The Scary Thing That Happens to Your Muscles on a Crash Diet

Now that sundress season has arrived, you might be tempted to drop a few pounds on a juice fast or a super-low-calorie plan. Bad idea. Not only do crash diets pretty much never lead to long-term, sustained weight loss—turns out they also do a number on your muscles. A new study presented at the European Congress on Obesity found that crash dieting depletes approximately three times more muscle mass than weight-loss plans designed to subtract pounds more slowly. 

Researchers at Maastricht University in the Netherlands put 25 study subjects into two groups. The first group embarked on a five-week diet consisting of a scant 500 calories a day. The second group also went on a diet, but theirs was spread over 12 weeks and allowed for 1,250 calories per day (which is still pretty low if you ask us—particularly if you're active). At the end of both diets, study authors discovered that participants in both groups racked up an average of about 19 lost pounds. The difference was, the study subjects on the 500-calorie plan lost 3.5 pounds of muscle mass, while the 1,250-calorie group lost only 1.3 pounds of muscle. In other words, among the super-low-calorie dieters, 18 percent of their weight loss was attributed to muscle loss, while only 7.7 percent of the other group’s weight loss was muscle. 

What's so important about preserving muscle mass? Muscle plays a big role in your resting metabolic rate, write the study authors. The thinking is, the less muscle mass you have, the more likely your metabolism is to slow down...making it a lot easier for you to regain the lost weight once you return to your usual eating habits. The researchers are continuing to study the participants to see how quickly they regain weight, how many pounds they put back on, and how muscle loss plays into all of this. In the meantime, take this as yet another reason to lead an overall healthy lifestyle that promotes weight loss and/or maintenance—rather trying a plan that promises to help you drop major pounds quickly.  

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