LESSON CXXIV
FOOD REQUIREMENT
DAILY ENERGY REQUIREMENT.—One hears much concerning working efficiency, i.e. the ability to do the maximum amount of work of the highest type with a minimum waste of effort. There is no doubt that the kind and quantity of food that an individual consumes has much to do with his working efficiency, and that it is consequently a matter worthy of serious consideration. Enough gasoline is used in an automobile so that there is produced sufficient power to move the car at the desired speed. So sufficient food should be used by the individual that enough energy be supplied to his body for its greatest usefulness.
Since foods furnish the body with energy, the energy which the body spends in doing its work is a measure of the fuel food needed. If the body requires a certain amount of energy for its needs, this energy, measured in Calories, can be supplied by a definite quantity of combustible food. Hence, daily energy requirements can be measured in Calories.
Scientists have done much experimenting and investigating concerning the quantity of food that individuals require. They have concluded that many factors may be taken into consideration in determining daily food requirements or dietary standards. Some of these factors are: (1) weight; (2) occupation; (3) age.
(1) Relation of Weight, Size, and Shape to Daily Energy Requirement.—In general the quantity of food required increases with the size of an individual but not at the same rate as the body weight increases. Two persons may be equal in weight, yet very different in height and shape. A tall, slender person requires more food than a short, fleshy person of the same weight. For this reason, size and shape rather than weight are found more accurate in computing the daily food requirement. However, for practical purposes, energy requirement is generally based upon body weight.
(2) Relation of Occupation to Daily Energy Requirement.—From the previous consideration of energy, it is obvious that muscular exercise, even though very slight, requires some expenditure of energy. It has been found that, even during sleep and rest, energy is required to carry on the functions of the body (such as the beating of the heart, etc.). Since the energy for both the voluntary and involuntary activities of the body is furnished by the fuel foods, it is clear that one's occupation is an important factor in determining the kind and quantity of food an individual should use.
The man who is doing hard physical work needs more food than the man who sits quietly at his employment.
The following table, showing the energy required for different conditions of activity, has been formulated by scientists: [Footnote 96: Atwater and Benedict, United States Department of Agriculture, Yearbook 1904, p. 215.]
Man sleeping requires 65 Calories per hour
Man sitting at rest requires 100 Calories per hour
Man at light muscular exercise requires 170 Calories per hour
Man at active muscular exercise requires 290 Calories per hour
Man at severe muscular exercise requires 450 Calories per hour
Man at very severe muscular exercise requires 600 Calories per hour