Relationship between height and weight

From the foregoing discussion it is obvious that an index of the state of nutrition based on the relationships of height to age and weight to age is subject to very considerable error, because although a child may be of normally short stature with an accompanying small bodyweight, due to racial characteristics, on the basis of age he would be considered to be both underheight and underweight. If the short stature is due to racial characteristics and not to deficiency in the growth-promoting factors in the diet, the child may still be considered normal, indeed may be considered ideal. Before this condition can be established, however, a far greater study of the height-weight ratio of children of normally short parents should be made, and in considering the average mixed population of American schools the element of racial characteristics must not be overlooked.

Having shown that neither an average height for age nor an average weight for age is best suited for an index of nutritional state, since the height may be accompanied by varying weights and vice versa, it is clear that as an index of the best proportional distribution of flesh to skeleton the relationship between height and weight is most satisfactory. For a child of a given height a definite weight is productive of a fullness of development and addition of flesh that may be termed ideal. When the child has too little flesh it is very obvious, and likewise when it has too much flesh. The problem then arises as to what is the best proportion between weight and height for children. Should children be somewhat light in build or distinctly overweight, as judged by the popular conception of underweight and overweight when applied to children? Referring again to our private-school data, we find that although these children are heavier and taller than other series of normal children at the same age, when the height and weight are compared they are on the whole somewhat thinner for their height than are our normal laboratory children selected for this study. On the basis only of weight referred to height, therefore, it would appear as if our laboratory children had somewhat the advantage over the group of private-school children, i. e., so far as proportion is concerned. It still remains a fact, however, that had our laboratory children been given the advantages of private-school children, namely, outdoor life, better medical care, operative treatment if needed, and better diet, particularly with regard to growthpromoting factors, the skeletal growth would probably have been greater than actually noted.

The question is a serious one, then, as to whether we should consider a child of a certain age who has a large proportion of flesh for his height a better nourished child than one of the same age who is taller and at the same time heavier, but in whom the proportion between weight and height is not so great as with the shorter child. This question leads us to a consideration of the importance of the diet factors which play a rôle in growth. No one would seek for abnormal rapidity in the growth of children. In the normal development of the child growth proceeds with a considerable degree of regularity and, on the average, at a certain rate of rapidity. When children, however, are subjected to ideal outdoor life, with plenty of food and excellent medical care, they do grow -- in skeletal form, at least, as well as in total weight -- at a somewhat greater rate than otherwise. Is this desirable or not? Everything points to the desirability of this condition, and yet on close analysis it is seen that these private-school children do not have the proportion of weight to height found with the group of laboratory children selected for our measurements. Which, therefore, of the two factors is the most important in the process of growth, height or weight? The striking difference between the private-school children and our laboratory children is the greater height and correspondingly greater weight of the former, although the weight is in all probability simply a natural concomitant of the height. The fact that the obviously ideal conditions of private-school life result in this increased growth would seem to be prima facie evidence of its desirability. On the other hand, we must consider for a moment the relationship between weight and height which has resulted, with our laboratory children at least, in a better proportionment -- that is, these children are somewhat heavier for a given height than are the private-school children.

The underweight child is a great care to nutritional experts, and so the greatest stress is laid upon the question of underweight, and apparently little, if any, attention is given to underheight. We have pointed out that underheight may be due to erroneous dietary conditions, although in many instances such conditions are perhaps entirely unsuspected. But the chief attention of all dietitians and pediatricians is given to the underweight of the child; hence, the stress laid upon the larger proportion of weight for height. The desirability of advocating this proportion is well substantiated by the importance ascribed to the relationship between weight and height in the best and recent studies of vital statistics. These statistics show clearly that longevity is better favored in youthful adults, particularly under 30 years of age, if there is a certain degree of overweight; that is, that those youths over the average weight usually have a somewhat better expectancy of life. Beyond the age of 35 years statistics show that a weight somewhat under the average insures a better life expectancy. If during the period of early adult age, longevity is favored by having the weight somewhat above the average, it seems a reasonable conclusion that this same condition must be advantageous for children. Consequently we believe that during the entire period of growth the weight should, if possible, be somewhat over the average and should approach the ideal as indicated by the weight for ages of our privateschool children. Indeed, it seems logical to assume that if the privateschool children had been supplied with a larger amount of food, so that they could have put on more flesh and had a proportion of weight to height more nearly in accord with that found with our laboratory children, they would have presented an even more ideal picture. Apparently they were slightly underweight for their height, while our laboratory children, selected from by no means as good an environment, showed a somewhat better proportion of weight to heightbetter when judged on the basis that excess weight is advantageous during the period of growth. For these reasons we believe that all curves which represent a so-called normal, either for height or for weight, are drawn at too low a level, and instead of using the average for normal, as is commonly done, a value perceptibly higher than the average should be striven for in establishing any standards to represent the ideal rates of growth in height and weight for the various ages.