METABOLISM 171 



is deposited and a smaller part oxidized than occurs in an 

 exclusive proteid diet. 



From what has thus far been said, it follows that the 

 various foodstuffs are not of the same value for the organism. 

 In general, the body has the tendency to be less sparing 

 with the proteids than with the fats and carbohydrates. 



It also appears that the body can maintain its equilibrium 

 by foodstuffs mixed in various proportions. The question 

 is, which is the most suitable mixture ? The most suitable, 

 or the rational diet for an adult man, is 100 g proteid, 60 g 

 fat, 400 g carbohydrates. These figures have been obtained 

 by various experiments in metabolism in men. From the 

 experiments it has been observed that the figures do not 

 differ to any large extent with the occupation and place of 

 dwelling of the subject experimented upon. 



If the 60 g of fat are changed, according to the law of 

 isodynamics, into carbohydrates, the proportion of proteids 

 and carbohydrates in the daily meal is as I : 5.5. 



If, in feeding, the object is not only to keep the body 

 weight constant but to increase either the flesh or the fat in 

 the body, more foodstuffs must be taken in. But to increase 

 either the body flesh or fat, it is not a matter of indifference 

 which foodstuff is increased. 



The laying up of flesh can only be produced by proteid 

 food ; for from fat and carbohydrates no flesh can be 

 formed. But, by increasing the proteids of a diet predomi- 

 nating in proteids, little flesh is laid up. For the laying up 

 of flesh the most suitable diet is a moderate amount of 

 proteids besides large quantities of fats and carbohydrates. 

 But if considerable flesh is to be laid up, other conditions 

 than the nature of tlie food play an important part. For 

 example, the laying up of flesh (muscles) is especially favored 

 by proper muscular exercise (training). 



Fattening of the body. The fat laid up by the body 

 originates from : 



(a) The fat in the food ; for if a fat containing specific 

 constituents (rape-seed containing erucic acid) normally not 



