PREDICTION OF THE BASAL METABOLISM OF YOUTH. 187 



THE PREDICTION OF THE BASAL METABOLISM OF YOUTH.i 



In the last analysis, one of the most important factors in a metab- 

 olism study is the potentiality of drawing from the data a method 

 of predicting the unknown metabolism of a subject. The establish- 

 ment of a normal, when based upon unvarying laws of either physics 

 or chemistry, results in a standardization of values that makes possible 

 the immediate estimation of the probable resultant of any two or more 

 physical factors. In physiology the normal variation is so great as 

 absolutely to preclude a mathematically established standard without 

 deviations therefrom. On the assumption that the children in this 

 study were normal in the commonly accepted use of that word, we 

 do find, however, that the total metabolism follows a reasonably uni- 

 form curve in some of the relationships studied. 



While nearly all of our numerous charts show a wide scatter of 

 points, certain charts are characterized by a fairly close grouping of 

 points around the hypothetical line indicating the general trend. 

 These are specially the charts showing the total calories referred to 

 body-weight for both boys and girls (figs. 26 and 27, pages 140 and 142) 

 and the total calories referred to actually measured surfaces for both 

 boys and girls (figs. 38 and 39, pages 161 and 164). From these 

 curves it would appear that it is not impossible to predict with 

 reasonable accuracy the probable basal metabolism of a child when 

 either the weight or the measured body-surface is known. The body- 

 weight is very readily and frequently obtained, but the Du Bois 

 method of measuring the body-surface, while very specific and readily 

 acquired after a little careful consideration of the directions, never- 

 theless requires such an extensive series of measurements as to make 

 its general use impractical. 



In general, the grouping of the individual points about the curves 

 in figures 26, 27, 38, and 39 is often so seemingly compact as to suggest 

 that the curve sufficiently represents the general trend for it to serve 

 as a foundation for the prediction of the basal metabolism of unknown 

 subjects. Still, on closer inspection, the scatter of individual points 

 is noted to be considerable. One deceptive feature of these curves, 

 making an intelligent comparison with curves for adults difficult, is 

 the fact that the deviation from the general line varies greatly as to 

 its percentage value according to the weight of the individual or the 

 size of the surface area; consequently it is only with percentage 

 relationships that one may properly deal. 



From an inspection of the curves for calories referred to both surface 

 and weight, it is difficult to estimate with the eye as to which basis, 

 i. e., surface or weight, would give the better method for prediction, 

 although in the earlier consideration of these curves we noted that 



*A preliminary discussion of this point has recently appeared: Benedict, Proc. Nat. Acad. 

 Sci., 1920, 6, p. 7. 



