Body-Weight

According to our general plan of research, observations were to be made upon these men, first, during a period of insufficient food, and second, during a period of maintenance diet at a lower nutritional level. The most obvious result of a reduction in the amount of food taken is the loss in body-weight caused by the fact that body-reserves are drawn upon to supplement the inadequate diet. Outside the physiological laboratory, therefore, no method is so satisfactory for determining differences in nutritional level with special reference to drafts upon or storage of body-material as long-continued observations on the body-weight. Carried over a period of several days, if not weeks, these are truly indicative of the state of the body-reserves. A careful study of the body-weights of our squads, both prior to and subsequent to diet reduction, is therefore of importance.

To shorten the preliminary period of insufficient food in which the subjects were brought to the lower nutritional level, it seemed desirable to reduce the body-weight of the men as quickly as possible. The reduction of body-weight has been the subject of a great deal of investigation, and many practical methods have been suggested and extensively applied. These fall for the most part into a few well-defined classes. First, the body-weight may be rather rapidly reduced by complete fasting. During the 31-day fast made in this Laboratory the body-weight fell about 1 pound for each day of complete fast, although the loss was much more pronounced in the earlier part of the fast than in the latter part. A second method is to reduce materially the food in the diet. By giving less food than is actually required, the deficiency is made up by drafts upon the body-material. Third, the reduction in body-weight is accomplished by excessive exercise. In other words, by keeping the food intake at a constant level and by increasing the demands for energy, the body-weight may be reduced. Fourth, the body-weight may be rapidly lowered for specific short periods by the use of purgatives. Fifth, in addition to exercise and practice, a popular method of reducing weight has been to take very hot baths or to induce profuse perspiration by excessive clothing. Undoubtedly this removes a considerable amount of water from the body, but it has practically no influence upon the organized tissue.

The method of losing body-weight by changing the character of the diet has, we believe, never been used, although there is no particular reason why this should not be successfully employed. When the carbohydrate in the diet is in large part replaced by fat, it has been quantitatively demonstrated by Benedict and Milner1 that there is a very considerable discharge of water from the body, apparently held by the carbohydrate previously ingested. Undoubtedly this condition is accompanied by a considerable reduction in glycogen content of the body, and glycogen is known to hold considerable quantities of water.

In order not to complicate the problem by producing excessive loss in weight due to drafts upon body material as the result of excessive muscular exercise, the simpler form of weight reduction resulting from insufficient food, with approximately constant muscular activity, seemed the best procedure. Our problem here, as stated earlier, is a study of the influence of insufficient food and not primarily the study of a loss in weight as a result of excessive exercise. This latter factor presents certain problems that of themselves should receive special experimental treatment. In the first part of the study, a combination of two methods was used with some of our subjects in that the reduction in diet was combined with excessive muscular activity, as these subjects, especially those light in weight, found it difficult to reduce upon the general diet supplied to the squad. Our records show that in certain cases very considerable activity was engaged in to secure the reduction in weight, since all the men were informed at the beginning that they were supposed to reduce their weight 10 or more per cent.

Normality Of Initial Body-Weights

The initial body-weights of these men are of interest as showing whether they were normal or above or below the normal weight. As would appear natural, it was easier for a man who was above normal to lose weight than a man who was under normal weight. If the selection of subjects could have been made on the body-weight basis and an equal number of men over and under normal weight chosen, the conditions would have been ideal. Such a selection was impossible; but a number of the men in Squad A were under the normal weight at the beginning of the experiment. For the purpose of showing the relationship between the actual weights and normal standards, we have collected the body-weights of the men in Squads A and B and have compared them with the so-called normal weights given in a medico-actuarial mortality table.1

1 Benedict and Milner, U. S. Dept. Agr., Office Exp. Stas. Bui. 175, 1907, p. 225; abstracted by Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 176, 1912, p. 92.

Although precautions were taken in all instances to weigh the men under exactly the same conditions2 as to the absence of food in the stomach and after a night without drinking-water, nevertheless the possibility of retention of urine, and especially of feces, makes small changes in weight entirely without significance. Accordingly, while the weights are given in our tables to the tenth of a kilogram, it must be recognized that differences of less than one-half kilogram are without consequence.

The statistics for Squad A are given in table 9, together with the normal weight for age and height as taken from the Medico-Actuarial Mortality Table (see column a). The initial weights of the squad are given in column b, and the difference between the normal and initial weights in column c. An examination of the initial weights for Squad A just prior to diet reduction as compared with the standard weights (see column c), shows that Moy, Pec, Tom, and Fre, were measurably under normal weight, although Moy was but 0.5 kg. below normal. Tom, who was slender and tall, of sedentary habits, and not given to athletic exercise of any kind, was 6.8 kg. less than the average weight for his age and height. Pec, who was a finely trained man, 44 years of age, and of a well-seasoned athletic type, was 2.2 kg. less than normal. Fre dropped out of the experiment in about two weeks, so there were actually but three men in the squad who were under normal weight. Special attention should be given to these three men in the discussion of the effects of the diet. A number of the men had a distinctly excess weight, six being 4 or more kg. above normal. Can, who showed the greatest difference, was the heaviest man in the squad. It is deemed of particular significance that these differences between normal or average body-weights and true weights are so great, with a reasonable proportion of the men varying either one way or the other from the standard. The influence of a restricted diet upon these two types of normal individuals should, therefore, be instructive.

1 Medico-Actuarial Mortality Investigation. The Association of Life Insurance Medical Directors and The Actuarial Society of America, New York. 1912. 1, p. 38. table 4. This investigation gives data as to the expectancy of life according to height and weight (see vol. ii) as drawn which are somewhat inaccessible to most readers, but which fortunately have been published by Dr. Joslin in his book (Joslin. Treatment of Diabetes Melutus. 2d ed.. Phila., 1917. p. 67).

2 See technique used in weighing subjects, outlined on p. 75.