Overweight can lead to depression, the researchers said.
Previous studies have shown that obese people are more likely to suffer from depression, but it is unclear whether depression causes weight changes or vice versa.
Experts say that in the largest studies of this kind, genetic variation associated with a high body mass index (BMI) can cause depression and has a stronger impact on men than women. Also, research suggests that it can affect factors such as body image.
"People overweight in the population are depressed and may not be at least partially. [a] Causal influence of BMI [on] Depression, "said Professor Tim Frayling, co-author of the study at Exeter Medical School.
According to a study in the International Journal of Epidemiology, researchers in the UK and Australia are studying how they used data from the UK Biobank. The research focuses on 500,000 participants aged between 37 and 73 who were recruited in 2006-10.
The researchers observed 73 genetic mutations associated with high BMI, leading to a higher risk of diseases such as diabetes and heart disease. They also saw 14 genetic variants linked to a high percentage of body fat, but at a lower risk of such health problems.
The team investigated responses to the questionnaires, including participants' hospital data and the GP or psychiatric self-report of anxiety or depression. The researchers identified about 49,000 participants who were convinced of depression.
Overall, people with high BMI are more likely to have depression.
The researchers found that breast cancer was associated with depression as genetically increased BMI. Depression is more pronounced in women than in men. The results were retained even if additional tests were performed, such as repeated analyzes of data from a large international project called the Psychiatric Genomics Consortium, except for those with a family history of depression.
Focusing on 73 genetic variants and taking age and gender into account, the odds of developing depression increased by 18% overall and by 23% for women with a 4.7-point increase in BMI.
When teams collected data from multiple sources, they found that 14 genetic variants that increase body fat, but metabolism is not associated with bad health, are more likely to have depression.
"This suggests that psychological components are as powerful as any physiological component. [the latter] "Frayling suggested that a poor body image could be a mechanism in the play.
There are some limitations to this study. Mainly European ancestors looked at individuals who were white and included some self-reported data.
Although this study does not show that weight gain increases the risk of depression for other reasons, Frayling said it is possible. "that is [one] We speculated that a greater impact on BMI would have a greater impact on depression.
Naveed Sattar, a professor at the University of Glasgow, welcomed the study. "This study is probably the most powerful study that shows that weight can contribute to depression," he said. "Of course, many other factors can cause depression, but weight loss can help improve mental health, but in general it can reduce the risk of depression by keeping it sparse."