Body mass index and suicidal behaviors: A critical review of epidemiological evidence

Abstract Introduction Obesity has been associated with an elevated risk of depression and other mental health symptoms. An increasing number of robust prospective studies, however, counter-intuitively and consistently suggested that body mass index (BMI) was inversely associated with the risk of completed suicide in a dose-response fashion. The current contribution appraised the epidemiological evidence and examined the nature of the purported relationship. Method We conducted a systematic review of English publications of original studies using the terms “obesity”, “overweight”, “body mass index”, “BMI”, “attempted suicide”, “completed suicide”, “suicide ideation”, “suicidal behaviors” and “suicide”. Data were extracted primarily through MEDLINE and PUBMED databases. Results Almost all cohort studies reported an inverse relationship between BMI and the risk of completed suicide irrespective of region of origin and the gender of study participants. Overall, among men, a high BMI was associated with a low risk of attempted or completed suicide. There was a paradox among women, namely, a high BMI was associated with an elevated risk of attempted suicide but a low risk of completed suicide. Limitations As a narrative review, the current report was interpretive and qualitative in nature. Conclusion Consideration of observational data, methodological issues stemmed from the rarity of deaths by suicide, homogeneity of study populations, heterogeneity of suicide methods, and the corresponding neurobiological changes made interpretation difficult. Intercultural cohort observations across countries may help to weigh the contributions from biological and socio-cultural factors. The purported association not only represents a scientific challenge, it's also an opportunity potentially leading to important insights into prevention of suicide death.