Obesity Leads to Depression via Social and Metabolic Factors
New research provides further evidence that a high body mass index (BMI) leads to depressed mood and poor well-being via social and physical factors.

Higher adiposity is an established risk factor for psychiatric diseases including depression and anxiety. The associations between adiposity and depression may be explained by the metabolic consequences and/or by the psychosocial impact of higher adiposity.

Researchers performed one- and two- sample Mendelian Randomisation(MR) in up to 145?668 European participants from the UK Biobank to test for a causal effect of higher adiposity on ten well-validated mental health and wellbeing outcomes derived using the Mental Health Questionnaire (MHQ). We used three sets of adiposity genetic instruments: a) a set of 72 BMI genetic variants, b) a set of 36 favourable adiposity variants and c) a set of 38 unfavourable adiposity variants.

They additionally tested causal relationships (1) in men and women separately, (2) in a subset of individuals not taking antidepressants and (3) in non-linear MR models. Two-sample MR provided evidence that a genetically determined one standard deviation (1-SD) higher BMI (4.6?kg/m2) was associated with higher odds of current depression and lower wellbeing. Findings were similar when using the metabolically favourable and unfavourable adiposity variants, with higher adiposity associated with higher odds of depression and lower wellbeing scores.

This study provides further evidence that higher BMI causes higher odds of depression and lowers wellbeing. Using genetics to separate out metabolic and psychosocial effects, our study suggests that in the absence of adverse metabolic effects higher adiposity remains causal to depression and lowers wellbeing.

Source: https://academic.oup.com/hmg/advance-article/doi/10.1093/hmg/ddab204/6322471