, OMAD is an especially good idea if you're of Northern or European extraction and live somewhere that you get four seasons, your ancestors for tens of thousands of years went without frequent feeding during cold winter months. The echoes of their deprivation reverberate through your genes as the cold fingers of winter caress the back of your neck and you'll benefit from seasonal signaling of scarcity to your biology.

36-hour fast

The thirty-six-hour fast is my favorite because it is vanishingly easy. I go to sleep (that’s eight hours of fasting), then have Bulletproof Coffee for breakfast so my energy is high and my blood sugar is low. Lunchtime rolls around, and I’m not hungry. I tell myself I might have dinner, which makes my body stop thinking about food. But at dinner, I tell myself, “Hey, skip dinner and sleep on it, and you’ll get another eight hours of fasting—that will be thirty-two hours!” When I wake up, I find that I don’t even want breakfast. I have no hunger at all. By the time I eat lunch, I really only had to skip one meal: dinner the night before. A thirty-six-hour fast without feeling denied or even very hungry is entirely possible. (pp. 72-73)

Perhaps you've tried multiday fasts before and found that you had a lot of trouble getting to sleep or woke up in the middle of the night anxious - Dave's solution: eat a very small amount of carbs (white rice or sweet potatoes) or honey before bed.

Switch things up

For maximum impact, I recommend regularly changing not only the duration of your fast but also the style. You might try a high-protein breakfast with plenty of fat on Monday, OMAD on Tuesday, intermittent fasting on Wednesday, OMAD on Thursday, intermittent fasting on Friday. On Saturday you eat whatever the heck you want, then on Sunday you circle back to OMAD. You are making your body stronger by cycling into and out of lipolysis and ketosis. (pp. 71-72)

An economic hack

If you've ever thought...

Biohacking is SO expensive! All these products, supplements, and organic food - how do you afford all this stuff?

Habituating just two types of fasting, intermittent daily fasting and once-a-week OMAD, cut the number of meals you eat a week nearly in half. This can free up a surprising amount of money (and time) that can be invested in high-quality, organic food, supplements, or, heck, Bitcoin (and then you'll be able to afford all the Biohacking luxuries your heart desires after the next halvening cycle).

Fasting is a Nootropic

When you skip eating for a whole twenty-four hours, your senses sharpen, and your focus increases. The less toxic material you have in your bloodstream and lymphatic system, the higher your ability to reason. This is because the tremendous amount of energy that your internal organs normally require for digestion is now being shunted to the brain. (p. 93)

Speaking of sleep

There is some evidence that sleeping on your left side can reduce pressure on the stomach, which is a good habit when you go to sleep on a full stomach. The rest of the time, sleeping on your right side is better for your heart. (p. 119)

Fun fact

If you want to impress your friends with an argument for drinking alcohol, here it is: alcohol causes a short-term increase in body temperature and raises your heat shock proteins. That’s why snow rescue dogs used to carry a little cask of brandy on their collars—so that hypothermic people could get a quick burst of heat from drinking it. (p. 122)

Fasting is a spirituality hack

The simple act of denying your body food can be a significantly more expansive spiritual act than meditation or solitude alone. If you use fasting to deepen your faith or expand your consciousness—or even if you just keep yourself open to these possibilities—you will achieve much better results than if you focus narrowly on goals of weight loss or longevity. When you approach fasting this way, there is also a wonderful humility to it. (p. 153)

Try holotropic breathing

In fact, I’ve seen more through holotropic breathing than I have through experiencing ayahuasca. You can have experiences like that, too. Some people practice it alone, but that’s not for the faint of heart. I recommend that you find an expert in holotropic breathing and try it when you are doing a spiritual, contemplative fast. You won’t be sorry. (p. 161)

Fasting is lucidifing...

Go for a walk in the forest when you are immersed in a fast, and observe the woods around you. Everything is a different color than you remember it being. The leaves on the trees are vibrantly green. Your senses are wide open. Most of the time we sit with our senses partially closed off, because we don’t need all of the information they have to offer. We already have more food than we need and more information—more distractions—than we need. When you do a spiritual fast and you spend some time in nature, the whole world’s a different place. (p. 164)

Sex and fasting

Good news...

expect an epic orgasm, because your brain will be powered by ketones and you will be in a slightly altered state. It’s just that you’ll regret it in the morning. If you’re a woman and you have sex during an extended fast, your orgasms will likely be more intense as well. You don’t read about it often, but both men and women can have intense spiritual visions during orgasm. Sex and fasting together make it far more likely. (p. 157)

Fasting and supplements

Many will question: Can I take supplements while fasting? Dave suggests that's generally okay although there are a few supplements you'd want to avoid: B vitamins, Multivitamins, fish oil, and iron or multimineral supplements.

What supplements might you want to take on fasting days?


