Physical fitness is today's hot topic. And everywhere you turn you hear something new. But is it all true?

　　The more you sweat, the more fat you burn .

　　This myth has encouraged people to work out in extreme heat or wear layers of clothes or rubber or plastic weight-loss suits in the hope of sweating fat off. Unfortunately, it's water they're losing, not fat.

　　Fat burns when it is used as a fuel source for exercise, which doesn't happen initially. When you first begin to exercise, you burn carbohydrates or sugars. It takes about 20 minutes of easy to moderate aerobic activity before the transition from burning sugars to fat begins. (Aerobic exercise is any rhythmic and continuous activity that uses oxygen and large muscle masses of the body, such as the arms and legs. Examples are bicycle riding, jumping rope, walking, jogging, aerobic dance, and swimming.) So, to burn the flab, plan on working out at least 40 minutes.

　　If you stop working out, your muscles will turn to fat.

　　If you decrease your activity and continue to eat the same or more, you may gain back that spare tire that you worked so hard to lose. It's not, however, because your muscles turned to fat. M