Interestingly, prior studies have postulated that the association between depression and being overweight/obese is bidirectional.6,27 One explanation for this finding is based on the inflammatory theory of depression in which proinflammatory cytokines, such as IL-6 and tumor necrosis factor α, have been reportedly observed in patients with depression, and concurrently, inflammation is correlated with metabolic abnormalities (e.g., leptin).28,29. This evidence concerns the gene LEP and major depressive disorder.