As you can imagine, after writing a book on fasting for weight loss, I have received an astonishing number of questions in my inbox, the most common question being about fasting and muscle loss. Most people are still very worried about losing muscle if they don’t eat every 3 hours. My answer has always been, don’t worry, from my experience if you are resistance training then you will not lose muscle while dieting.

Then I got a very interesting question that went something like this: “If restricting calories doesn’t cause muscle loss, then what does it?”

Big question. We all know that people who are bedridden and on a low calorie diet lose muscle. When I started writing Eat Stop Eat, and raised the idea with various dietitians for information, they all mentioned stories of muscle loss in their patients who were bedridden on a low calorie diet.

And since I’m constantly saying that calorie restriction doesn’t cause you to lose muscle if you’re exercising, then being ‘bedridden’ (or ‘disused’ as they say in the research) is the cause of muscle loss.

Have you ever broken your arm and had to wear a cast, or did you know someone who did? Remember how thin that arm was when the cast finally came off? Put a cast on your arm and your muscles shrink faster than an expensive new shirt in the dryer.

There were no changes in nutrition, just a change in the number of muscles used and the muscle wasted away.

In fact, “plaster” is so effective in causing muscle loss that it has been used in research to study something called “disuse atrophy” or loss of muscle mass through disuse.

In a study conducted at the University of Nottingham, 22 male and female studies had casts on their right legs for two weeks. Their diets did not change, however, after just two weeks, the cross-sectional area of ​​their quadriceps (the large thigh muscles) decreased by 10%.

There are no dietary changes … but the muscle continues to decrease in size by 10%.

When you combine this information with other research that has shown that as long as you exercise and meet some sort of calorie minimum, you won’t lose muscle, you can come to the conclusion that if you don’t use your muscles, then it doesn’t really matter what you’re eating, the muscle will shrink. However, if you are using your muscles, as long as you eat at least 80 grams of protein and more than 800 Kcal a day (the amounts found in recent research work), you should not lose muscle mass.

Now, if you accidentally break your arm, Nottingham research found that creatine monohydrate supplementation can speed up the rehabilitation process, helping you rebuild your muscle and strength faster than normal.

Means:

Hespel P et al. Oral creatine supplementation facilitates the rehabilitation of diffuse atrophy and alters the expression of myogenic factors in humans. Journal of Physiology 2001; 526 (2): 625-633

Bryner RW. Effects of resistance training vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. Journal of the American College of Nutrition 1999; 18 (1): 115-121