A day laborer needs 0.28 of a pound of protein a day with enough fat and carbohydrate to give a fuel value of 3500 calories. A professional man requires 0.25 (1/4) of a pound of protein a day. Much more than this is usually taken. This means from 1/3 to 1/2 a pound of lean meat.
Nothing is lost in Nature’s distribution of force and energy. Everything accomplished in life, either in the physical handling of material, the brain work in planning the constructions, the mental movements of thought in art, literature, or science, are all representatives of the heat and energy released from the body, and every man and woman should endeavor to make the body yield as large an income as possible in the expression of this energy. In order that it may do so, it must be used with intelligence, just as any other great machine must be used intelligently; it must be fed, exercised, and rested judiciously.
CHAPTER V
REPAIR AND ELIMINATION OF WASTE (METABOLISM)
The work of the body never stops. If it is to be kept in thorough working order its tissues must be rebuilt as incessantly as they are torn down in the process of producing heat and energy. These chemical changes are called collectively metabolism.
They are divided into two groups: the chemical process of building up complex substances from simple ones is known as anabolism; the chemical process of oxidizing and breaking down the complex substances into simple ones, so that they are in a state to be excreted, is called catabolism. While the process of oxidation in catabolism is going on, heat and energy are set free. Many of the chemical changes in the body are catabolic in character. This work never ceases—even in sleep.
It is not enough that the proper foods be furnished the body in kind and quantity. The essential thing is that the system be kept in condition to assimilate the foods to its needs and to promptly eliminate the waste. Few people assimilate all of the foods eaten.
By assimilation is meant the process by which foodstuffs are made soluble and diffusible, so that they can pass into the blood; also, the metabolic activity by which the food is converted into cells and tissues.
Truly the body is a busy workshop. Think of the billions on billions of cells being formed and destroyed every instant in the liberation of heat and force! Think, also, of the necessity of perfect circulation to bring sufficient blood to the lungs, that it may gather the oxygen and carry it, without pausing for rest, to every tissue of the body! Even in sleep this stream continues incessantly.
There is also a great lesson here in the law of supply and demand. When the body is at mental or muscular work, the potential energy liberated leaves through muscle or brain, as energy, and is expressed in the result of the work. When the body is at rest, energy leaves it as heat (excepting such part as is necessary to carry on metabolism, circulation, etc.).
If much muscular energy is called for, a deep, full breath is instinctively drawn to supply the oxygen necessary for the added force.