DIETETICS. 941 



justified has already been discussed to some extent (p. 898). 

 Leaving aside this point, it is usually estimated in round numbers 

 that the diet should furnish daily 2400 Calories for an individual 

 weighing 60 kgms., 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 re- 

 ferred 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 con- 

 taining 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 

 terms of its heat value, varies chiefly with the amount of muscular 

 work to be done. Persons who lead a very muscular life require 

 a correspondingly large amount of energy in the diet, and this 

 demand is met usually by augmenting the proportion of carbo- 

 hydrate and fat, especially the carbohydrate. Since the amount 

 of protein is not varied greatly in such cases the diet is relatively 

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

 life, including, broadly speaking, all the well-to-do class, require 

 less energy in their diet, and they can afford to reduce the pro- 

 portion of carbohydrate and fat. The diet in such cases may be 

 relatively rich in protein, although the amount per kilogram of 

 body weight is not increased, in fact, is usually diminished some- 

 what. These facts are illustrated in Atwater's estimate of the 

 diet necessary for men performing different amounts of muscular 

 work. 



PROTEIN. CARBOHYDRATE 

 AND FAT. 



Man doing hard muscular work .600 cal. 3550 cal. 



Man doing moderate muscular work 500 " 2900 " 



Man doing no muscular work 360 " 2040 " 



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

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

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



