What is Metabolism?

The amount of potential energy contained in food.

The process by which your body converts food into energy

The minimum number of calories for the body to sustain itself and stay alive each day at a state of rest

"The process by which your body converts food into energy", sounds more accurate.

" The amount of potential energy contained in food", is basically a long way of saying - Calories.

So, I would go with the one that talks about the process of converting food to energy.