40 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



many of the factors. A greater reduction in weight would prolong the 

 experiment and require greater dietetic control; the amount of dis- 

 comfort might be taken as roughly proportional to the degree of loss. 



Previous experience with fasting men has shown that it is perfectly 

 safe and not productive of great discomfort to fast completely for 

 several days. While the loss of 10 per cent could be secured by com- 

 plete abstinence from food (judging from our experience with the man 

 fasting for 31 days this loss could be obtained in a period of complete 

 fasting of 14 days), it was recognized that it was impractical to ask a 

 group of men to sacrifice their entire time to a test of this kind and to 

 undergo a complete deprivation of food for 14 days. Consequently it 

 was considered best to produce the loss in weight by the administra- 

 tion of a diet so reduced that there would be each day material drafts 

 upon body fat. It was therefore tentatively proposed that the ingesta 

 should be approximately from 50 to 70 per cent of the actual food re- 

 quirements. 



After the reduction in body-weight of 10 per cent had been reached, 

 the basal ration was then to be supplemented in each case with suffi- 

 cient energy in food materials to hold the body-weight at the lower 

 level and an attempt made to obtain nitrogen equilibrium as soon as 

 possible. Carbon equilibrium or energy equilibrium would be indi- 

 cated by constant body-weight over a period of weeks; nitrogen equi- 

 librium would be shown in the usual manner by the balance between 

 the nitrogen in the intake of food and the nitrogen in the feces and 

 urine. 



From our experience with fasting men and from the experience of 

 this Laboratory in conjunction with Dr. E. P. JosHn in studies of dia- 

 betics with their extreme losses, it appeared perfectly safe to attempt an 

 observation of this kind, since the reduction in body-weight was to be 

 but 10 per cent or slightly more. 



SELECTION OF SUBJECTS. 



For the study of so important a problem as the influence of under- 

 nutrition upon basal metabolism and vital processes in general, it was 

 essential that the subjects of the research should be men rather than 

 animals, especially as the nation is not so much interested in the better 

 utihzation of feeding stuffs for animals as it is in the utilization of 

 food for man. This naturally increased our responsibility and finan- 

 cial obligations, as only those having actual experience with this type 

 of work can realize. Investigators who work entirely with small ani- 

 mals and domestic fowl can have little conception of the perplexities 

 which arise in working with a considerable number of adults. 



Observations on one man may be considered in general as typical of 

 observations on men as a whole until striking abnormalities or varia- 

 tions are shown. Thus the ingestion of 100 grams of sugar produces a 



