Dear Doctors: I’ve heard that when you’re on a diet and you decrease caloric intake by a lot, your body will start to consume muscle for energy. It that really true? How can you lose weight and not wind up losing muscle?
Dear Reader: Discussions about losing weight typically focus on pounds, as in, “I want to lose 10 pounds.” The important follow-up question here is: pounds of what? Work up a sweat with a vigorous set of tennis, and the scale will show you’ve immediately dropped a few pounds — of water weight. You’ll gain it right back with your next beverage. (A quart of water weighs 2 pounds, in case you were curious.)
Diets that involve a drastic calorie cut do lead to weight loss, but participants wind up burning not only fat, but also significant amounts of lean muscle. That’s a bad idea, because we rely on our muscles for both strength and endurance. Muscle tissue also plays an important role in resting metabolic rate.
The answer to the “pounds of what?” weight-loss question is, of course, fat. When we set a weight-loss target, the goal is to lose fat. Or, to view it in more useful terms, we want to achieve a more healthful ratio of lean tissue to fat. Achieving and maintaining a healthful weight has many benefits, including reducing the risk of diabetes, high blood pressure, coronary artery disease, depression and even certain cancers. And, while it’s tempting to try some of the more extreme low-carb and high-fat diets that are now popular, which promise swift and painless weight loss, we believe a moderate approach yields better and more sustainable results.