24-HOUR ENERGY REQUIREMENTS. 213 



out of the 24 hours, though in the remaining 6 hours the child may be 

 occupied in such vigorous muscular exercise as to require a very large 

 correction of these figures before the ultimate 24-hour computation 

 may even be approximated. 



To explain the extraordinary needs of growing children solely upon 

 the basis of activity is somewhat difficult. The activities are, it is 

 true, enormous. The food consumption is proportionately great. 

 The deposition of tissue must be provided for from the food intake, 

 and this, in turn, augmented above the true needs for simple physical 

 activity. In all probability a factor by no means to be neglected is 

 the stimulus to metabolism resulting from the ingestion of food. As 

 has been shown in the report of an earlier research 1 on mixed diets, 

 especially when large amounts of food are taken, approximately 6 per 

 cent of the total caloric intake is eliminated as extra heat, which has 

 been technically termed the "cost of digestion." 



The final computation of the total 24-hour food-needs or heat-output 

 of a growing active child will require considerable research. The heat- 

 output of children at play is entirely a matter of 'speculation. The 

 determination of such heat production is by no means a technical 

 impossibility; indeed, the large respiration chamber at the Nutrition 

 Laboratory is designedly constructed for the measurement of exactly 

 this type of group activities, and it is hoped that information on these 

 points may ultimately be secured. In any event, it is clear that the 

 caloric needs of growing children are very much greater than they are 

 commonly supposed to be. The lesson to be drawn from our observa- 

 tions on private-school children (see page 72) is that outdoor life and 

 physical activity contribute towards the development of a larger indi- 

 vidual, so far as height, i. e., skeletal growth, is concerned, with like- 

 wise a greater weight with children of the same age. But it is probable 

 that even these children, with superior surroundings and presumably 

 better medical examination, care, and dietetic supply, may advan- 

 tageously be supplied with larger amounts of food than they at present 

 take. One could infer, therefore, from these observations, that, 

 aside from the possibilities of digestive derangements, it would be 

 impossible to supply the growing child with an excessive amount of 

 food. Every effort may legitimately be expended to secure a maximum 

 skeletal growth and the development of children above so-called 

 average weight. We believe that our investigation shows clearly that 

 the average weight for children is distinctly below the ideal or physio- 

 logically desirable weight. 



1 Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 261, 1918, p. 341. 



