‘Strongest evidence yet’ that being obese causes depression

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New research has found the strongest evidence yet that obesity causes depression, even in the absence of other health problems.

The research by UniSA and the University of Exeter in the UK, shows that the psychological impact of being overweight causes depression, rather than associated illnesses such as diabetes.

Researchers looked at UK Biobank data from more than 48,000 people with depression, comparing them with a control group of more than 290,000 people born between 1938 and 1971, who provided medical and genetic information.

Hospital data and self-reporting were used to determine whether people had depression.

Director of the Australian Centre for Precision Health, UniSA Professor Elina Hypponen, who co-led the study, says the team took a genomic approach to their research.

“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,” Prof Hypponen says.

“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.”

At the other end of the BMI spectrum, very thin men are more prone to depression than either men of normal weight or very thin women.

“The current global obesity epidemic is very concerning,” Prof Hypponen says. “Alongside depression, the two are estimated to cost the global community trillions of dollars each year.

“Our research shows that being overweight doesn’t just increase the risks of chronic diseases such as cancer and cardiovascular disease; it can also lead to depression,” Prof Hypponen says.

The research is published in the International Journal of Epidemiology.

*Obese individuals are classified as people with a body mass index (BMI) greater than 30 kg/m².

To work out your BMI:

  • divide your weight in kilograms (kg) by your height in metres (m)

  • then divide the answer by your height again to get your BMI.

You can also use a BMI healthy weight calculator.

content provided by NHS Choices