Ongoing research shows there may be a biological link between depression and gaining weight.

While researchers still don’t understand fully the complex and tangled relationship between depression and weight gain, they do know “there are specific biological causes that link the weight gain with depression itself,” says Dr. Richard Shelton, vice chair for research at the University of Alabama at Birmingham’s School of Medicine’s Department of Psychiatry and Behavioral Neurobiology and a member of the UAB Nutrition Obesity Research Center. “It’s a reciprocal relationship.”

In other words, the relationship between depression and obesity is interconnected. According to JAMA Psychiatry, a person who is depressed has an increased risk of becoming obese and a person who is obese has an increased risk of becoming depressed.

There are a lot of behavioral reasons why depression could contribute to weight gain — a person who is depressed might not feel motivated to exercise or might seek comfort in foods that are high in fat and sugar. They may take antidepressant medication, which according to research published in JAMA Psychiatry show can cause modest weight gain.

Likewise, social factors and physical problems associated with obesity – such as poor self-esteem, weight-related health problems, or trouble getting out to socialize – can negatively impact a person’s emotional state.

But Dr. Shelton says the connection between obesity and depression appears to be biological, not behavioral. Researchers are still trying to understand exactly which biological mechanisms are to blame. Some people with depression have elevated levels of cortisol, a hormone associated with stress, which may help explain the weight gain, Dr. Shelton says. Or, he says, it could be that the sympathetic nervous system, which is more active in people with depression and which helps regulate metabolism, is to blame.

While more research is needed to understand the role biological mechanisms play, Dr. Shelton says people suffering from depression can take steps to prevent weight gain. He recommends:

• Focus on diet. “If people are really intent on controlling this process they need to focus on their diet,” he says. He recommends avoiding processed foods and eating a whole food diet like the Mediterranean diet, which offers a wide variety of health benefits.
• Exercise. Exercise not only burns calories, it helps people manage their symptoms of depression by releasing “feel good” brain chemicals called endorphins and by providing distraction.
• Talk to your health care provider about adding cognitive behavioral therapy to your treatment plan.

While weight management is important to overall health, Dr. Shelton cautions that individuals who have been prescribed antidepressants should continue to take their medication as directed.

“A lot of the weight gain attributed to medication in the past is likely attributable to biological activity,” he says. Although they might notice an extra pound or two, chances are “it is not an enormous amount so always treat the depression to full remission.”