Myth #8: When you stop exercising, your muscles turn to fat.

Truth: Lack of exercise does make the muscles shrink, reducing the body's calorie-burning rate. The lack of activity itself further reduces the number of calories you burn. So people who stop working out are indeed in danger of getting flabby.

But that doesn't mean that muscle actually turns to fat - they're totally different types of tissue. Nor does it mean you're doomed to gain fat around the muscles after you stop exercising; you just need to cut back on the calories you consume. (Of course, the best way to stay slim is to eat a lean diet and continue to exercise regularly.)