402 THE SCIENTIFIC MONTHLY 



This brief outline may serve as an introduction to some of 

 the problems which require consideration in the establishment 

 of normal standards for work in human nutrition. 



It would be quite unfair to leave the reader with the im 

 pression that the basal metabolism is a fixed and unchangeable 

 physiological constant. While extremely valuable as a basis of 

 comparison, the basal metabolism is subject, not only to great 

 variation from individual to individual, but to modification in 

 response to profound experimentally induced changes in the 

 level of nutrition of the subject. Thus a man who underwent 

 a 31-day fast at the Nutrition Laboratory, during which he 

 took no food whatever and only about 900 cubic centimeters of 

 distilled water per day showed a decrease of 28 per cent, in 

 his basal metabolism. 



A more recent investigation of the influence of severely 

 limited diet, undertaken by the Nutrition Laboratory on squads 

 of men who volunteered for this purpose at the International 

 Y. M. C. A. College at Springfield, Mass., in response to the 

 need for more exact information concerning the influence of 

 war-time diet on health and efficiency, has shown a striking 

 influence of reduced diet accompanied by rapid alteration of 

 body weight on the basal metabolism. One squad was kept for 

 a period of four months on a restricted diet with an energy con 

 tent of one half to two thirds of the requirements prior to the 

 fast, when the normal demand of the men ranged from 3,200 

 to 3,600 net calories. After a reduction of only 12 per cent, 

 in weight, 1,950 calories only were required to maintain this 

 weight. 



Notwithstanding this fact, and the wide variability in basal 

 metabolism in whatever units it may be expressed, the basal 

 metabolism when measured on large numbers of individuals in 

 good health and living under normal conditions, and described 

 in terms of the proper biometric constants and equations, fur 

 nishes a valuable, and as yet the only available, standard of 

 comparison in the investigation of all the special problems of 

 energy requirements in human nutrition. 





