482 SYMPOSIUM ON FOOD PROBLEMS 



At the start we were confronted with the possibihty of a seasonal 

 variation. Thus, if one took a group of twelve active Y. M. C. A. 

 students, at the end of a summer vacation, fresh from summer 

 camps with their outdoor activties, and placed them in academic halls 

 with restricted hours, artificial illumination, and curtailed physical 

 activity, it is conceivable that there would be a normal retardation of 

 metabolism in the later fall months. To insure a suitable base line, 

 therefore, a second group of twelve men from the large number of 

 volunteers originally presenting themselves were selected to act as 

 a control squad. These men were in every particular studied with 

 the same degree of care as Squad A, except that there was no dietetic 

 control. 



While body-weight can be taken as an approximate index of the 

 metabolic level, further checks were absolutely necessary to rule out 

 the inevitable difference in muscular activity that would be found 

 with groups of individuals, even when they were subsisting under 

 the same collegiate conditions. The gaseous metabolism was there- 

 fore measured practically every morning for each one of the first 

 squad. These measurements were made by collecting the expired 

 air and analyzing it. From the amounts of oxygen consumed and 

 carbon dioxide produced the basal heat output could be computed by 

 indirect calorimetry, thus furnishing the second index of metabolic 

 level. The pulse rate was recorded simultaneously every morning. 

 Every other Saturday night the entire group of men were taken to 

 Boston and placed inside a large respiration chamber, where they 

 could sleep comfortably. The carbon-dioxide excretion of the 

 twelve men was thus determined simultaneously during deep sleep. 

 This furnished a third criterion for judging the metabolic level. 



The control squad showed no seasonal variation and their basal 

 metabolism, as measured in the large respiration chamber in Boston, 

 was found to be absolutely identical with that of the first group of 

 twelve men prior to the restriction in diet. To check the important 

 findings with the first squad during the early period of the investi- 

 gation, the second squad was later placed upon a very restricted diet 

 for a period of three weeks, the diet given being less than one half 

 of their normal requirements. 



For both squads, when on diet, the food for each day was care- 



