What You Should Know About Intermittent Fasting

In fitness circles, the concept of intermittent fasting (IF) is catching like wildfire, and it’s no surprise as to why. There is some intriguing new published research showing that IF may offer a host of health and body composition benefits. Additionally, a small but growing group of IF experimenters are swearing by these relatively new fat-loss techniques, techniques that include skipping meals and sometimes going entire days without eating!

I know, I know…the idea of fasting for a few extra hours every day seems to fly in the face of conventional nutrition wisdom, and many of you probably think that going entire days without eating is sheer lunacy–I get it. As a long-time proponent of grazing (eating smaller meals more frequently), I was a little skeptical of the concept too. Would I get moody? Experience blood sugar drop? Have muscle proteins dissolve and burned for energy? It’s enough to make any weightlifter run screaming from the room.

But here’s the funny thing. If you do intermittent fasting right, none of that actually happens.

How do I know? Well, first, there’s the research. In fasting-related studies, muscle isn’t lost like you’d expect, unless there’s a huge energy deficit and there’s no weight training involved. However, I’ll be honest…I don’t always believe the research. Even though I spent eleven years in higher education and earned a research-based PhD, I know how poorly research can be conducted. Furthermore, how many actual bodybuilders end up in research studies? Very few.

My Experiments with Intermittent Fasting

I do have some additional evidence, however: I myself have spent the last eight months experimenting with intermittent fasting. Indeed, I turned myself into a human guinea pig and tested dozens of different fasting-related protocols. Throughout the process, I meticulously recorded everything from body composition to blood values to lifestyle factors, all in an attempt to figure out whether intermittent fasting is a new and potentially valuable paradigm shift in the nutrition world or just another fad diet.

(For those who are interested, I published my findings in a free E-book called “Experiments with Intermittent Fasting,” which you can download here.)

In the end, some of the experiments were a huge success, leading to improvements in my body composition, health, and performance. Others were disastrous, causing me to drop muscle mass and develop food obsessions. Yet at the end of the day, I was able to accomplish most of my goals. I lost about 20 pounds of fat while preserving most of my lean mass, strength, and power. According to my Intelametrix device (a validated ultrasound-based form of body composition testing), I went from a fairly lean 10% body fat to a very lean 4%.

Here are some progress photos:



Of course, not everyone is interested in getting leaner. So what about muscle gain?

Well, another one of my clients (a guy with different goals than me) gained 20 pounds of quality weight in the last few months while also experimenting with intermittent fasting. He also improved his aerobic and anaerobic exercise performance at the same time. His protocols were obviously different than mine, but his results also show that intermittent fasting can assist with either fat loss or muscle gain as long the protocols are a good fit are and are followed correctly.

Different Fasting Styles
For those of you who don’t even know what I’m talking about here, quite simply, intermittent fasting is not eating for a short while, and although I know that some of you bodybuilders are afraid of that very thing, the truth is that you already do intermittent fasting.

That’s right; every night, from the time you eat your dinner to the time you eat your breakfast, you’re fasting, and believe it or not, that fasting brings some unique benefits. So before you freak out and summarily dismiss the concept, understand that you’re naturally already doing some form of IF.

Of course, the type of intermittent fasting I’m talking about here extends out a little longer than overnight. The most extreme version is one in which you simply eat every other day, fasting on the days in between. It’s called alternate day fasting, and this one’s probably not for people who train regularly and want to be strong, muscular, and lean.

There are other versions, of course. The most flexible option simply recommends a single day of fasting as little as once per month or as often as once per week. This is the type of fasting the client I referred to above followed. He cycled his calories during the week, eating high calories and carbs on strength training days and moderate calories and carbs on conditioning days. Then, every Sunday, he followed one of my full-day fasting protocols. These include avoiding food for 24 hours but drinking lots of water and green tea and supplementing with 5g BCAA, 3g fish oil, and ½ serving of a green food product like greens+ every few hours.

Another interesting version doesn’t involve whole days of fasting. Rather, it extends the daily fast from the typical 10-12 hours to a longer 16-20 hours. You would also train at the end of this fast using 10-15g of BCAA during your workout, and then you’d eat all your calories during a 4-8 hour post-workout window. I extensively tested this form of fasting personally and found that it can be very physique- and performance-friendly. However, you have to do it right; if you don’t, then trouble awaits.

The Benefits of Intermittent Fasting
Many of you are probably wondering why I did these fasting experiments in the first place.
Well, a lot of it is curiosity…I’m what you’d call a ‘professional dieter’. In other words, I’ve tried nearly every diet or nutritional protocol that’s around in order to test its efficacy.

