Let's simplify this: In common parlance, a calorie is a measure of the amount of energy present in a particular food. The calories we consume through food are more than what our daily activities require. Hence, we overfill our bodies. Our body does not waste these excessive calories, instead, it stores them by converting them from food to fat. In order to burn this unsightly storage of fat, we need to reverse the process. We need to consume less than we need to fuel our daily processes, and force the body to use the available fat storage as the energy source of the body. And to reduce calorie consumption, we need to focus on light food items.