All of our metabolic rates are different because we are all cut from a different cloth. Every cell in our body burns some kind of calorie all the time, even while we sleep. But, not all cells are created equally. Fat tissue burns the least amount of calories, while lean tissue burns quite a bit more. Muscle tissue, even at rest, is the most active energy burning tissue of all. That muscle tissue works really hard at rest! Therefore, the more muscle you have, the higher is your metabolism.