356 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



NITROGEN OUTPUT OF SQUAD A AT LOW WEIGHT-LEVEL. 



The average nitrogen excretion of Squad A from December 3 to the 

 end of the experiment was 10.5 grams. (See table 73.) This probably 

 represents on the whole the most constant period of lower weight dur- 

 ing the experiment, although the second part of this period is compli- 

 cated by the abnormal rises in weight incident to the Christmas vaca- 

 tion. We may take this nitrogen value, therefore, as an approximate 

 indication of the level of nitrogen upon which these men were capable 

 of living with their lowered intake. 



A comparison of the nitrogen excretions in the urine at these dif- 

 ferent weight-levels is of great significance as indicating the possibility 

 of a material reduction of protein in the diet, protein being one of the 

 most costly food constituents. After the extensive experience of 

 Professor Chittenden, and more particularly the recent compulsory 

 experience of the Central Powers, any real danger from a reduction of 

 protein in the intake seems to be lacking. It was emphasized at the 

 outset that we did not intend to complicate our problem by control 

 of the protein intake. We were not advocating either a high or a low 

 protein diet or a vegetarian or mixed diet. We were confessedly 

 somewhat surprised at the conclusion of the research to find that the 

 nitrogen excretion, especially at the lower weight-level, and with a 

 material reduction in the caloric intake still remained so high, for we 

 had expected it to be somewhat lower. The fact that this did not 

 come to our attention until some time after the experiment ceased 

 shows the complete objectivity of our method of weight reduction and 

 food control. The criterion as to food allotment was, in every in- 

 stance, the actual weight of the subject. Since the exact knowledge of 

 the intake of nitrogen and energy depends upon chemical analysis and 

 determination of the heat of combustion, the actual ingestion of energy 

 and nitrogen per day could only be computed several weeks later. 

 This in part accounts for the noticeable variations in the intake of 

 energy and nitrogen frequently appearing in the tables. 



We have no reason to believe that a somewhat lower protein level 

 might not have readily been obtained without a correspondingly great 

 increase in calories. This, however, remains a disputed point. The 

 fact that nitrogen equilibrium, or at least an indication of nitrogen 

 equilibrium in the frequent appearance of plus values at the lower 

 weight-level, was obtained with the surprisingly low caloric intake of 

 1,950 calories is, we believe, a new feature. It has been supposed 

 from earlier feeding experiments that no material reduction in the 

 nitrogen excretion can be maintained without very considerably 

 increasing rather than decreasing the calories. Professor Chittenden, 

 without absolute caloric dietetic control, showed that his soldiers 

 were able to subsist with a low nitrogen output with no great incre- 

 ment in calories. Indeed, his evidence strongly suggested lowered 

 calories. This research fully confirms his inferences with regard to 

 this point. 



