DISCUSSION OF RESULTS. 



93 



INFLUENCE OF THE CHARACTER OF DIET ON THE HEAT-OUTPUT PER UNIT 



OF WORK. 



While from the general observations of the metabolism with and 

 without food the inference was properly drawn that there was no 

 material increase in the heat-output per unit of work in the food 

 periods, nevertheless certain of the experiments permit a more detailed 

 examination of this point since a reasonably satisfactory grouping of 

 the results may be made upon the basis of the character of the diet. 

 The experimental plan as originally outlined called for a series of 

 walking experiments at each of the three standard speeds with diets 

 containing a preponderance of each of the three principal nutrients. 



The average figures representing the heat per unit of work with the 

 three diets and the three speeds are collected in table 17. In this table 

 the average speed for the different groups is given, as the speed per 

 minute, especially with the low speed, was not exactly the same for the 

 three diets. Only the walking experiments are considered in this 

 connection, none of the running experiments being included. 



TABLE 17 Influen: 



~4 character of diet on the heat-output per horizontal kilogrammeter during 

 walking experiments with subject II. 



Aside from the generally increasing value of the heat per unit of 

 work as the speed increases, which is clearly shown in table 17, we 

 note, in comparing the values obtained with the different diets, a dis- 

 tinctly higher, although not striking, increase in the heat per unit of 

 work with the protein diet as compared with the carbohydrate diet, 

 this increase being approximately 9 per cent at the low speed and 3 per 

 cent at the moderate and high speeds. With the fat diet the com- 

 parison was made only with the low speed, and we find that the heat- 

 output per unit of work was essentially the same as that with the car- 

 bohydrate diet and measurably less than was obtained with the protein 

 diet. The general impression derived from the comparison of all the 

 experiments with subjects I and II was that the heat per unit of work 

 was practically independent of the taking of food. It appears from the 

 foregoing discussion, however, that this conclusion should be slightly 

 modified when diets containing large quantities of protein are con- 

 sidered, for the data in table 17 indicate that with such a diet a slightly 

 higher heat-output per unit of work may be expected. 



