Muscles Don't Turn into Fat

If you are afraid to exercise because you think that after you stop, your muscles turn to fat, you are out-of-shape for the wrong reason.

Muscles can't possibly turn to fat. When you exercise, your muscles become larger and stronger because exercise causes extra protein building blocks, called amino acids, to deposit in muscles. All day long, amino acids pass from your muscles into your bloodstream and then back into muscles, with exercise as the major stimulus to force amino acids back into muscles. When you stop exercising, fewer amino acids go back into muscles and they become smaller. Amino acids that do not go back into muscles, are picked up by your liver. Since your body has no way to store extra protein, your liver uses them for energy or converts them into fat. So if you stop exercising, you have to eat less or you will become fat, but muscles never turn into fat.

Checked 3/19/14

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