LAUSR

Background The association between body size, weight change and depression has not been systematically summarised, especially for individuals who are underweight. Aims To conduct a systematic review and a meta-analysis to examine the association between indices of body size, weight change and depression. Method A total of 183 studies were selected. Fully adjusted hazard ratios (HRs) or odds ratios (ORs) were extracted. A total of 76 studies contributed to data synthesis with a random-effect model, and subgroup analyses were conducted to evaluate the effect of potential moderators. Results In cohort studies, underweight at baseline increased the risk of subsequent depression (OR = 1.16, 95% CI 1.08–1.24). Overweight (BMI 25–29.9 kg/m2) showed no statistically significant relationship with depression overall; however, the subgroup analyses found different results according to gender (men: OR = 0.84, 95% CI 0.72–0.97, women: OR = 1.16, 95% CI 1.07–1.25). In cross-sectional designs, obesity with BMI >40kg/m2 showed a greater pooled odds ratio than obesity with BMI >30kg/m2. Conclusions Both underweight and obesity increase the risk of depression. The association between overweight and depression differs by gender.