In the study, published in the January/February issue of General Hospital Psychiatry, researchers interviewed 4,641 female health-plan enrollees, ages 40 to 65, by phone. The women responded to items on height, weight, exercise levels, dietary habits and body image. They also completed the Patient Health Questionnaire, a measure of depression symptoms.

Women with clinical depression were more than twice as likely to be obese, defined as having a body-mass index (BMI) of 30 or more; likewise, obese women were more than twice as likely to be depressed.

—"Obesity, Depression Often Coexist In Middle-Aged Women," Science News

Results of the research showed, that people, having adiposity, suffered from anxious and emotional disorders, including depression, 25% more often. At the same time, fatty people abused alcohol and drugs 25% less frequently, than their slenderer brothers.

Now scientists are still not ready to answer a question, whether depresion is a reason or result of adiposity, as both variants are quite possible. It’s known, that depressed people experience fall of physical activity. Moreover, medicines, used for its treatment, can cause weight gain. On the other hand, fatty people become butts more often, what surely affects their mood.
Both depression and adiposity are widespread. About one third of adult Americans suffers from adiposity, and depression is detected in 10% of population (about 21 millions of people).

—"Overweight people suffer from depression more often," Woman’s Passions: Women’s Lifestyle Magazine