A prospective study of body image dissatisfaction and BMI change in school-age children

Objective: Body image dissatisfaction (BID) in school-age children is positively associated with weight status in cross-sectional studies; however, it is uncertain whether BID is a risk factor for the development of adiposity over time. The aim of the present study was to examine the association of BID with changes in BMI in school-age children. Design: Longitudinal study. At recruitment, children were asked to indicate the silhouette that most closely represented their current and desired body shapes using child-adapted Stunkard scales. Baseline BID was calculated as the difference of current minus desired body image. Height and weight were measured at recruitment and then annually for a median of 2.5 years. Sex-specific BMI-for-age curves were estimated by levels of baseline BID, using mixed-effects models with restricted cubic splines. Setting: Public primary schools in Bogota, Colombia. Subjects: Six hundred and twenty-nine children aged 5-12 years. Results: In multivariable analyses, thin boys who desired to be thinner gained an estimated 5.8 kg/m(2) more BMI from age 6 to 14 years than boys without BID (P = 0.0004). Heavy boys who desired to be heavier or thinner gained significantly more BMI than boys without BID (P = 0.003 and P = 0.007, respectively). Thin girls who desired to be heavier or thinner gained significantly less BMI than girls without BID (P = 0.0008 and P = 0.05, respectively), whereas heavy girls who desired to be heavier gained an estimated 4.8 kg/m(2) less BMI than girls without BID (P = 0.0006). BID was not related to BMI change in normal-weight children. Conclusions: BID is associated with BMI trajectories of school-age children in a sex-and weight-specific manner.