Constancy of relative body weight in children.

The height and weight records of 404 schoolchildren at age 6 to 7 and at age 13 to 14 were analysed. Relative weight (i.e.% of ideal weight for height) of a child tended to change little over this period of 7 to 8 years of rapid growth. The correlation coefficient of relative weight for the group at the two ages was 0·81. In only 6% of the children did relative weight change more than 20% in either direction. This stability of relative body weight, despite the variations in environmental factors during school years, emphasizes the dominant role of genetic factors in the monitoring of body weight.