Higher BMI May Play Causal Role in Depression

November 20, 2018

The increased likelihood of depression in people with obesity stems from the psychological effect of being overweight and not only from associated illnesses such as diabetes, suggests a study published online in the International Journal of Epidemiology.

“Our research shows that being overweight doesn’t just increase the risks of chronic diseases such as cancer and cardiovascular disease,” said researcher Elina Hypponen, PhD, a professor at the University of South Australia in Adelaide. “It can also lead to depression.”

Researchers used genetic data from the UK Biobank for 48,000 people with depression and 290,000 control subjects.

The Intersection of Inflammation, Obesity, and Psychiatry

“We separated the psychological component of obesity from the impact of obesity-related health problems using genes associated with higher body mass index (BMI) but with lower risk of diseases like diabetes,” Dr. Hypponen explained. “These genes were just as strongly associated with depression as those genes associated with higher BMI and diabetes. This suggests that being overweight causes depression both with and without related health issues—particularly in women.” 

Meanwhile, men who had a very low BMI were more prone to depression than men who had a normal BMI and women with a low BMI.

Overall, the study concluded that higher BMI is likely to cause a higher risk of depression even in people who do not experience adverse metabolic consequences.

—Jolynn Tumolo


Tyrrell J, Mulugeta A, Wood AR, et al. Using genetics to understand the causal influence of higher BMI on depression. International Journal of Epidemiology. 2018 November 13;[Epub ahead of print].

‘Strongest evidence yet’ that being obese causes depression [press release]. Adelaide, Australia: University of South Australia; November 13, 2018.