well, anyway, here's why muscle does not turn into fat: muscle cells and fat cells are entirely different from one another (it would be easier to turn gold into lead) and muscle cells are never going to turn into fat cells. ok, you might ask "but, dr. fuscia, won't i still get fat if i stop exercising?" yeah, you might, if you consume more than you burn. but, this is true if you never exercised at all (it's not as if adding muscle increases your chances to become obese. quite the contrary). the more muscle (active tissue) you have, the slower you will gain fat.