The body has often been called a living engine, for it performs work and generates power. In other words, it is a living machine. All engines are run by the use of some kind of fuel. Coal, wood, gasoline and other substances are constantly fed to mechanical engines. Each type requires its own particular kind of fuel. In order to do its work properly, the human engine requires the right kind of fuel just as does any other engine.

Food As Fuel; Other Uses

Food then is required by the body to supply heat and energy; but fuel foods are not the only kind required by the living mechanism, for the body is able to do what no man-made device is able to accomplish. When the parts become worn out, the living system uses food to repair the wasted tissues and bony structure. Not only can the body do this; but that it uses food for growth is constantly manifest in the develop-ment of children. Therefore, tissue-building or repair foods are required as well as fuel foods.