I The Caloric Concept of Weight Control, pt. The Caloric Concept of Weight Control, pt. I by Tom McCullough MEd. Everything we eat is used to produce energy or stored for eventual use. This energy is measures in calories.
Calories are nothing more than a unit of heat used to express the energy value of food.
The second largest expenditure of energy for the average person is that used in activity. Of course an athlete could easily burn enough calories to make this the largest expense of energy. The third, and perhaps the most insiginificant expense of energy, is that of the thermic effect of food. The process of digesting, absorbing, and assimilating the various nutrients actually require energy for calories. Although this thought may have some validity and has certainly been used for dieting, other factors must be considered-including the harmful strain on liver and kidney function that can be brought on by excessive protein intake.