To evaluate the causal effects of depression on obesity, longitudinal tests of the effect of depression on follow-up obesity status were meta-analyzed. Combining data from 16 studies the results confirmed that, after controlling for potential confounding variables, depressed compared to nondepressed people were at significantly higher risk for developing obesity. The risk among depressed people for later obesity was particularly high for adolescent females (odds ratio: 2.57, 95% CI: 2.27, 2.91). These findings highlight the importance of depression screening and treatment programs, especially among adolescents, to assist in the prevention of adult obesity.