From what has been said regarding the three classes of foodstuffs, it becomes evident that calories do not represent the sum total of nutritional requirements. Besides a sufficient number of calories, we must have a judicious distribution of these calories in terms of the three classes of foodstuffs. But how much of each must we take? Are there any minimum requirements of protein, fat and carbohydrate?

Taking up the fat and carbohydrate first, as the easier problem to solve, we may state that since both of these serve primarily as sources of energy, the amounts taken per day should be such as to correspond to the energy requirements of the body. If the average man liberates heat in the neighborhood of 3000 to 3500 calories per day, he should be given enough fat and carbohydrate to form this amount of heat. Of course, the fact should not be lost sight of that the very constitution of the protein molecule shows it to be an energy-forming as well as a tissue-replacing substance. That means that the amount of fat and carbohydrate eaten need constitute a little less than the equivalent of 3000 to 3500 calories. That means that in order that we may know how much less than 3000 to 3500 calories the fat and carbohydrate need produce, we must first ascertain the minimum protein requirements of the body.

Instinct as a Guide to Man's Food Requirements. As with all questions relating to food, the earlier experimenters on protein requirement were largely guided by mankind's accumulated experience in the matter. When the average of many thousands of examples was taken, the amount of protein consumed per day by the individual was a little more than 100 grams. If we take the rough estimate of 30 grams as being the equivalent of one ounce, the hundred grams would be the equivalent of a little more than three ounces.

Around this protein requirement of 100 grams per day there have raged battles royal, and the decisive test has yet to be made. From the purely economic standpoint this protein requirement becomes an extremely important one, because the proteins are the most expensive of the three classes of foodstuffs. If then we could, without harm to the population, replace part of the protein by the other two foodstuffs, it would be conferring a benefit on the poor part of the population, unless by so doing, our good-natured speculators would come to the rescue of their pockets and demand an increase in price for fats and carbohydrates!

Some information was shed on the subject of protein requirement by a careful examination of the diet of Asiatics, particularly the Bengalis in India. Their diet is largely vegetarian, and they consume not more than 37 grams of protein per day - about a third of what the European consumes. The Bengalis, it was pointed out, are an inferior race to the Europeans, both physically and mentally, and this inferiority was now largely attributed to deficient protein consumption.

This conclusion did not go unchallenged. Scientists attempted many quantitative experiments to arrive at some definite results. Unfortunately for the scientist, the human body, though a mechanism in some ways, is still far more than a mechanism. What holds true of chemical reactions does not necessarily hold true of body changes. Here there are so many factors over which man has as yet no control; and even when he realizes some of these factors, they are rarely so well-defined as to stand the test of experiment.

Mr. Horace Fletcher

But if scientists performed quantitative experiments, there were others, not scientists, who performed what some like to call "common-sense" experiments. A particularly conspicuous individual in this direction was Mr. Horace Fletcher, whom readers of newspapers must remember. Here was a man who had passed middle age and who had been refused life insurance because of delicate health. "Fie upon ye!" cried Fletcher; "there is absolutely nothing the matter with me, except that I eat much too much, and am not careful in what I choose." Whereupon Mr. Fletcher began by cutting down calories and increasing the time taken to masticate food. "Fletcherism" became a fad.

From our standpoint what is particularly noteworthy in Mr. Fletcher's praiseworthy experiments on himself is the relatively small quantity of protein he consumed. Mr. Fletcher's physique improved decidedly. Fatigue and lameness and colds all disappeared. Naturally enough, Fletcher attributed his success to the adoption of his modified regimen; and in this modified diet, a conspicuous feature was the small amount of protein it contained.