62 



because none of them apparently had as nmch exercise as mechanics 

 and others engaged in various forms of muscular work, who are 

 included in the group covered b}^ the term "light to moderate mus- 

 cular work." For all the subjects together the average daily con- 

 sumption of digestible protein was 78 grams and the available energy 

 of the food 2,720 calories, whereas the standard with which comparison 

 has been made — namely, that for a man with sedentary occupation — 

 suggests 92 grams digestible protein and 2,700 calories of available 

 energy. In other words, as shown by this comparison, the average 

 amount of digestible protein of the daily diet was less than the stand- 

 ard selected calls for, while the amount of available energy was about 

 the same. 



It is interesting, however, to consider the amount of digestible pro- 

 tein and available energy supplied by the food in comparison witli the 

 weights of the subjects. Assuming that the average American man 

 weighs not far from 150 pounds (68 kilograms), the commonly accepted 

 dietar}^ standard for the average man at sedentary employment would, 

 therefore, provide lA grams protein and 40 calories of energy per 

 kilogram body weight. As shown by the average results of all the 

 students, the food furnished 1.3 grams digestible protein and 45 calories 

 of energy per kilogram body weight, or 7 per cent less protein and 12 

 per cent more energy than is called for by the standard selected for 

 comparison. In the case of the individual studies with one exception 

 the amount of energy provided was greater than the standard calls for, 

 while with live of the subjects the amount of protein equaled or exceeded 

 the standard and with four it was only a little below it. It will be seen 

 that when the comparison is made on the basis of actual weight of the 

 subjects the agreement with the dietary standard is closer than on the 

 basis of amounts per person per day. 



As has been stated, marked differences were observed in the amounts 

 consumed by the different individuals and by the same individual in 

 different periods, j^et on the whole the subjects appeared to be in 

 equilibrium with their environment. The question naturally arises 

 then, what would be a suitable dietary standard for these men, since 

 in some cases there appears to have been for a given subject not one 

 ration only but several different rations which enabled him to do his 

 customary work without apparent change in physical condition? It 

 seems reasonably certain that as regards protein the daily requirement 

 is not a fixed quantity either for different individuals under similar 

 circumstances or for the same individual at all times. So far as any 

 given individual is concerned, it is known that the quantity of protein 

 may vary within rather wide limits and that the body seems capable of 

 adapting itself under certain conditions to diets of markedly different 

 character. When such facts are considered the variations in the 

 amounts of protein in the diets of the different subjects or with the 

 same subject in different periods are not surprising. 



