Fasting and Muscle Loss

Fasting doesn’t seem like it’d be the most effective means of gaining or maintaining muscle. Let’s talk about that.

First off, how often you eat isn’t nearly as important as what and how much you eat. There are some benefits of eating protein every few hours, but not doing so isn’t going to kill your progress.

Here’s the overly-sciency part, but I’ll break it down. Glucose, received mostly from carbs, is a source of energy for your body. If your body isn’t receiving the carbs, it will get glucose from other places. It can pull it from glycogen, much of which is stored in the liver and muscles, but it can also pull from amino acids found in the muscle.

The process that the body uses to get the glucose from the amino acids is much more difficult than the one to pull from glycogen, and like us, our bodies like to take the path of least resistance. So, until your stores of glycogen in your liver are depleted, your body won’t turn to the amino acids in your muscles for energy.

Most people’s livers store enough glycogen to last them for anywhere from 6-24 hours of fasting, depending on activity. One study shows that by 16 hours of fasting, the body was drawing about 50 percent of its glucose from the amino acids. By hour 28, it was taking 100 percent from it. So, most of the time, if you’re fasting for more than 12 hours, the body may begin to turn to the amino acids in your hard earned muscle for its glucose.

So, if you’re trying to build or maintain your muscle, the best plan is to not fast for more than 16 hours at a time. But, if you’re working out during the fast, that time period is significantly reduced because the activity is causing your body to draw on its glucose much more quickly.

Faster training will be a topic for a different day.


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