# How Much To Eat

( Originally Published 1921 )

I discussed briefly the subject of calories. There is no occasion for figuring the number of calories in one's food from a practical standpoint of eating for health and strength. However, we cannot consider the scientific data and records of experiments that throw light on that question of how much to eat without use of the term calory.

One of the earliest lines of research in food science was the effort to formulate dietary standards. The method of doing this was the keeping of records of the quantities of foods eaten by various groups and types of people. With the kinds and amounts of food known, it was easy to figure the total number of calories or the total quantity of food, considered as body fuel.

The following table gives the number of calories per man per day for the various occupation groups listed. These figures are for the most part the averages of the diets of many individuals, and fairly represent the conventional eating habit of Americans.

QUANTITIES OF FOOD EATEN BY VARIOUS OCCUPATIONAL GROUPS

Calories per day
Football teams 6,590
Lumbermen 5,420
Well Paid Laborers 3,925
College Clubs 3,580
Professional Men 3,480
Farmers 3,415
Southern Negroes 3,395
Skilled Mechanics 3,355
Teachers 3,195
Garment Workers 3,145
Office Clerks 3,125
Salesmen 2,980
Poorly Paid Laborers 2,810

It is seen that the amounts of food eaten by these different groups of people vary widely. The chief causes of these variations is the amount of muscular labor performed and the amount of money available to pay for the food. If individual data be given for different men, or different families, even in the same occupational groups, the figures would also show a wide range in quantities of food eaten.

A very interesting check on these figures on the amount of foods commonly eaten by Americans was made by the Hoover Food Administration during the war. Statistics were secured of the entire quantity of food consumed in the United States. Figured out according to population and reduced to a unit of man per day, it was found that the average American man consumes 3,424 calories per day. This backs up very convincingly the figures secured by measuring the foods actually eaten by various groups of individuals.

From the studies of the amount of food that men do eat, food scientists tried to derive definite standards which should serve as a guide to tell men how much they should eat.

Such a table of food standards was drawn up by Atwater and was widely published by the United States Government. It was as follows:

ATWATER TABLE OF FOOD STANDARDS

Calories

Men at very hard work 5,500
Men at hard work 4,130
Men at moderate work 3,500
Men at light work 3,150
Men at sedentary occupation or women at moderate work 2,700
Men taking no muscular exercise or women at light work 2,450

This seems to us now to be a rather foolish method of reasoning. To assume that what men dodo is what they should do is certainly not the way to learn the truth or to make progress in the world. By a similar method of reasoning we might determine the average amount of stealing that men do and thereby derive a standard of thieving. It also reminds one a little of the old lady's assurance that every one of us must eat his peck of dirt.

These illustrations are a little far-fetched, but even in more closely related instances we can see the fallacy of using the average man as a standard or guide for those seeking the best way to live. The average amount of exercise taken, at least by the city dweller, would hardly be accepted by the ardent physical culturist as a guide for his own practice. In the matter of the body weight this same error of accepting the average as the standard has actually prevailed—as will be fully brought out in our chapters which discuss the control of the body weight.

These dietary standards derived, from observation upon average eating habits were further checked, and to a large extent: verified by a more elaborate and scientific method. I refer to the use of the Respiratory Calorimeter. This interesting scientific device consists of an air-tight chamber properly insulated against loss of heat. If a man, or an animal, be placed in such a chamber it is possible to measure very accurately the amount of oxygen consumed and carbon dioxide given off, and so determine the amount of oxidation that occurred. By further measurements may be determined the amount of heat generated and the mechanical labor of the test subject. By the usual chemical methods, both the food and the excretory products may be analized. When such researches are continued for sufficient time it is also possible to calculate from this data, checked by the changes in the body weight, the accumulation or loss of fat or protein substance from the body.

By such elaborate and thorough investigation scientists were able to learn just how much food the body seems to require and how that food was consumed or expended in the production of heat, muscular work, or in additions to the body substance.

The scientists reasoned that when a man's body was not increasing in weight and he was, therefore, utilizing all food eaten in the physiological and muscular activities, he required the exact amount of food so consumed. Experiments in giving him less food resulted in a loss of body weight which seemed most positive evidence that the amount of food could not be safely decreased.

This was the general state of scientific knowledge on the subject, "how much to eat,"- at the beginning of the war; moreover, this knowledge essentially verified the earlier food standards that had been determined by investigating how much people do eat.

However, many health authorities and students of food problems who derived their opinions from practical observation of the effects of food on health and strength questioned these food standards which had been determined by elaborate scientific research. Among physical culturists and health reformers generally the opinion prevailed that over-eating was not an exceptional, but a general fault. Such men as Horace Fletcher and his associates had shown that better health could be maintained upon smaller food allowances. When Mr. Fletcher was sixty-three years of age he was tested in the Calorimeter and was shown to oxidize or metabolize nine calories per pound of body weight. This was the lowest ratio of metabolism observed among eighty-nine men tested. Yet Mr. Fletcher at this time was by no means poorly nourished, for he weighed 180 pounds, and was not a tall man. His years of careful eating had made it possible for him actually to get fat on less food that other men seemed to find necessary for existence.

