Originally Posted by
BigAura
Untrue, a body wants to use fat before burning muscle. After depleting it's storehouse of glycogen, fat is where your body wants to get its energy, assuming it has a intake calorie deficit. Fat is the way a body stores excess calories for long term future use, that's it's purpose.
Not quite true either.
That really depends in which "gear" your body is at the time. If you are doing low intensity workout your body will (after depletion of glycogen) use mainly fat as energy source.
But if you're doing high intensity workout your body will tear down muscle mass as it can obtain energy from muscle tissue much faster than from fat.