524 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



In analyzing the figures obtained in these experiments, one is con- 

 fronted by the difficulty of selecting the proper normal value for com- 

 parison. As previously stated, it is obvious that the only one that can 

 be logically selected is that for January 6, since it was obtained imme- 

 diately before the restriction in diet. Using this value, we find that 

 the heat production per kilogram of body-weight per hour fell until 

 on January 28 it was 13.3 per cent lower than it was on January 6. 

 The heat production per square meter of body-surface per hour also 

 fell until on January 28 it was 17.1 per cent lower than on January 6. 

 With Squad A the computed heat values for the final experiment of 

 February 2-3 gave values which indicated that there had been a de- 

 crease of 19 per cent in the heat production per kilogram of body- 

 weight over the initial value found on September 29-30. For the heat 

 production per square meter of body-surface it was 23 per cent. These 

 findings with Squad B of 13.3 and 17.1 per cent, respectively, for the 

 same factors are not quite so large, but the loss in body-weight and 

 what is, we believe, of still more importance, the loss of body-nitrogen 

 was by no means so great as it was with Squad A. 



Using the normal values obtained with this squad in October, we 

 may compute the total decrease in the heat output as shown by the 

 value obtained on January 28. On this basis we find that there has 

 been a decrease in the heat production from October 7 to January 28 

 (including both the seasonal variation and the variation due to the 

 restricted diet) of 22.7 per cent, and on the basis of the heat per square 

 meter of body-surface 24.7 per cent. These values actually exceed 

 somewhat those found with Squad A. Had it not been for the series 

 of observations on Squad B with uncontrolled diet on November 3-4, 

 November 17-18, December 15-16, and January 5-6, these values 

 would have been extremely difficult to interpret. The difficulty of 

 applying an arbitrary base-line or an arbitrary so-called ''standard" 

 value to a series of experiments is apparent, even when group measure- 

 ments are made. 



The general picture of reduction, then, is approximately what would 

 be expected from the loss in body-weight and the loss in nitrogen with 

 Squad B as compared with Squad A. Both show pronounced altera- 

 tions of the basal metabolism as the result of the restricted diet. The 

 decrease is not only absolute but relative, being from 13 and 23 per cent 

 lower per kilogram of body-weight and from 17 and 25 per cent per 

 square meter of body-surface. 



GENERAL CONSIDERATION OF THE EFFECT OF REDUCED DIET ON BASAL 



METABOLISM. 



From the net calories required for maintenance at the lower weight 

 level, we inferred that the caloric requirement had been reduced very 

 considerably, i. e., from a net intake of not far from 3,100 or even more 

 calories to a net intake of 1,950 calories during the period of mainte- 



