In this paper, we focus on the causes and consequences of adolescent obesity from an economic perspective. The paper examines the determinants of obesity and its role in influencing early school leaving amongst adolescents in the province of Salerno in Southern Italy. A simple human capital investment model is employed and this provides a framework within which to analyse the interrelated 'decisions' regarding schooling and overeating, taking into account the importance of time preference and the differential effects of adolescent obesity for males and females. We find that: a) there is a strong and robust positive effect of obesity on early school leaving; b) there are significant gender differences in the nature of this relationship; and, c) although not statistically significant, there is support for the idea that contextual factors – such as the type of school attended - are important in determining the effects of obesity on early school leaving. These findings have important policy implications. In particular, evidence on the positive causal link running from obesity to early school leaving suggests: i) that action aimed at reducing obesity – such as the encouragement of sporting activity - may also have beneficial effects in terms of reducing early school leaving rates; ii) the introduction of financial incentives to encourage educational participation; and, iii) the significant differences identified between young men and young women suggest the adoption of some gender- specific policy measures.