Page:Popular Science Monthly Volume 83.djvu/351

Rh put into a calorimeter at Middletown, Conn., it was found that ho lost from his body nearly if not quite as much heat as the average man of his age and stature. To keep himself in an equilibrium of substance it would therefore be absolutely necessary for him to take at least this quantity of potential energy in the form of food.

A few months ago a certain New York daily widely advertised the light diet by sending on foot to Chicago a woman who claimed to be living on nuts, salads, orange Juice and the like. When she arrived at Chicago it was found that she weighed some 12 pounds less than when she left New York and yet the feat was declared to be a "triumph" of the woman's regimen of light foods. As a matter of fact she had not lived on these light foods alone, but had lived largely at the expense of her own body fat. In other words, she had a large part of her fuel for the trip already in storage. If the twelve pounds which she lost were all fat, as it probably was, this alone furnished a large part of the energy of walking for the forty days (I believe it was); for every ounce of fat burned from her own tissues gave about 250 calories of energy and in 12 pounds there would be 48,000 calories or about 1,200 calories a day. If she had added 4.8 ounces of fat or a little more than twice as much starch or sugar every day to her bill of fare she would have arrived in Chicago weighing as much as when she left New York.

Cold weather raises the requirement for energy, for the body loses more heat to its environment, unless this heat is kept in by warm rooms or warm clothing. The law of energy requirement applies most severely therefore to those who can least afford to buy a large supply of food. How important it is that their money should be made to go as far as possible! The pure-food law at present operates to protect those who use more highly flavored foods and drinks rather than the poor. If every kind of food purveyed in packages, tins, bottles, etc., bore a label stating its energy value the poor and all would soon learn how to make the money go farthest.

When it comes to the actual task of calculating the body's requirements it is customary to begin with minimal conditions. A person, uses the least energy when he is resting and fasting and is kept warm—lying in bed for example. When he moves about—that is, does muscular work, when he digests a meal, or when he is exposed to cold, he uses more energy. The average utilization in twenty-four hours under minimal conditions is about fourteen calories per pound of actual body weight, or for a man of average weight (154 lbs.) 2,150 calories. We should not miss it far if we should say that a person sitting up would use one calorie per pound more (2,300). And if he digests three meals a day he uses an additional calorie per pound (2,450). If, now, he does light muscular work, like typewriting, he uses about 25 calories per hour for this work, or in eight hours 200 calories, making the total for a man of average weight 2,650 calories.