A lot of people don't know that you base metabolic rate consumes a ton of energy. One prof told me that exercising merely doubled your energy requirements durin

A lot of people don't know that you base metabolic rate consumes a ton of energy. One prof told me that exercising merely doubled your energy requirements during the exercise - half for the BMR, half for the exercise. Taken in that light, exercise for an hour a day didn't do much to change your energy consumption overall. The numbers may be off, but the concept is there - it takes energy to maintain the billions of cells that make up your body. Even if they're 'doing nothing', they still live and excrete, for example.