878 METABOLISM. 



It is certainly true that the amount of nutriment required by the body 

 is not directly proportional to the body weight, for a small body consumes 

 relatively more substance than a larger one, and varying quantities of 

 fat may also cause a difference; but a large body, which must maintain 

 a greater quantity, consumes an absolutely greater amount of substance 

 than a small one, and in estimating the nutritive need one must also 

 always consider the weight of the body. According to VOIT, the diet 

 for a laborer with 70 kilos body weight requires 40 calories for each kilo. 

 EKHOLM 1 calculates, basing it upon his experiments, that for a man 

 weighing 70 kilos, busied with reading and writing, the net calories are 

 2450 and the gross calories 2700, or 35 and 38.6 calories per kilo. In the 

 ordinary sense for a resting man the general food requirement is calculated 

 in round numbers as 30 calories for every kilo. The minimum figure 

 for metabolism during sleep and in as complete rest as possible has been 

 found by SONDEN, TIGERSTEDT and JOHANSSON 2 to be 24-25 calories. 



As several times stated above, the demands of the body for nourish- 

 ment vary with different conditions of the body. Among these condi- 

 tions two are especially important, namely, work and rest. 



In a previous chapter, in which muscular labor was spoken of, it was 

 seen that all foodstuffs have almost the same power of serving as a source 

 of muscular work, and that the muscles, it seems, select that foodstuff 

 which is supplied to them in the greatest quantity. As a natural sequence 

 it is to be expected that muscular activity requires indeed an increased 

 supply of foodstuffs, but no essential change in their relation as compared 

 to rest. 



Still this does not seem to hold true in daily experience. It is a well- 

 known fact that hard-working individuals men and animals require 

 a greater quantity of proteins in the food than less active ones. This 

 contradiction is, however, only apparent, and it depends, as VOIT has 

 shown, upon the fact that individuals used to violent work are more 

 muscular. For this reason a person performing severe muscular labor 

 requires food containing a larger proportion of proteins than an individual 

 whose occupation demands less violent exertion. Another fact is that 

 the diet rich in proteins is often concentrated and less bulky, and also 

 that in many cases of training a diet containing as little fat as possible 

 is selected. 



If we compare the results for the needs of food in work and rest which 

 are obtained under conditions which can be readily controlled, it is found 

 that the above statements are in general confirmed. As example of this 



1 Skand. Arch. f. Physiol., 11. 



2 Sonden and Tigerstedt, Skand. Arch, f . Physiol., 6; Johansson, ibid., 7; Tigerstedt, 

 Nord. Med. Arkiv. Festband, 1897. 



