In interpreting this loss, we must give consideration to the figures obtained for Tow, although he was not included in the chart. Tom's nitrogen loss was but 45.74 grams for the entire period, while the average for the other 11 men was 175.0 grams.1 If our theory with regard to the nitrogen stimulation is sound, one would expect normally to find a less pronounced effect on metabolism with Tom than. with any of the other men. As the data were being prepared it appeared that there was no profound difference between the men on this basis. A more careful analysis of the data given for Tom shows that the total metabolism of this subject fell off very markedly, as indeed did the metabolism per kilogram of body-weight and per square meter of body-surface. Hence we have with Tom identically the same picture noted with all the other members of the squad, although his loss of nitrogen was on the whole but one-fourth that of the average for the 11 other members of the squad and but one-fifth that of 3 other members of the squad. At first sight this would appear to be a distinct argument against the nitrogen-stimulation theory. On the other hand, we must point out that, at least during January, Tom was in a distinctly poor physical condition. In fact, he was quite wretched during part of December and was operated on for hemorrhoids. No member of the squad seemed to find more difficulty in reducing his weight than he did. He presented a distinctly exceptional case throughout the entire period of observation. As frequently stated, he was the most sedentary in habit of the men in the squad. In view of the direct findings with Tom, therefore, we must advocate the nitrogen-stimulation theory with a certain degree of caution.

The picture presented by these men on reduced diet is similar in certain ways to that noted with diabetics who have been undergoing the Allen fasting treatment. Prior to the Allen treatment the metabolism is very high, being on the average 15 to 20 per cent higher than that of normal individuals of equal height and weight. Following the Allen treatment the metabolism becomes very much reduced. Not only does it fall to normal, but is actually lower than that of normal individuals of the same height, weight, and age. The dietetic regime of the diabetic, together with the course of the disease, almost invariably results in a great loss of fat and not a little nitrogenous tissue; hence we believe that the loss of nitrogen as well as loss of flesh in the diabetic contributes towards this lowered metabolism after the cellular stimulus of acidosis has been removed by the Allen fasting treatment.

1 It should be noted that these figures are for the entire period of the experiment, while those in table 71, p. 351, do not include the last week.

Caloric Requirement For Weight Maintenance

In the discussion of the caloric intake at weight maintenance (see p. 283), emphasis was laid upon the fact that if the body-weight were held at a constant level for a sufficient length of time (probably months rather than weeks), the net caloric intake could be rationally taken as a measure of the caloric requirement.

Certain difficulties were experienced in finding sharply marked periods of body-weight maintenance covering a considerable length of time in this series of tests, and in no other phase of the research do we regret more the necessity for the uncontrolled period during the Christmas recess. There were, however, two periods of reasonably constant weight which appear on the several charts for Squad A. From an inspection of these data we inferred that weight maintenance at the lower level was held with net calories ranging from 1,600 calories for Kon, Pec and Tom to 2,500 calories for Can. The average for the squad was approximately 1,950 net calories. Since the intake prior to diet restriction was somewhat over 3,000 calories, and Squad B, living under substantially the same conditions aside from diet, required nearer 3,800 calories, it can be seen that the diet for Squad A at these periods of weight-maintenance was a reduction of from one-third to nearly one-half of the normal diet.

Emphasis must be laid again, however, upon the fact that the body-weight is an extremely unsatisfactory and indeed crude index of caloric needs, unless maintained for a much longer period of time than was possible in these experiments. Recourse was had, therefore, to other criteria.

Basal Gaseous Metabolism

From two entirely independent types of respiration experiments certain fundamental data were available to show profound alterations in basal metabolism of all of these subjects following the reduction in diet. These reductions in basal metabolism were not only absolute - that is, each member of the squad had a basal metabolism very much lower at the end of the experiment than at the beginning - but they were likewise relative, for the basal metabolism on both of the two usual comparison bases, namely, the heat production per kilogram of body-weight and per square meter of body-surface, showed reductions approximating 15 to 20 per cent. On the more logical method of comparison of the basal metabolism with the predicted values from a series of tables based upon an extensive study of normal data obtained in this Laboratory, it would likewise seem that whereas these men at the beginning of the experiment showed a normal basal metabolism perceptibly higher on the average than that predicted for men of equal weight, height, and age, at the end of the test they all showed strikingly lower values than the predicted values from the analysis of a large group of normal people. Under the circumstances, therefore, the evidence is clear that the reduction in basal metabolism is a real one. The fact that the body-weight index implied a maintenance caloric requirement over one-third or nearly one-half that prior to diet reduction, while the gaseous metabolism suggests a lowering approximating only 15 to 20 per cent, is somewhat difficult to explain other than on the ground that the body-weight data used for comparison were for altogether too short a period. From an analysis of the chart it can be seen that the influence of the reduced diet on all factors was a progressive one, with a rather rapid effect shortly after the reduction in diet began, and a tendency towards constancy coincident with constancy in body-weight.