You may be convinced training in a fasted state will cause your muscles to shrink, shrivel and die. I think the supplement industry has some blame—they’ve convinced naïve trainees they need pre, post, and intra workout supplements.
We’ll get into some research later, but let me first share some less-than-scientific examples that are related to this topic—non-scientific in the sense that I’m sharing my experiences and general observations (not research).
Ketogenic Dieting and Glycogen Depletion: Some of my regular readers know I’ve used lowcarb/ketogenic dieting for fat loss. The goal of such diets is to go into ketosis, a state in which you are primarily using fat for fuel. In order to achieve ketosis you must first significantly reduce the glycogen stores in your muscles and liver (if you aren’t familiar with the term, glycogen refers to glucose that has been transported to the muscles/liver to be used as needed).
Glygocen depletion doesn’t happen in one workout or even one day. It usually took me a few days/workouts. Here’s my observation: the idea that your muscles are “starving” after a few sets of weight training is ridiculous. We’d be extinct as a species if our bodies were that inefficient and incapable of performing rigorous activity without a “feeding.”
Granted, there’s nothing wrong with using post-workout strategies to quickly replenish glycogen (especially for hardgainers who are focused on building mass), but I believe the importance of this has been over-analyzed and over-stated. Read my post workout article and you’ll see why I think using only “fast absorbing” protein sources may not be the best idea, but let’s get back to the subject at hand (and my next observation).
Sumo Wrestlers: The world’s largest athletes regularly use fasted training in their daily regimen. They train in the morning on an empty stomach and work up a ravenous appetite. Their diet is usually consists primarily of two gigantic meals, each one having around 10,000 calories. Here’s my observation: the primary concern most have with fasted training is catabolism (muscle loss). Losing mass doesn’t seem to be an issue with sumo wrestlers. In other words, it seems the body is perfectly capable of compensating for any catabolism issues.
Having said all this, I was initially reluctant to train in a fasted state—I was still a little brainwashed by the before-mentioned supplement industry.
But some of the research in Eat Stop Eat set my mind at ease. Brad Pilon analyzed multiple studies and concluded, “fasting does not negatively affect anaerobic short-burst exercise such as lifting weights, nor does it have a negative effect on typical ‘cardio’ training” (Page 35). He goes on to establish the positive effects of fasted training, such as increased fat burning. You can read my Eat Stop Eat Review for more information, but I’d highly recommend this as a resource.
Another groundbreaking study came out about a year ago. 28 young, healthy male subjects were given a diet with half of their calories coming from fat and 30% more overall calories than they normally consumed—a recipe for poor health. The subjects were split into three groups: one group didn’t exercise; one group trained intensely 4x a week after a carbohydrate rich breakfast (and drank energy drinks during training); and one group did the exact same training routine in a fasted state (in the morning before breakfast).
Just as we’d expect, the sedentary group gained weight (an average of six pounds) and experienced a measurable decline in health (they began to develop insulin resistance, etc). The “fed training” group gained about half as much weight as their sedentary counterparts and also began to develop the same health problems.
Remarkably, the fasted training group gained virtually no weight and showed no signs of insulin resistance. The researchers came to the following conclusion:
This study for the first time shows that fasted training is more potent than fed training to facilitate adaptations in muscle and to improve whole-body glucose tolerance and insulin sensitivity during hyper-caloric fat-rich diet.1
So it seems there are some hormonal advantages to fasted training. But I want to restate something I’ve said before: no training will overcome a crappy diet. The exercising subjects in this study underwent a vigorous cycling and running routine four times a week. But their diet was horrible, so the “best” outcome was no weight gain—not weight loss. In other words, no form of training will help if you aren’t achieving a negative calorie balance.
Fasted Training and Stubborn Fat
I think the most exciting aspect of fasted training is the possibility of targeting “stubborn” fat deposits (lower abdomen and lower back for men, hip and thigh for women). It can happen in two ways:
1. Hormonal: something else I learned in Eat Stop Eat (and elsewhere) is that fasting increases the level of certain hormones: “Epinephrine and Norepinephrine are both fight or flight hormones, often called adrenalin and noradrenalin or collectively ‘catecholamines’” (Eat Stop Eat, page 72). Both fasting and intense exercise are known to increase catecholamines, and these hormones seem particularly helpful for oxidizing fat—especially stubborn fat.
2. Yohimbine HCL: I’ve written about yohimbine before, but I’ll re-state it in a summarized form. Stubborn fat deposits tend to have a significantly higher number of alpha 2 receptor sites (compared with “non-stubborn” areas). These sites basically “tell” the fat cells not to release their contents (lipids). Yohimbine supplementation, if done properly, can temporarily “disable” alpha 2 receptor sites. But yohimbine must be taken in a fasted state (or a state of low blood glucose) to be effective–insulin competes for these same receptor sites, rendering the supplement useless (the proper dose is .2mg/kg example: 20mg for a 220lb person 0.09 mg/lb of body weight).2
As a side note, I’ve also notice that supplementing 2-3 grams of L-Tyrosine pre-workout in a fasted state seems to be more effective than a fed state.
But keep something in mind: this strategy also only works with an overall negative calorie balance. Otherwise the fatty acids released during training can get re-deposited (possibly right back to those stubborn areas).
The BCAA Debate
Conventional wisdom is that catabolism can be avoided by supplementing 10 grams of Branch Chain Amino Acids before and after you train. But I’ve also seen arguments against taking anything before you train. It goes something like this:
1. BCAA’s cause an insulin response, which may partially interfere with the before-mentioned benefits of fasted training.
2. The amount of protein oxidized during training is minimal and can easily be replaced after you train (with no harm to muscle strength/size).
Where does this leave us? I think it’s a matter of individual preferences and priorities, and I doubt it makes that much difference if your overall nutrition is in order. My theory is the leaner you are the more important BCAA supplementation would be. But this is a miniscule in the grand scheme of things.
Here’s another suggestion you may want to consider–do some light cardiovascular training first thing in the morning on an empty stomach. Have a cup of coffee then do about thirty minutes of brisk walking or riding a bike a few times a week.
I believe fasted training is a viable option for those who want to lose fat. It must be part of an overall strategy involving a negative calorie balance. It may be especially helpful for trainees who are already fairly lean and trying to target stubborn fat deposits.
Check out my article on intermittent fasting if you want a comparison of different programs that incorporate the fasted training strategy.
1. J Physiol. 2010 Nov 1;588(Pt 21):4289-302. Training in the fasted state improves glucose tolerance during fat-rich diet.
2. See also: Yombine HCL