INGESTION OF MIXED DIETS. 325 



value obtained by averaging all of the fasting days, as the basal value 

 may change and in certain circumstances does change considerably 

 during the fast. This was shown clearly in the fasting experiment of 

 31 days carried out in the Nutrition Laboratory. 1 



It hardly seems justifiable to attempt a computation of the fasting 

 values obtained in these four experiments on the basis of per kilogram 

 of body-weight or per square meter of body-surface. There were, to be 

 sure, measurable losses in weight which were probably largely due to a 

 loss of water from the body, especially in the earlier part of the fast. 

 That there was a considerable loss in body-surface or of active heat- 

 producing organized tissue is hardly conceivable. After the ingestion 

 of food there were undoubtedly slight gains and losses in weight, but 

 this discussion considers the organism as a whole, for only days with and 

 without food are compared and no attempt is made to compare results 

 obtained with different individuals. 



Even in the first experiment recorded in table 248 (that with A. L. L.) 

 the actual value of the base-line may be seriously questioned. An 

 average value for the fasting periods would be not far from 2,025 calo- 

 ries. On this basis it can be seen that the ingestion of food, with a fuel 

 value of 2,502 calories, barely increases the metabolism on the first day, 

 increases it noticeably on the second, and produces a very pronounced 

 increase on the third. 



In the first experiment with S. A.B., the ingestion of food, with a fuel 

 value essentially that of maintenance during fasting, resulted in a 

 slight increase in the metabolism on the first food day over the metab- 

 olism on the fourth fasting day. If, however, the average of the fasting 

 days is taken as an absolute value, it will be seen that the ingestion of 

 food simply checked the progressive decrease in the metabolism. 

 Here again the uncertainty of the base-line is noticeable. 



In the second experiment with S. A. B., the ingestion of food with a 

 fuel value considerably above the 24-hour maintenance requirement 

 (over 500 calories above the final fasting-level) resulted in an increase in 

 heat production of a little over 100 calories, while in the last experiment 

 with S. A. B. the ingestion of food with a fuel value about 200 calories 

 higher than the heat production on the sixth and seventh fasting days 

 resulted in an increase in the metabolism of approximately 200 calories, 

 the daily metabolism on the food days being almost exactly equal to the 

 fuel value of the intake. 2 



From this varied picture of the influence of food ingestion upon 

 metabolism following fasting, certain rather clear conclusions may be 

 drawn. First, in all instances food produced an increased metabolism 



'Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 372. 



2 Grafe (Deutsch. Arch. f. klin. Med., 1913-14, 113, p. 1), comparing results obtained in a 



prolonged fast with those obtained with a diet of almost pure carbohydrates, found no 



rise in the metabolism after food. 



