It has been long known that the frequency of overweight and obese people is higher among depressed and bipolar patients than in the general population. The marked alteration of body weight (and appetite) is one of the most frequent of the 9 symptoms of major depressive episode, and these symptoms occur during recurrent episodes of depression with a remarkably high consequence. According to studies with representative adult population samples, in case of obesity (BMI over 30) unipolar or bipolar depression is significantly more frequently (20-45%) observable. Since in case of depressed patients appetite and body weight reduction is observable during the acute phase, the more frequent obesity in case of depressed patients is related (primarily) not only to depressive episodes, but rather to lifestyle factors, to diabetes mellitus also more frequently occurring in depressed patients, to comorbid bulimia, and probably to genetic-biological factors (as well as to pharmacotherapy in case of medicated patients). At the same time, according to certain studies, circadian symptoms of depression give rise to such metabolic processes in the body which eventually lead to obesity and insulin resistance. According to studies in unipolar and bipolar patients, 57-68% of patients is overweight or obese, and the rate of metabolic syndrome was found to be between 25-49% in bipolar patients. The rate of metabolic syndrome is further increased by pharmacotherapy. Low total and HDL cholesterol level increases the risk for depression and suicide and recent studies suggest that omega-3-fatty acids possess antidepressive efficacy. Certain lifestyle factors relevant to healthy metabolism (calorie reduction in food intake, regular exercise) may be protective factors related to depression as well. The depression- and possibly suicide-provoking effect of sibutramine and rimonabant used in the pharmacotherapy of obesity is one of the greatest recent challenges for professionals and patients alike.