22 



Metabolism of Healthy Man. 



part of undigested material has been radically revised in the past 10 years, 

 there still remains the fact that the material in the feces can be considered as 

 not available to the body and as an excretion. It was impracticable in this 

 experiment of only 24 hours' duration to separate the feces. From a large 

 number of experiments made with a simple diet like that partaken of in this 

 experiment it has been found that not far from 93 per cent of the protein, 97 

 per cent of the fat, and 98 per cent of the carbohydrates is absorbed. If, there- 

 fore, allowance is here made for the amounts determined in a normal excretion 

 of feces, the apparent gain of protein will probably become a loss, the loss 

 of fat will be somewhat greater than here indicated, and the apparent gain of 

 carbohydrates will be slightly less. 



Table 8. Gain or loss of body material 

 Metabolism experiment No. 101. 



1 N X 6.25. 



2 Assumes carbohydrate katabolized to be same in 

 amount as carbohydrates absorbed less 21 grams of 

 glycogen stored. 



Transformation of Energy. 

 Heat production. The energy of the material katabolized in the body may 

 be computed directly from the measurements of the katabolism and the well- 

 known factors which represent the heat of combustion of the protein, fat, and 

 carbohydrate. The calculation, then, may be expressed thus: 



Calories. 



Protein 38.7 X 5.65 = 219 



Pat 96.7X9.54 = 923 



Carbohydrate 217.7 X 4.19 = 912 



The total potential energy of material katabolized in the body was therefore 

 2054 calories. Of this a certain portion, however, was not actually trans- 

 formed into heat for the actual determination of the potential energy of the 

 urine showed that there was unoxidized material in the urine equivalent to 

 62 calories. Therefore, the actual energy transformation resulting from the 

 katabolism of material in the body was 1992 calories, and this represents very 

 nearly the total heat production for the day for this subject. 



Balance of intake and output of energy.- -The potential energy of the food, 

 making no allowance for feces, was 1496 calories, and hence there was a demand 

 upon body-fat for energy to supply the necessary amount for the day. The 

 large number of assumptions made necessary by the deficient data of this ex- 

 periment do not warrant further refinements, but in general terms it may be 

 said that there was a draft upon the body for sufficient material (fat) to supply 

 the deficiency in available energy of the food amounting in round numbers 

 to 550 calories. 



