106 



METABOLISM AND NUTRITION 



creta, and determined directly from calorimetric measurement of the heat 

 given off by the subject of the experiment. In all the experiments carbo- 

 hydrates were given in fairly large quantities and in the calculation of the 

 heat values it was presumed, in conformity with the current view, that they 

 were burned first. Now the experiments actually show a very close agree- 

 ment between the calculated and the observed heat production. From which 

 it follows that the theoretical presumption is a correct one, and that the total 

 quantity of carbohydrates absorbed is burned before the body fat. 



Especially instructive are two series of experiments in which both the total 

 calories supplied (2,490 and 2,489 respectively) and the quantity of proteid 

 were the same, but where the proportion of fat to carbohydrates was consider- 

 ably different in the two. In the one experiment 94.8 g. fat -)- 247.2 g. carbo- 

 hydrates were administered, in the other 40.3 g. fat + 375.2 g. carbohydrates. 

 Direct calorimetric determination of the heat production yielded in the first 

 2,085 Cal., in the second 2,079 Cal., showing that the ratio of carbohydrates to 

 fats within these limits at least is a matter of indifference to the organism. 



Let us see now in which direction the addition of carbohydrates will 

 influence the total metabolism. 



Experiments of Pettenkoffer and Voit along this line gave the following 

 results : 



From Experiments 1 and 2 it appears that the total metabolism after 

 ingestion of carbohydrates (and a little fat) is not greater than it is in 

 starvation, that carbohydrates therefore can completely replace the fat de- 

 stroyed in starvation. From the series with 500 g. meat (17 g. N) no influ- 

 ence of the carbohydrates on the total metabolism is indicated. With 1,500 

 g. of meat addition of 172 g. carbohydrates produces only a slight increase 

 (less than ten per cent), with 1,800 g. meat, 379 g. carbohydrates produce 

 no increase at all. 



1 A sign means that fat has been stored in the body. 



2 1 g. N = 26.0 (25.98) Cal., 1 g. fat = 9.46 Cal., 1 g. carbohydrate = 4.1 Cal. 



