THE METABOLISM OF FAT DURING FASTING 287 



proteid katabolised. During moderate muscular work the proteid 

 metabolism is scarcely affected, and thus the respiratory quotient 

 will indicate whether the additional matter oxidised is fat, or 

 carbohydrate, or both. 



The method of computation is illustrated by the following 

 example : 



In a dog one kg. metre of work increased the 2 use (per kg. 

 body weight) by 1-6704 c.c. ; the C0 2 output by 1-4670 c.c. ; the 

 respiratory quotient = '8 7 8. 



Now let x = amount of 2 consumed in the oxidation of fat, 

 and 1-6704 x the amount consumed in the oxidation of carbo- 

 hydrate. Since the R. Q. of fat is 0*7069, x c.c. 2 would yield 

 0.7069 x c.c. C0 2 , and since the R. Q. o.f carbohydrate is 1-0, 

 the 1*6704 x c.c. of 2 used to oxidise carbohydrate would yield 

 1-6704-a: c.c. C0 2 . Therefore 0-7069 x + (l-6704-x) = 1-4670, 

 and x = 0-6939. 



Thus the oxygen consumed in the oxidation of fat was 

 0-6399 c.c.,and by carbohydrate 1-6704 -0-6399 = 0^765 c.c., and 

 the C0 2 produced by fat was 0-4905 c.c., and by carbohydrate 

 0-9765 c.c. 



From these data the actual amount of fat and carbohydrate 

 metabolised can be computed, as 1 grm. fat requires 2*8875 grm. 

 or 2*028 litres of oxygen for its oxidation, and produces 

 1-434 1. C0 2 , while 1 grm. carbohydrate requires 1*185 grm. or 

 0-832 litre 2 and produces 0-832 1. C0 2 . 



THE METABOLISM OF FAT DURING FASTING 



As soon as the influence of the food previously taken has passed 

 away, the body settles down to a steady level of fasting meta- 

 bolism, and the expenditure both of proteid and fat shows only 

 slight variations for many days. 