Mr. Fletcher believed the chief benefit which he derived from his careful eating habits was due to thorough mastication. Dr. Chittenden, who experimented with Mr. Fletcher's methods upon a group of soldiers and athletes, was of the opinion that the benefits were due to the use of smaller fluantities of protein. None of these investigators laid chief stress upon the matter of total food quantity, though in all such cases there was a tendency to reducc it.

With the coming of the war, all manner of re-search in food science was greatly stimulated. Food economy became imperative for the whole world, and in many countries there was not enough food available to maintain anywhere near the former eating habits of the people.

Great suffering, and loss of health and of life resulted because of the food shortage during the war and the years immediately following; but if the teachings of the orthodox food science regarding the amount of food necessary had been true, the world's death list from food scarcity would have been enormously greater.

The European nations found out that men could live on much less food than they customarily do eat when their eating habits are determined by appetite, and there is ample food and sufficient money available to pay for it.

It is not a convincing argument to claim that the Germans or other peoples were benefited by the food restrictions imposed by war necessity, yet many careful observers of war conditions were convinced that, as far as food quantity alone was 'concerned, the restricted diet was actually beneficial. The chief suffering came from the restriction of food variety and the depreciation of food quality. Not only were the poorer classes unable to get enough food, but all classes suffered from lack of proper food; especially from shortage of milk, butter and eggs, fats and fresh fruits and vegetables. The diet in many. in-stances was reduced virtually to potatoes and cereals, an inadequate diet even if quantities were unlimited. Moreover, there was such a vast deal of suffering and privation from other than dietary causes that observations of the health, efficiency, or death rate of the peoples under war conditions are practically worthless as far as deciding dietary questions is concerned.

In America, however, scientific researches were conducted to determine the effect of reduced quantities of food, and from these re-searches we have gained much new knowledge. The investigations that I particularly refer to were conducted by Dr. Benedict of the Carnegie Institution.

Dr. Benedict experimented upon the students of the Y. M. C. A. College at Springfield, Mass. Many of the subjects of these experiments were taking the training course as Y. M. C. A. physical directors and all of them were taking gymnasium work, while many were active in outdoor athletics.

The diet provided in the College dining hall supplied 4,000 calories per day. This is a rather heavy diet, but the students were very vigorously exercised young men. Not all of these men may have been in the habit of eating 4,000 calories a day, but from actual records it was evident that all of them were consuming well above 3,000 calories per day.

The method of the restricted diet experiment was to cut down the food allowance of each man individually until he had lost ten per cent of his weight. After such a loss of ten per cent of each man's weight, his food was carefully adjusted to a quantity that would just maintain the body weight at ninety per cent of the original figure. The amount of food that each man required to maintain this restricted weight was then determined. The amounts varied according to the size of the men and their habits of activity, and ranged from 1,600 to 2,500 calories per day. The average figure for the group was 1,950 calories per day. This was less than half the food that had been previously provided for these men, and certainly not over two-thirds the amount that any such group of men would have consumed if following the usual American eating habits.

According to the old pre-war teachings of science it would have been thought that men could not have maintained their health and physical efficiency upon such small quantities of food. But these men did maintain normal health, and elaborate studies of both their mental and physical efficiency showed that they suffered little, if at all, due to living on the much reduced quantity of food. This is the more remarkable when we realize that these men did lose ten per cent of their weight and that this loss of weight occurred in men who entered the experiment as active trained athletes and were not carrying a lot of excess fat. Their muscles may have been actually reduced in volume, though probably the chief loss in weight was due to a loss of a small portion of fat that even the athletic man carries, if he be a heavy eater. The nude photographs of these men after their weight reduction still showed them to be fairly well muscled and seemingly in fit physical condition. Their athletic records and physical tests on reduced diet showed that they had lost neither strength nor endurance.

What really seems to have happened is that the muscular tissues that they retained became more efficient. Tests in the respiratory calorimeter showed that they were able to perform a given amount of physical labor with a smaller consumption of oxygen, which means that less food substance. was oxidized or consumed. The physical engine actually became more efficient, and turned out more labor per pound of "human coal."

This extremely restricted diet was not, how-ever, without certain effects which many people would consider undesirable. For instance, the rate of the heart beat was distinctly lowered; the circulation being slower, the skin temperature was slightly reduced, and the men complained of being chilly and were obliged to dress more warmly. The blood pressure was also lowered, a thing which most physicians consider an indication of health improvement.

On the whole, we may summarize the findings of these extremely interesting experiments by saying that the body has the power to adjust itself to various food quantities or nutritive levels. While the usual result of excessive eating is obesity, yet it is apparent that one may eat more than he needs and yet not get fat; he merely disposes of the extra food by using it waste-fully. From such overeating the rate of the heart beat and respiration are increased so that more food fuel is oxidized with the production of an excess of body heat a very convincing argument in favor of a light diet during hot weather. With the larger quantities of food the body simply runs at higher pressure; all physiological activities are speeded up or more extravagantly conducted.

