Fasting Does Not Negatively Affect Muscle Gain

Scientists studied the effects of weight training while fasting by observing Muslim bodybuilders during Ramadan. It turns out not eating after your workout might not matter.

With the increasing popularity of intermittent fasting, many people on both sides of the fence wonder how it will affect muscle gain. Conventional wisdom has trainees avoid a catabolic state like the plague, like the common belief that if you wait too long to eat after training you’re automatically destroying your hard-earned muscle. Some people still seem to be clinging to these concepts of the past, too worried that not being in a constantly hyperinsulinemic state is ruining their progress.

Now that might be a bit of biased journalism there, and I’ll concede that the potential for fasting to be a hindrance to training is a reasonable concern. If we simply extend out the idea of fasting ad absurdum, you will find that it not only prevents muscle gain, but it will eventually kill you when you cross from fasting to starving. But we need to ask where the cutoff is, since intermittent fasting has many other positive benefits that make it worth consideration, even for serious athletes looking for real results. A recent study in the International Society of Sports Nutrition answered that very question.

In the study the researchers found a pretty clever way to examine the anabolic response to fasting. They looked at the Muslim population during the time of Ramadan. Ramadan is a holy month in which participants do not eat or drink during the day, from dawn until sunset. However, there are still many Muslim athletes, and even some studies on the effects of Ramadan on soccer and other sports, but not for weight training.

The participants of the study were Muslim bodybuilders, but the results should apply to anyone looking to gain lean mass or strength. They weren’t elite level bodybuilders, but rather they recreationally performed bodybuilding routines at least three days per week. The group of participants was split into two – those who exercised during the day while fasting and those who exercised at night after having eaten.

Interestingly, as the fasting began, the total volume of exercise and the total caloric intake for the bodybuilders didn’t really change. They seemingly ate larger meals in the evening to compensate, and so their protein, fat, and carb levels were still roughly the same each day. The only major differences once fasting began were an improvement in body fat usage and some dehydration. For those Muslims participating in Ramada, drinking a lot of water after sunset is ideal to help curb this. For those doing intermittent fasting for other reasons, however, the dehydration effect should be no issue.

The other finding of the study was that the time of day when resistance training was done had no impact on body mass and body fat percentage. It made no difference whether training happened after eating in the evening or while fasting during the day. The duration of the study was only four weeks, but I suspect this would largely carry on, and perhaps, as noted by the researchers, training may actually be enhanced due to a larger anabolic response from fasting.

Since more and more athletes are becoming interested in fasting, studies like this go a long way to help dissuade the fears about negative performance effects. If you’ve been considering trying intermittent fasting, but you’ve had this stumbling block, now is the time to give it a shot.


1. Khaled Trabelsi, et. al., “Effect of fed- versus fasted state resistance training during Ramadan on body composition and selected metabolic parameters in bodybuilders,” Journal of the International Society of Sports Nutrition 2013, 10:23

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