Separating Boys and Girls and Increasing Weight? Assessing Impacts of Single-Sex Schools through Random Assignment in Seoul

Jaesung Choi, Sungkyunkwan University
Hyunjoon Park, University of Pennsylvania

A growing body of research reports associations of school contexts, in which adolescents interact with their peers and react to adolescent culture, with adolescents’ weight and weight-related behaviors. One interesting, but under-researched, dimension of school context that potentially matters for adolescents’ weight is the gender composition. If boys and girls are separated into single-sex schools, they might become less concerned about physical appearance, which results in increased weight. Utilizing a unique setting in Seoul, Korea where students are randomly assigned into single-sex and coeducational schools within school districts, we estimate causal effects of single-sex schools on weight and weight-related behaviors. Our results show that students attending single-sex schools are more likely to be overweight, and the effects are more prominent among girls. We also find that girls in single-sex schools are less likely to engage in weight control behaviors.