Carbohydrates are organic compounds important as food to plants and animals and derived from carbon dioxide and water, through the action of sunlight on chlorophyll. Proteins are much more than simple bodybuilders. They are extremely complicated molecules, or combinations of atoms made up of amino acids. They often combine with other substances, such as carbohydrates, fats, and nucleic acid. The latter is a biochemical agent that includes the master chemical DNA. Of the well-known classes of food substances, namely, carbohydrates, fats, and proteins, only the last-named is used for the growth and repair of the body structures. When completely oxidized outside the body, as in a Bomb calorimeter, it has been shown that the calorific value per gram of these foods is as follows: Carbohydrates 4.1, fats 9.3, and proteins 5.0 Calories ((Harrison 41). It is possible to speak of these as the physical energy values to distinguish between these and similar energy values obtained from the oxidation of these same foods in the animal body, the physiological energy values. The distinction is not an exact one since no difference in the energy output is obtained from Carbohydrates and fats when they are oxidized in vitro or in vivo. In both instances, the energy liberated is always quantitatively identical irrespective of the rate at which it is set free, provided, of course, that the oxidation is complete. The end-products of the oxidation of these two substances are the same under all conditions, namely, carbon dioxide and water (Harrison 44). Good carbohydrates are substances in their natural state. This category involves food that has not been altered or changed by people. The benefit of good carbohydrates is a low glycemic index. Examples are fruits, vegetables, beans, nuts, cereals, etc. In contrast, bad carbohydrates are those substances processed by people. This type is dangerous for human health as it can cause obesity problems and other diseases. The most popular food with bad carbohydrates is candy, baked goods, and sodas. In general, the physiologic energy value of proteins is, on the contrary, less than its physical energy value. It is well known that while certain Oriental peoples are capable of strenuous exertions on a diet that consists mainly of carbohydrates (rice) the Eskimo of the far North depends primarily upon a diet of protein and fat for his energy supplies (Mielke et al 98). Since the major portion of the food of any physically active people is employed in supplying the energy requirement for muscular activity, it is obvious that in these two groups of individuals whose diets vary so markedly, yet who are probably equally vigorous, the ultimate source of muscle energy must be widely different. Ultimately the energy needs of the body are derived almost wholly from the body proteins themselves as the stores of body fat are exhausted. The chief and probably the entire burden of exercise usually falls upon carbohydrates and fats as energy sources. It is generally distributed between these two according to the diet on the days preceding the exercise. The more carbohydrates eaten the greater is the amount which is oxidized and the respiratory quotient rises, but when the carbohydrate intake is low