All About Intermittent Fasting, in Under 10 Minutes

A growing number of experts claim short fasts can accelerate fat loss and make you healthier. So we spent 6 months testing the most popular Intermittent Fasting (IF) protocols ourselves. Find out what IF is, whether you should do it, and if so — how.

For years, Dr. John Berardi, Chief Science Officer of Precision Nutrition, has advocated frequent meals, spaced 3-4 hours apart, consisting of nutrient-dense, healthy food. That strategy — when combined with a smart exercise program and world-class coaching — has helped thousands of our clients drop over 120,000 pounds of fat in the last ten years.

Proponents of IF, on the other hand, eschew the idea of eating so frequently. Many claim to have achieved quicker fat loss and better health by deliberately skipping meals and sometimes going entire days without eating.

The IF research is still in its infancy — indeed, it may be 5-10 years before it reaches critical mass and becomes a mainstream nutritional idea — but in certain quarters, the benefits of intermittent fasting have reached almost mythical proportions.

With research lagging behind at a snail's pace, but enough anecdotal evidence to go off of, we decided to do what we do here at Precision Nutrition: test it ourselves. Here's what Dr. Berardi found, in his own words.

Why Experiment With Intermittent Fasting?

I'm a professional dieter. In other words, I've done nearly every diet or nutritional protocol that's around to test its efficacy. Intermittent fasting has a very small, yet strong, following and enough research to pique my curiosity. I wanted to test it myself to see what kinds of physiological and psychological changes would come from it. Also, as a competitive, masters-level track athlete and life-long fitness enthusiast, I wanted to test a new way to drop fat and get extremely lean, while staying strong and powerful.

What Did You Test?

Since there isn't one definitive intermittent fasting protocol, I decided to test six different methods over the course of six months. I kept meticulous notes on everything from scale weight, body-fat percentage, and blood/hormonal markers, to lifestyle markers like energy levels, cognitive thought, and pain-in-the-ass factors.

What Happened?

Over the course of six months, I dropped twenty pounds of weight, from 190 pounds to 170 pounds. I also reduced my body fat from 10% to 4% while maintaining most of my lean muscle mass. Finally, I found two intermittent fasting strategies that I could follow indefinitely with no problem. Simply, I accomplished the goals I set for myself in a way that was easier and less time-consuming than “traditional” dieting.

What Are The Big “Takeaways”?

I think there are four main takeaways that readers of this book should come away with.

Trial fasting is a great way to practice managing hunger. This is an essential skill for anyone who wants to get in shape and stay healthy and fit.
More regular fasting isn't objectively better for losing body fat. While my IF experiments worked quite well, the intermittent fasting approach (bigger meals, less frequently) didn't produce better fat loss than a more conventional diet approach (smaller meals, more frequently) might have.
More regular fasting did make it easier to maintain a lower body fat percentage. Intermittent fasting isn't easy. However, I did find that using this approach made it easier for me to maintain a low body weight and a very low body fat percentage vs. more conventional diets.
Intermittent fasting can work but it's not for everyone, nor does it need to be. In the end, IF is just one approach, among many effective ones, for improving health, performance, and body composition.

So Intermittent Fasting Is Good, But Not Necessary?

Exactly. Intermittent fasting can be helpful for in-shape people who want to really get lean without following conventional bodybuilding diets, or for anyone who needs to learn the difference between body hunger and mental hunger. (And for the latter, I only recommend the Trial Fast.) It's a helpful tool and one I'll continue to use periodically. But it's not the end-all, be-all of nutrition or fitness. People have been getting in awesome shape — and staying in awesome shape — for decades without the use of intermittent fasting.

How Are IF and "Grazing" Similar?

Successful nutrition plans, whether they use smaller, more frequent meals or larger, less frequent meals all share a few commonalities. These include:

Controlling calories. When calories are controlled, progress is made. Whether you control them by eating frequent small meals or infrequent larger meals is up to you.
Focusing on food quality. Fresh, unprocessed, nutrient-dense food is a must, regardless of which eating style you adopt.
Regular exercise. Exercise is a critical part of the equation.

Once those three have been taken care of, it's a matter of personal preference and lifestyle considerations.

I'd Like To Learn More. What's Next?

Have 10 minutes? Read Appendix A. It's a cheat sheet that shows you exactly how to do intermittent fasting, including specifics on our three favorite protocols.

Have 30 minutes? Read about the individual fasts in Chapters 45 and 6. Then read the cheat sheet in Appendix A. Then check out Appendix B for some tips and tricks we learned along the way.

Have an hour or two? Read the entire Experiments with Intermittent Fasting book. We spent a lot of time researching, conducting the experiments, and writing. We'd love to share it with you and hear your thoughts.

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At Precision Nutrition we pride ourselves in finding the fastest and easiest nutritional strategies to help real people lose fat, get healthy, and enjoy life-long fitness.

In our experience, the best way to find those strategies is to put them to the test ourselves. And once we collect our data, we pass the information along to you so you can use it to help make your life better.

If you'd like to stay connected and be the first to know when these experiments happen, feel free to join our newsletter list below.

And if you'd like to learn more about our intermittent fasting experiments, feel free to move on to the next chapter by clicking the title of the next chapter below.