952 NUTRITION AND HEAT REGULATION. 



AVERAGE DIETS AND THEIR HEAT VALUES. 



MOLESCHOTT. RANKE. VoiT. 



CALORIES. CALORIES. CALORIES. 



Protein 130 gms. ... 533 100 gms. ... 410 118 gms. ... 483 



Fats 40 " ... 372 100 " ... 930 56 ' ... 520 



Carbohydrates ... 550 " . . . 2275 240 ' . . . 984 500 ' . . . 2050 



2980 2324 3053 



FORSTER. ATWATER. 



CALORIES. CALORIES. 



Protein ...... 131 gms. ... 567 125 gms 512 



Fats 68 "... 632 125 " .... 1172 



Carbohydrates . . . 494 " . . -J.825 400 "... . 1640 



2024 3324 



The average heat value of these diets is equal to 2742 calories, 

 of which about 18 per cent, is furnished by the protein. Generally 

 speaking, it will be found that in the dietaries selected voluntarily 

 by mankind the protein furnishes from 15 to 20 per cent, of the 

 total heat value of the diet. According to some physiologists 

 this proportion is unnecessarily large and it might be reduced 

 to as little as 5 or 10 per cent. Whether or not such a change is 

 justified has already been discussed to some extent (p. 906). 

 Leaving aside this point, it is usually estimated in round num- 

 bers that the diet should furnish daily 2400 Calories for an in- 

 dividual weighing 60 kgms., when doing no muscular work, or 

 about 40 Calories per kgm. of body weight. It will be noticed 

 that in all cases the greatest portion of this energy is obtained 

 from the carbohydrate food, which, on account of its economy, 

 its abundance, and its ease of digestion and oxidation in the 

 body, constitutes the bulk of our diet. In cases of excessive 

 muscular work the food eaten may supply more than twice the 

 average heat value given above. Thus, Atwater and Sherman 

 estimate that in a six-day bicycle race by professionals the heat 

 value of the food for the different participants varied from 4770 

 to 6095 Calories. Chittenden, in the work previously referred 

 to,* has raised the question whether the heat value of the diet 

 ordinarily employed is unnecessarily high. In his own case he 

 found that the body could be well nourished on a diet contain- 

 ing a total heat value of only 1600 Calories or 28 Calories per kgm. 

 of body weight instead of 40 Calories. The diet in this case, 

 it will be remembered, contained only 36 to 40 gms. of protein 

 in place of the 100 to 130 gms. recommended in the diets mentioned 

 above. The question thus raised is one that must be decided by 

 actual experience, but from the numerous statistical and experi- 

 mental results now availablef it would appear, as has been stated 

 above, that the total energy necessary in a diet, estimated in 



* Chittenden, "Physiological Economy in Nutrition," 1905. 



* See especially the numerous Bulletins of the U. S. Department of 

 Agriculture, Nos. 28, 116, 129, 149, etc. 



