Body mass index and risk of suicide among one million US adults

Background: Body mass index (BMI) has been linked with both increased and decreased risk of suicide attempts and deaths. Methods: In a prospective cohort study of 1.1 million adults, participants reported their anthropometric and other characteristics in 1982. Participants were followed for cause-specific mortality through 2004. Results: A total of 2231 participants died of suicide during 21.6 million person-years of follow-up. Compared with a BMI of 18.5-22.9 kg/m, adjusted hazard ratios for completed suicide were 0.99 (95% confidence interval = 0.72-1.37), 0.78 (0.69-0.88), 0.73 (0.65-0.82), 0.72 (0.62-0.83), 0.77 (0.65-0.92), and 0.55 (0.36-0.83) for BMI values <18.5, 23.0-24.9, 25.0-27.4, 27.5-29.9, 30.0-34.9, and ≥35.0 kg/m, respectively. The relationship was consistent among men and women and across geographic regions, but was limited to married individuals (test for interaction, P = 0.009). Conclusions: The risk of death from suicide is inversely related to BMI in middle-aged and older adults.