One topic I seem to be asked about all the time is intermittent fasting (IF)—and it’s pretty obvious why this happens. If your life is busy, it’s easy to just not eat all day, then blast through a few thousand calories before going to bed. I’m pretty busy, so when this notion appealed to me a few years ago—and I wanted to save time and preserve my body composition—I gave it a shot. The verdict? Good idea, poor execution. IF does cause weight loss—at least this particular protocol does—but the problem comes when you think about what kind of tissue the lost weight actually comes from.

Are you really burning fat? Are you really building muscle? I found out the hard way.


When I triedFL04118_2013-1wtmrk IF, I’d been training one or two days per week because of time constraints. I used carb back-loading adjusted to my training schedule to maintain my weight and strength. At 220 pounds, I had 6% body fat as tested by a water tank—a level that most of my noncompeting clients hold comfortably year-round with carb back-loading (with an application of Carb Nite to get there). I’d wake up, have coffee, then run through the rest of the day without food—and, for the most part, without hunger. At about 7 p.m., I re-fed like nobody’s business. For the first week, my workouts felt great, my skin tightened slightly, and no aspect of the diet was a challenge. Six weeks in, however, it was time to stop. Despite being easy and convenient, my body wasn’t coping well to IF’s demands. People told me I looked “small.” Not bad, mind you— just small. I lost 18 pounds, but I was neither ripped nor shredded. Instead, I was flat, and my skin felt loose. My abs disappeared, I felt like crap, and my strength decreased with each workout after the first week. I’d clearly lost lean mass during my IF trial.


Why, I wondered, didn’t IF preserve my lean muscle mass as promised, despite the supposed massive increase in GH we’re always hearing about from IF proponents?

Well, being muscular and defined is a war between breakdown and synthesis. Being jacked depends on shifting all your forces toward growth and defending against destruction. As it turns out, IF does the exact opposite of what we need by shutting down synthesis and letting catabolic processes run wild.

Simply put, your body is not kind to your muscle mass while you’re fasting. Fasting rapidly adjusts several regulators of growth—many of which act to shut down the all-important mTOR pathway, one of the most critical pathways for protein synthesis and protection against protein breakdown. This cascade of suppression signals starts quickly, typically within 12 hours of fasting. Inhibiting the mTOR pathway prevents resistance training from triggering muscle growth when mTOR is deactivated. Not only can you not build muscle, but the same changes that prevent the activation of mTOR also prevent insulin from stopping the breakdown of muscle.


Although GH concentrations increase with IF, free IGF-1 levels decrease. This means that although GH goes up, only its fat-burning properties persist. Its muscle-building properties disappear. This decrease in free IGF-1 suppresses the mTOR pathway even further. It’s confusing, but by practicing IF, you’ll get greater GH release, but ablated anabolic response. mTOR activation protects against the destructive effects of cortisol. Shutting down mTOR allows glucocorticoids— catabolic steroids—to chew up muscle tissue.

Click NEXT PAGE to see the science behind Intermittent Fasting!


After weeks of digging through research, all I found to test the power of IF was a single study done on humans. One study, that’s all. It describes the results of an every-other-day fasting schedule on body composition. Two things came out of this study.

  1. Over the long term, there was no difference in total lipid, protein, or carb utilization compared with a standard diet.
  2. The study showed that IF decreases metabolism over time.

Other studiesFL04120_2013 done on Ramadan fasting—even ones that control and match calories intact between experimental groups—demonstrate the same result: For fasts of 14–36 hours, there’s no benefit. Only cost.

These results explain what happened to me and why I was unable to maintain my physique and my performance. If you’re starting with a high level of body fat, this can mask muscle loss and help you maintain strength for a while. But if you’re looking for more, you won’t be happy with anticatabolic protocols that allow catabolic reactions to run rampant. For the reasons outlined thus far, it makes each training session severely catabolic.


One thing that’s always overlooked with regard to IF is the fact that the body responds to both nutrient restriction and carbohydrate restriction, taking different actions with the two. Your body is highly sensitive to nutrient availability and energy balance. Take away energy (read: food) or overtax the system, and two things happen: Anabolic processes shut down, and catabolic processes start up.

Take carbs out of the diet and reintroduce them at the correct time, and you get all of the benefits of IF. In contrast, if you take all food out of your diet and re-feed, you’re suddenly adding in a batch of anti-anabolic, catabolic effects. Carbs are the drug here, not simply food.


My training hasn’t changed much, but I re-embraced the magic of carb backloading, gained weight, and got my abs back thanks to a crazy new supplement known as food.

Your first fast-breaking nutrition should prolong fat burning, and trigger muscle growth and repair. It doesn’t need to be much, but it needs to be something—a shake, perhaps. Don’t completely fast longer than 12 hours, ever. If you stop eating two hours before bed, then sleep eight hours, your first meal should occur within two or three hours of waking. This way, you’ll get all the purported benefits of IF—with none of the catabolic downside that comes with sticking to it religiously. FLEX