856 METABOLISM. 



According to VOIT the adipose tissue of the body acts like the food- 

 fat, and the protein-sparing effect of the former may be added to that of 

 the latter, so that a body rich in fat may not only remain in nitrogenous 

 equilibrium, but may even add to the store of body proteins, while in a 

 lean body with the same food containing the same amount of proteins 

 and fat there would be a loss of proteins. In a body rich in fat a greater 

 quantity of proteins is protected from metabolism by a certain quantity 

 of fat than in a lean body. 



Because of the sparing action of fats an animal to whose food fat is 

 added may, as is apparent from the table, increase its store of protein 

 with a quantity of meat which is insufficient to preserve nitrogenous 

 equilibrium. 



Like the fats the carbohydrates have a sparing action on the proteins. 

 By the addition of carbohydrates to the food carnivora not only 

 remain in nitrogenous equilibrium, but the same quantity of meat 

 which in itself is insufficient and which without carbohydrates would 

 cause a loss of weight in the body may with the addition of carbohydrates 

 produce a deposit of proteins. This is apparent from the following table. 1 



Food. Flesh. 



Meat. Fat. Sugar. Starch. Metabolized. On the Body. 



600 250 ... ... 558 - 58 * 



500 ... 300 ... 466 + 34 



500 ... 200 ... 505 - 5 



800 ... ... 250 745 + 55 



800 200 ... ... 773 + 27 



2000 ... ... 200-300 1792 +208 



2000 250 ... ... 1883 +117 



The sparing of protein by carbohydrates is greater, as shown by the 

 table, than by fats. According to VOIT the first is on an average 9 per 

 cent and the other 7 per cent of the administered protein without a pre- 

 vious addition of non-nitrogenous bodies. Increasing quantities of 

 carbohydrates in the food decrease the protein metabolism more regularly 

 and constantly than increasing quantities of fat. ATWATER and BENE- 

 DICT 2 also found that the carbohydrates had a somewhat greater sparing 

 action upon proteins than fats. 



Because of this great protein-sparing action of carbohydrates the her- 

 bivora, which as a rule partake of considerable quantities of carbohydrates, 

 assimilate proteins readily (VoiT) . 



The greater protein-sparing action of carbohydrates as compared with 

 that of the fats occurs, as shown by LANDERGREN, 3 to a still higher degree 

 with food poor in nitrogen or in nitrogen starvation, in which cases the 





1 Voit, ibid., page 143. 



2 See Ergebnisse der Physiologic, 3. 



3 1. c., Inaug.-Diss., and Skand. Arch. f. Physiol., 14. 