Just how much benefit or harm may come either from this higher pressure living or the physiologically more efficient low pressure living is not so easily determined. Of this, however, we have convincing proof: minimum eating is not immediately harmful, nor is there any danger or loss of efficiency from a reduction of weight somewhat below the amount usually carried, even of the athletic type.

An experiment of a few months' duration proves but little as to the long run effects that might occur from the same conditions maintained for a life-time. Upon this subject we will take up some interesting facts in our chapter: "The Diet in Old Age."

From all scientific data now available, as well as from practical observation, I would say that the most nearly ideal dietary standards of food quantities would be midway between the old At-water standards and the minimum figures attained in Dr. Benedict's experiments. This should give us a figure of about 2,500 calories per day for a man of average size at moderate work, which is 1,000 calories less than Atwater's standard.

The dietary figures for women have usually been given as eighty per cent of those of men. ' I believe that for the average woman, who takes very little exercise and is inclined to be fat, even this proportion is too high. For the woman who is physically vigorous and active, as she should be, the proportion is about correct, which would give us a standard of 2,000 calories per day for the average woman at moderate work, in the place of 2,700 calories, as given in the Atwater standard.

I give these figures only to show clearly the changed views on the question of how much to eat. In actual practice no dietary standard of so many calories per day is of practical use to the individual. In the first place the figuring up of the calories of one's diet is an unreasonable task to impose upon any one but a scientist. In the second place, such general standards are worthless when applied to an individual case, be-cause individual needs vary so widely. The chief cause of this variation is the actual size of the active body or the weight of muscular tissue, and this fact is difficult to determine. The bigger a man is, that is, the more muscle he has, the more food he will need, but the heavier, that is, the more fat he has, the less food he should eat. Lastly, there is no way to tell just what is meant by light, heavy, or moderate work. A man may feel that he is working very hard, merely because of monotonous labor, unpleasant surroundings, or mental strain. Another man working pleasantly with a variety of muscular movements may seem to be working less hard, though he would require more food fuel for his activities.

There is only one practical method by which to gauge the amount of food one should eat; and that is by observing the weight of the body and one's general feeling as to strength-and health. The ideal food quantity is that amount which will just maintain a feeling of super bodily strength and endurance and ideal weight. Here again, of course, we are dealing with a standard upon which peoples' opinion may differ. Al-most any one has a fairly definite conception of the ideal form of the human body. With proper muscular development this ideal form will, for each individual, be a sufficient guide to the ideal weight. The practical trouble is that very few individuals, under the conditions of modern civilization, have sufficient muscular development.

If a lazy, unexercised man, five feet eight inches in height takes as his model a perfectly developed athlete of the same height who weighs one hundred and sixty pounds, and the lazy man attempts to attain the athletic weight by eating rather than by exercise, the result will be a fat and over-fed man. On the other hand, should an exceptionally well muscled man reduce his food until it resulted in his coming down in weight to reach the average figure, it would merely mean that he would lose the exceptionally fine physique that he had built up. In practice there is much less danger of the latter error than of the former one.

The ideal plan is, therefore, to eat just enough to maintain a feeling of strength and all around vigor and with the body in a well-muscled condition and without any visible evidence of surplus fat. Even a very slight increase of the body weight above this muscular minimum indicates over-eating. The condition of the body is usually most easily determined by the presence or absence of fat on the abdomen. The man in first-class physical condition has no more fat upon his "stomach" than he has on his arm, and the form of the abdominal muscles may be felt beneath the skin as readily as the biceps. Few men maintain such fitness, but that is no proof that it can not and should not be maintained. Most men do overeat and under-exercise; and most men are too fat, and die from ten to twenty years before their time because of it.

The above discussion has been written primarily from a masculine standpoint. The feminine form naturally carries less muscle and more fatty tissue than the masculine. There are fundamental physiological reasons why this should be so. Nature adapted the feminine body to a more ready storage of surplus nutrition as a preparation for child-bearing. Our ideas of feminine beauty also require the presence of more fat in the feminine than in the masculine form. This ideal of fatness in feminine form was formerly carried to an extreme, which the present generation is trying to get away from. The modern woman wishes to be "slender," yet even her ideal of slenderness usually means a comparatively fat condition, because of the lack of muscular development. The true ideal of feminine form is only maintained by the athletic type of woman, and a form maintained by over-eating instead of by proper exercise is not a true or lasting form of beauty.

Those who are obviously under-weight or over-weight will find their problem most thoroughly discussed in later chapters. For the individual who is of approximate normal weight I suggest an experimental cutting down of the amount of food eaten until it results in a loss of from five to ten pounds of weight. Such an experiment will do you no harm and you may find that it will produce a marked benefit in health and efficiency as well as in food economy. In such cutting down of food quantities, as in reducing from obesity, it should be the starches and fats that are eliminated. Indeed, if you have been living upon the conventional diet, almost invariably too rich in the fat-forming foods, you are likely to find that the adoption of the type of diet advocated in this book will result in some loss of weight without any conscious effort on your part to reduce the food quantity. If so, be reassured that this loss of weight will prove beneficial.

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