In addition, I’ve been pursuing a new goal: track and field. When you’re running competitively, every pound has got to earn its rent, so I wanted to test drive this new way to drop fat and get extremely lean while staying strong and powerful. Finally, the proposed benefits of IF are quite interesting and extensive. They include:

• blood lipids (including decreased triglycerides and LDL cholesterol)
• blood pressure (perhaps through changes in sympathetic/parasympathetic activity)
• markers of inflammation (including CRP, IL-6, TNF, BDNF, and more)
• oxidative stress (using markers of protein, lipid, and DNA damage)
• risk of cancer (through a host of proposed mechanisms; we’ll save them for another review)

• cellular turnover and repair (called autophagocytosis)
• fat burning (increase in fatty acid oxidation later in the fast)
• growth hormone release later in the fast (hormonally mediated)
• metabolic rate later in the fast (stimulated by epinephrine and norepinephrine release)

• appetite control (perhaps through changes in PPY and ghrelin)
• blood sugar control (by lowering blood glucose and increasing insulin sensitivity)
• cardiovascular function (by offering protection against ischemic injury to the heart)
• effectiveness of chemotherapy (by allowing for higher doses more frequently)
• neurogenesis and neuronal plasticity (by offering protection against neurotoxins)

To be frank, most of the research to date has been done in animal models with pretty limited data collection in humans. While the human studies that have been done show some promise, we’re probably a good 5-7 years away from knowing exactly what IF does in humans and why, and 10-12 years from knowing which IF protocols are “best.” That’s another reason why I’ve been putting IF to the test.

Frequent Meals and Intermittent Fasting
Of course, people have been getting in shape for a very long time without using the intermittent fasting ideas I outline above. In fact, the dominant nutrition paradigm suggests that we should be eating smaller meals every few hours…so doesn’t intermittent fasting just fly in the face of everything we’ve been told to do?

Not really. The rules of good nutrition haven’t changed. You still need to eat good foods. Calorie balance still applies. Peri-workout nutrition is still important. The only real difference between more traditional bodybuilding-style eating and intermittent-fasting style eating is how you distribute your calories between days or meals.

This means that for most people, as long as we eat the right foods in the right amounts, meal frequency is a matter of personal preference. You can eat lots of small meals (every few hours) or you can eat a few big meals (with bigger time gaps between them). You can even go an entire day without eating, once in a while.

But what about speeding up the metabolism, controlling appetite, and controlling blood sugar?
New data have been published showing that eating more frequently doesn’t necessarily speed up the metabolism, and although grazing is supposed to enable better appetite and blood sugar control, that effect isn’t reliable. For some people, eating more frequently does help to control both. For other people, the opposite is true; eating less frequently gives them an appetite and blood sugar advantage. This means that your decision to eat small meals more frequently or larger meals less frequently should be based on what works best for your schedule, your mood, your appetite, and how you prefer to spend your time, and that flexibility is pretty cool.

In the end, we shouldn’t totally abandon the grazing concept. Instead, we should recognize that we don’t have to graze. It’s not a must; rather, in most cases, it’s a choice.

A growing number of experts claim that short fasts can accelerate fat loss and make you healthier. As a result, I spent the last eight months testing the most popular Intermittent Fasting (IF) protocols for myself. During this time, I dropped twenty pounds of weight (from 190 pounds to 170 pounds) and reduced my body fat from 10% to 4% while maintaining most of my lean muscle mass. I also helped others lose fat and gain muscle using a host of different intermittent fasting strategies.

Of course, the full details of my experiments are beyond the scope of this article. However, if you’d like to learn more, you can check out my free e-book called “Experiments with Intermittent Fasting.” In the book I cover everything I did, including details of my training programs and my exact eating plans for all of the IF protocols I tried. There’s also measurement data (including blood work) and a host of other cool features you won’t want to miss. The best part? It’s 100% hosted online so anyone interested in more can pop over to the site and read the entire thing right now, for free, without having to enter an email address or anything.

As a result of my experiments, I learned that IF is 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. Simply put, when people control their calories, eat good quality food and train regularly, they get in shape. The rest is a matter of personal preference, lifestyle, and individual difference.

About The Author

John Berardi received his PhD in Exercise Physiology and Nutrient Biochemistry at the University of Western Ontario, Canada. He’s currently an Adjunct Professor at Eastern Michigan University and the University of Texas.

As an elite nutrition coach and exercise physiologist, Dr. Berardi has coached hundreds of elite amateur and professional athletes. In fact, in the last two Winter Olympics alone, his athletes collected over 25 medals, 12 of them gold. He’s also a high performance consultant with Nike.

Further, for the last four years, Dr. Berardi has acted as the director of the world’s largest body transformation project. This one-of-a-kind fat-loss coaching program has produced more total weight loss than all eleven seasons of The Biggest Loser combined.