Overweight and obese people can be at increased risk of depression, even in the absence of other health problems, warning new research.
The research, published in the International Journal of Epidemiology, showed that the psychological effect of overweight causes depression, rather than associated illnesses such as diabetes.
"Our research shows that overweight does not increase the risks of chronic diseases such as cancer and cardiovascular disease, it can also lead to depression," said co-author, Elina Hypponen, Professor of Studies at the University of South Australia.
For the study, researchers looked at UK Biobank data from more than 48,000 people with low depression, compared to a management group of over 290,000 people born between 1938 and 1971, which provided medical and genetic information.
Hospital data and self-reporting were used to determine depression.
The team used a genetic research approach to investigate the causal connection between the two conditions.
They separate the psychological element of obesity from the effect of obesity-related health problems, using genes that are associated with higher BMI but lower risk of diseases such as diabetes.
"These genes were equally strong in relation to depression with those genes that are associated with higher BMI and diabetes, which suggests that overweight causes depression with and without related health problems – especially in women, "says Hypponen.
"Our sound genetic analysis brings to the conclusion that the psychological effect of obesity is likely to cause depression. This is important to help target efforts to reduce depression depression, which is made She's harder for people to adopt healthy lifestyle habits, "said Jess Tyrrell of the University from the Exeter Medical School in Britain.