Influence of within-class age differences on adolescents’ eating behaviors

This study examines within-class age differences as a novel determinant of adolescents’ dietary behaviors, isolating it from confounders such as absolute age, season of birth, and country-specific school entry rules. Using a multi-country dataset of over 600,000 European students, we find that younger students within a class exhibit poorer dietary habits. Since confounders are controlled for, these effects are likely driven by peer influence. The findings are robust across various model specifications, with minimal variation across gender, socio-economic status, and family composition, highlighting the broad relevance of relative age effects on adolescent diet.