Introduction

Hi, My Name is John. And I Haven't Eaten in 24 Hours.

I haven’t eaten anything in 24 hours. Am I starving? Craving something to eat? Well, no, not really. I’m just mildly hungry.

It’s weird. You know that hunger feeling you get about 4-5 hours after your last meal? Where your stomach’s reminding you that it’s been a while? I’m not even that hungry.

I’ve learned that hunger peaks at that point and immediately diminishes. After a while, even if you haven’t eaten, you get less hungry.

About 20-24 hours later, hunger comes back again. But never as bad.

There’s a good scientific reason for this hunger wave, although my hunger wave is probably different than yours. The explanation has to do with hormones like epinephrine, norepinephrine, insulin, glucagon, leptin, and ghrelin, and how our organs respond to these hormones. But this isn’t a biochemistry text. Let’s skip the heavy science.

If you’re a fitness-conscious person – whether you graze on small meals throughout the day or eat three squares like clockwork – the thought of fasting for an entire day might scare the hell out of you.

Most active people start to freak out about 4-5 hours after their last meal.

“Somebody sound the alarms! If I don’t eat soon, I’m gonna…”

You’re gonna… what? Explode? Die of starvation? Shrivel up and lose all your muscle mass?

Actually, none of these happen. In fact, you might even lose a little body fat.

New research suggests that a short, periodic fast might actually rev up your fat-burning machinery while helping you control glucose and insulin. Important hormonal changes mean that fasting might even help your muscles grow when the next exercise session (and meal) comes. You might lose more fat and gain more muscle, all by skipping a few meals.

But even if you don’t lose extra fat by fasting, I promise you will lose something important: that ridiculous, unarticulated fear of not eating every few hours. And damn it, that’s liberating.

(Don’t worry, you can still eat every few hours – most of the time – if that’s what works best for you.)

And even if you don’t gain any extra muscle, you’ll gain something more important: perspective. I know I did. You see, I’ve been experimenting with various fasting ideas for the last 6-months.

The one-day fasting experience

It started as a one-off assignment, part of a fat loss coaching program Precision Nutrition offers called the Lean Eating coaching program.

Each year, we work with nearly 3,000 men and women. We provide them with workout programs, nutrition habits, daily lessons, and assignments, all designed to help them achieve the best fat loss results of their lives.

The program works. To date, more weight has been lost in the Lean Eating program than in all 11 seasons of The Biggest Loser combined. Lean Eaters have gained lean muscle mass, shed thousands of pounds of fat, enhanced their health profiles, and improved their lives.

Anyway, one of our Lean Eating assignments is to go a full 24 hours without eating. It’s scary, and it makes people uncomfortable… which is exactly why we do it.

It’s not just a random “don’t eat” instruction. There’s a specific plan. Assuming you’re going to fast on a Sunday (and assuming you’d like to try it), here’s what to do:

10 PM Saturday:

  • Eat your last meal of the day
  • Drink 500 mL (2 cups) of water

10 AM Sunday:

  • Drink 1 L (4 cups) of water + 1 serving greens powder
  • Drink 250 mL (1 cup) of green tea
  • Take 5 grams BCAA (branched chain amino acids) powder (or take 5 capsules)

3 PM Sunday:

  • Drink 1 L (4 cups) of water + 1 serving greens powder
  • Drink 250 mL (1 cup) green tea
  • Take 5 grams BCAA (branched chain amino acids) powder (or take 5 capsules)

10 PM Sunday:

  • Eat a small snack before bed
  • Drink 500 mL (2 cups) of water

Monday:

  • Eat normally

What to look out for

If you’d like to try this, be aware that you’ll be hungrier than usual when you start eating again Sunday night and Monday. Plus, it’s easy to play little games like “rewarding” yourself for having such a low calorie day on Sunday. This combination means it’s easy to overeat – either leading up to the fast or after the fast – if you’re not paying attention. So pay attention.

On the other hand, if you’re a diet junkie, you might think, “If Dr. Berardi says one day of fasting is good, five must be awesome!” Don’t do that either. Remember, this fast is short, it’s intermittent, and – in this case – it’s a one-time thing.

In other words: Eat normally for the week. On one day, don’t eat for a little while. That’s all.

What’s the point of this exercise? Why “starve” yourself for a day? Here’s what people learn when they do our fasting assignment for the first time:

Hunger is not an emergency

Many people think hunger is an emergency and panic when it kicks in. But hunger is just a feeling. Commit an entire day to fasting, and you’ll realize that hunger really isn’t something to panic over. Nothing really bad happens if you miss a meal or two. After all, our prehistoric ancestors didn’t have a Taco Bell on every corner. We evolved to deal well with hunger. Allow yourself to get hungry. Then sit with the feeling rather than trying to make it go away immediately.

Physical vs. psychological hunger

Often when people think they’re hungry, they’re not experiencing true physiological (body) hunger, but rather psychological (head) hunger. The better you know the difference between the two, the better you understand your body’s signals. By the end of the day, you’ll feel real body hunger. In the future, use that feeling as a reference point to interpret your appetite correctly.

Eating as a privilege

I’m the Director for a non-profit called The Healthy Food Bank. We raise funds and food for food banks throughout North America. Most of that goes to families who are “food-insecure.” They’re not people sleeping on sewer grates. They’re people who are barely scraping by. They have food, just not enough to feed their kids every meal, every day. Taking a day to fast reminds us that there are people out there who fast regularly - not voluntarily - but because they don’t have food. We’re reminded that eating is a privilege.

Eating as a responsibility

Eating is also a responsibility. When we cram our bodies full of fast, processed, low-quality food, we’re not taking that responsibility very seriously. A day without food resets our perspective. We can remember to not take eating for granted.

Food marketing

Food advertising and marketing often flies under our radar when we’re fed. But that’s exactly what makes it so effective: It works on our subconscious. When fasting, everything changes. Food marketing jumps out at us. We’re aware of the manipulation. With awareness comes power. No more mindless junk food runs prompted by billboards or radio commercials. Now you’re in control.

As you can see, there are many benefits to a single day, trial fast; most of which are psychological. But we’re only scratching the surface here. There are physiological ones, too.

The cool part? You don’t have to be an “intermittent faster” or follow some wacky diet plan to experience these benefits. All you have to do is not eat for one day. Then you can get back to normal… although I suspect your “normal” will be a little different afterward.

My “normal” has changed dramatically since my first Lean Eating-inspired fasting experiment.

In fact, over the last year I’ve put at least half a dozen different fasting protocols to the test, recording everything along the way. Nearly every week, I’ve tried some fasting-related strategy and recorded the results.

This book explores that journey.

Now, if you’re expecting a master’s level dissertation on the science of fasting intermittently, you won’t find it here. Although I’m a scientist by training, I only briefly touch on the research behind IF in this book.

You see, this project isn’t about an idea or a concept. And it’s certainly not about isolated laboratory research. Instead, this project is about putting ideas to the test in real life, in my life, through something I highly value: self-experimentation.

This is where theory meets empty-stomach reality.