Overweight and obese people may have a risk of depression, even if there are no other health problems, warning new research.
The study, published in the International Journal of Epidemiology, showed that the psychological effect of overweight causes depression and related illnesses such as diabetes.
"Our research shows that overweight does not only increase the risks of chronic diseases such as cancer and cardiovascular disease but may also lead to depression," says Professor Elina Hypponen, University of South Australia.
In the study, researchers surveyed more than 48,000 human antidepressants UK Biobank data by comparing over 290,000 people born between 1938 and 1971 who provided medical and genetic information.
Hospital information and self-reporting were used to determine whether people had depression.
The team used a genetic research method to find out the causal link between these causes.
They differed the psychological proportion of obesity from the effects of obesity due to obesity using genes associated with higher BMI, but smaller diseases such as diabetes.
"These genes were as well related to depression as those associated with higher BMI and diabetes, suggesting that overweight causes depression both and with no associated health problems – especially in women," Hypponen said.
"Strong genetic analysis concludes that the psychological effects of obesity are causing depression, which is important to helping efforts to reduce depression, which makes people much more difficult to adopt healthy lifestyles," said Jess Tyrrell at Exeter Medical School in Britain.