944 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 " ... o20 



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



2980 2324 3053 



FOR.STER. AtWATER. 



Calories. Calories. 



Protein 131 gms. ... 567 125 gms 512 



Fats 08 "... 632 125 "... - 1172 



Carbohydrates . . 494 " ... J825 400 " .... 1640 



2024 3324 



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

 ei 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. 896). 

 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. (See also p. 957 for 

 reference to basal metabolism.) 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 abun- 

 dance, and its ease of digestion and oxidation in the body, con- 

 stitutes 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. 

 Experiments* and observations have shown clearly that the total 

 energy necessary in a diet, estimated in terms of its heat value, 

 varies chiefly with the amount of muscular work to be done. 

 Persons who lead a very muscular hfe require a correspond- 

 ingly large amount of energy in the diet, and this demand is 

 met usually by augmenting the proportion of carbohydrate and 

 fat, especially the carbohydrate. Since the amount of pro- 

 tein is not varied greatly in such cases the diet is relatively poor 

 in this foodstuff. On the contrary, those who lead a sedentary 



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

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



