People who are depressed are more likely to become obese, and obese people are more likely to become depressed.

Reporting in the Archives of General Psychiatry, the studies authors conducted an analysis of 15 previously published studies involving more than 55,000 people. They found a two-way relationship between obesity and depression, saying, “Obese persons had a 55 percent increased risk of developing depression over time, whereas depressed persons had a 58 percent increased risk of becoming obese.”

The reason for the links isn’t clear, though the authors say that there are likely to be a number of reasons, ranging form unrealistic ideals of beauty and thinness to a change in metabolism in people who are depressed. Side effects from antidepressant medication could also lead to obesity and inflammation caused by obesity could lead to depression.

“Because weight gain appears to be a late consequence of depression, care providers should be aware that within depressive patients weight should be monitored. In overweight or obese patients, mood should be monitored. This awareness could lead to prevention, early detection and co-treatment for the ones at risk, which could ultimately reduce the burden of both conditions,” they conclude.