BASAL METABOLISM. 71 



basal metabolism begin (approximately 12 hours after the iugestion of 

 food) , active digestion has ordinarily ceased and the body deposits are 

 presumably still in a normal condition, with the usual liberal supplies 

 of glycogen, fat, and protein. During the post-absorptive condition 

 the body begins to draw upon these deposits, particularly the glycogen, 

 and in approximately 2 to 4 days of fasting the labile glycogen supply 

 is heavily depleted; thereafter the metabolism remains essentially a 

 protein-fat katabolism until food is again taken. As a result of these 

 heavy drafts upon body material during fasting, we have, after one or 

 two days of fast, a condition which represents at least the beginning 

 of inanition. It would appear, therefore, that as soon as the general 

 nutritive condition of the body is seriously affected by a disturbance 

 in the proportion of body materials, we pass outside the field of measure- 

 ment of the basal metabolism for studies on the influence of food. 

 It is well known that one of the first effects of the ingestion of food after 

 long inanition is the replenishment of the reserves of body material, and 

 there is excellent evidence that this replenishment is accomplished by 

 processes materially different from those occurring during ordinary 

 digestion. 



For the majority of experiments in which the effect of food is studied, 

 a sharp differentiation between the post-absorptive condition and the 

 beginning of inanition is unnecessary, but in certain of our experiments, 

 especially those made in 24-hour periods, when the ingestion of food 

 was 24, 36, 48, or even 60 and more hours after the last meal, we may 

 have a condition of the body which distinctly approximates the first 

 stages of inanition. The increment due to the ingestion of food would 

 therefore be based upon abnormal values which would theoretically be 

 somewhat lower than those ordinarily used for such studies. With so 

 low a basal value, it frequently occurs that the stimulus of food simply 

 compensates for the depressing influence of the previous fast and no 

 increment in the metabolism is found. The effect obtained from the 

 ingestion of food thus becomes a function of the duration of the fasting. 

 For this reason the series of experiments in which the period of fasting 

 was limited to two days are logically more satisfactory than those in 

 which the subject fasted for a longer period. 



The greatest practical difficulty encountered in the use of the 24-hour 

 method of experimenting was the fact that after one or two days of 

 fasting the subjects were frequently unable to eat appreciable quanti- 

 ties of food without distress. In the series of 2-day fasting experi- 

 ments with college students at Wesley an University, the experimental 

 plan included the ingestion of unusually large amounts of food on the 

 third day for the purpose of obtaining maximum effects. To our 

 surprise and disappointment, it was found in many cases that the sub- 

 jects could not eat large amounts of the food, or, having eaten it, they 

 experienced distress, this being particularly true when large quantities 



