It might sound obvious, but scientists say obesity and depression go hand in hand among teenage girls. Either condition worsens the risk for the other in adolescent girls, a new study from Rutgers University suggests.

Though past study has long supported a strong association between the two conditions within this population, scientists may now say the two increase risk for each other — a correlation not found among boys and young men, according to study leader Naomi Marmorstein. Adolescent girls who were diagnosed with either condition were highly likely to develop the other by the time they reached adulthood.

The association held for girls and women ages 14 to 24. "When an adolescent girl receives treatment for depression, the clinician might consider incorporating something relating to healthy eating and activity," she said. "Exercise can assist in the treatment of depression to begin with, so it seems like a good reason to combine prevention efforts for both depression and obesity."

Marmorstein and her colleagues say clinicians should target prevention efforts for both conditions among girls in childhood and adolescence, encouraging girls to participate in sports and to get other forms of exercise.

In the study, the researchers recorded the heights and weights of 1,500 participants from the state of Minnesota, including boys and girls ages 11, 14, and 24, as well as young men and women ages 20 and 24. The participants were screened for major depression through personal interviews, and then followed as they aged. The researchers checked back with them at intervals, looking for signs of depression and weight gain by age 14 and then at 20 and then 24.

"Adolescence is a key developmental period for both obesity and depression, so we thought it significant to look at the onset of these disorders at an early age,” Marmorstein said. "When a person is young, she is still developing eating and activity patterns, as well as coping mechanisms. So if she experiences a depressive episode at age 14, she may be more at risk for having an onset of unhealthy patterns that persist."

Although why the two conditions are related was not the study’s focus, Marmorstein and her colleagues say they believe that adolescent girls starting to establish romantic relationships may be self-conscious with regard to body image.

Source: Marmorstein, N.R., Lacono, W.G., Legrand, L. Obesity and depression in adolescence and beyond: reciprocal risks. International Journal of Obesity. 2014.