Q: what happens to the excess fats? how is it used by the body?

A: Your body uses fat both as an energy source and as a building/repair material for all its billions of cells. But if you overeat fats and there's excess of them they'll simply go into your fat deposits. The same is true of carbs -- carbs are an excellent energy source, but if your body has more of them than it can use, they'll simply make you fatter.