FATS, CARBOHYDRATES, AND ALBUMINS. 



339 



previous " rest " experiment. This amount of albumin, with small quan- 

 tities of fat and carbohydrate, was the starting ration of the " work " 

 experiment. In the principal test, in one case a considerable amount of 

 fat (butter, cream) was added, while in another experiment an equivalent 

 amount of carbohydrate (milk-sugar and cane-sugar) was employed. The 

 total energies received was somewhat less than the organism required; that 

 is, some of the body substance was attacked. These experiments estab- 

 lished the values of fats and carbohydrates as sources of muscular energy 

 in two directions. In both cases the energy in the form of albumin and the 

 total energy received were the same, the only differences being the predomi- 

 nance of fat in the one case, and of carbohydrates in the other. The 

 external work was likewise the same in both cases. If the total energy 

 utilized for the production of a definite amount of work was the same for 

 a fat as for a carbohydrate diet, the fact would be established that fats 

 and carbohydrates have the same value as a source of muscular energy. 

 In the next place the amount of energy abstracted from the body itself 

 the quantity of energy received in the food was, as already stated, not 

 quite enough to satisfy the requirements must be a measure of the 

 relative value of a diet in which either fat or carbohydrate predominates. 

 If equal quantities of body substance were used up in both cases, we 

 would have a further support of the equality of carbohydrates and fats 

 as sources of muscular energy. The following table will give us an idea 

 of the results obtained by Atwater in his experiments. 



RELATIVE VALUES OF FATS AND CARBOHYDRATES IN THE FOOD 

 FOR THE PERFORMANCE OF MUSCULAR WORK. 



