The association of weight, weight variability and socioeconomic situation among children

We studied the association of body weight and weight variability among populations from different geographic, historic and socioeconomic background.

We reanalyzed data from 833 growth studies of 78 different countries from 1920 to 2013. We used data from two age groups-infants (age 2 years) and juvenile (age 7 years)-and divided the studies into two geographic-socioeconomic groups.

Multiple regressions showed significant interactions between weight, sex, historic year of study, continent and within-study standard deviation. Multiple regression revealed R(2)=0.256 (P<0.001) at age 2 years and R(2)=0.478 (P<0.001) at age 7 years. Although infants and juveniles in more affluent countries are heavier than children in less affluent countries (P<0.001), the within-study standard deviation of the two geographic-socioeconomic groups differs at age 7 years (P<0.001) but not at age 2 years (P>0.15).

The general impression that prosperous conditions lead to growth improvements in height and weight appears to be true only at a large scale: wealthy countries have tall and heavy children. At small scale, the situation is different. Whereas economic and nutritional improvements can exhibit substantial effects in weight gains, the discrepancy between the within-population variation in height and weight strongly suggests that height gains and weight gains are subject to different regulations.