Charcoal moleculeThis is the number one supplement I suggest taking during a fast, yet most people overlook it. It isn’t sexy, I guess.
It traps toxins and chemicals in your gut, preventing them from being absorbed into your bloodstream. Instead of these poisons becoming a part of whatever fat you’re carrying around, they leave your body as waste products.
Here’s one more really cool thing about activated charcoal: it will reduce the severity of your cravings during your fast. It’s startling: you get cravings, you take charcoal, and now you don’t feel hungry anymore.
Daily dose: 1 to 10 1,000 mg capsules, away from medications, fewer if you get constipated. (p. 180)

You can take most vitamins and medications that say “with food” with a Bulletproof Coffee because the fat helps absorption and you will still be fasting. Even a small amount of fat (1 teaspoon of C8 MCT oil plus 1 teaspoon of grass-fed butter) is often enough. (p. 194)

Take a “supplement fast”

Regardless of whether you’re fasting or not, there’s a case for occasionally mixing up or skipping what you take. It’s that you don’t want your body to get metabolically lazy by downregulating its own production of protective compounds; this is another example of how the body hates consistency. (p. 175)

Dave is no fan of BHB Ketone salts

I believe that taking ketone salts regularly is not a good idea. In the last interview he gave before he passed away, Richard “Bud” Veech, the world’s most experienced ketone researcher, who studied ketosis for more than four decades, told me that ketone salts cause mitochondrial harm. Are they safe for short-term use, as during a race? Almost certainly. Do you want to take them regularly? Probably not. (p. 138)

I've tried a BHB ketone supplement and... I loved it! It tasted amazing, assuaged my hunger some, and was energizing but I wouldn't take supplemental ketone salts often.

During fasting, I sip infoceuticals

Non-pharmacological, side-effect-free downloadable derivatives of supplements and medicines that take advantage of the phenomenon of water memory - which is imprinted on water via quantum collocation and electromagnetism using this device...

Infocueticals typically have 1/3 or half the effect of the actual medicine being imprinted. The uplifting effects on mindset and mood are even more noticeable while fasted. If you're skeptical of Infopathy that's understandable, it's a game-changing application of a little-known scientific phenomenon. But I'd urge you to evaluate the scientific evidence (presented in my biohacker review) that downloadable medicine is no longer science fiction...

For the fairer sex

The good news is that all available evidence suggests that women have just as much to gain from fasting as men do, especially when it comes to disease prevention. (p. 200)


On the other hand, even without fasting, unending ketosis suppresses menstruation! It is not an appropriate diet for women over long periods of time unless you cycle into and out of it on a regular basis, at which point it is fantastic. (p. 202)

This is hugely important: NEVER FAST WHEN YOU ARE PREGNANT! (p. 207)

Don't let fasting stress you

Remember that fasting can cause more than just physical stress. This is true of all types of fasting, but especially of OMAD because it is the longest fast you can do in one day. Restricting yourself to one meal a day can be taxing to your mind if you obsess over food all day. Take care of your stress levels by practicing yoga, meditating, exercising—really, whatever helps you find your Zen. (p. 221)

Point taken, when fasting stack other stress management hacks; meditation is great and will often relieve food cravings.

Dopamine fasting

The purpose of a dopamine fast is to abstain from anything that causes your body to secrete dopamine, a neurotransmitter that is closely associated with our pleasure sensors and can play a role in reinforcing addictions. Eating spicy or sweet food causes a dopamine spike. So does having lots of social interaction, in person or on social media. Just about all of life’s pleasures give you a dopamine hit: gaming, watching TV or pornography, gambling, shopping, and having sex. Oh, and drugs and alcohol. The intent of a dopamine fast isn’t to make yourself miserable, it’s to allow your dopamine receptors to take a break so that when they come back online, they’ll become more sensitive to dopamine. When you stop the fast, which normally lasts two to seven days, you will find that everything you do feels more pleasurable. (p. 225)

Dopamine fasting is a great idea for biohackers who use Modafinil often, which can desensitize dopamine receptors.

Cool fact

According to one famous estimate from Oak Ridge National Laboratory, 98 percent of the atoms in your body are replaced every year.1 Almost all of your cells are replaced every seven years. Matter moves through you, energy moves through you, yet somehow you remain you—ideally, a steadily improving version of you, but you all the same. (p. 213)

The book is surprisingly philosophical at points...

Are you going to let [fear] run you, as if you were still standing defenseless on the savanna in front of a hungry tiger? If so, as Seneca says, there will be no limit to your miseries. Find the thing that is the most important to you, the thing that is the most scary, the thing you honestly believe you could never go without for any length of time. Then fast from that. Go without, even if for just one day. Just long enough to make you uncomfortable. Then look in the mirror and see if you like the person who’s there. I promise you that you’ll like that person better than you did before. That is the magic of fasting. (pp. 241-242)

5 stars

The book gets 5-stars from me. It captures the state-of-the-art science on the ancient practice of fasting, is packed with pragmatic takeaways, and the story-telling is compelling. I put it down wondering where I could do a 4-day spiritual fast in a cave, like Dave!


Break the rules, not the fast with world-renowned biohacker and Bulletproof Coffee founder Dave Asprey, author of The Bulletproof Diet, Head Strong, and other New York Times bestsellers.

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