"Both depression and obesity are widely spread problems with major public health implications," the authors write as background information in the article. "Because of the high prevalence of both depression and obesity, and the fact that they both carry an increased risk for cardiovascular disease, a potential association between depression and obesity has been presumed and repeatedly been examined." Understanding the relationship between the two conditions over time could help improve prevention and intervention strategies.

Evidence of a biological link between overweight, obesity and depression remains uncertain and complex, but several theories have been proposed, the authors note. Obesity may be considered an inflammatory state, and inflammation is associated with the risk of depression. Because thinness is considered a beauty ideal in both the United States and Europe, being overweight or obese may contribute to body dissatisfaction and low self-esteem that places individuals at risk for depression. Conversely, depression may increase weight over time through interference with the endocrine system or the adverse effects of antidepressant medication.