The aim of this study is find out how CBT-based weight loss program affects on eating behavior, weight loss, mood symptoms and risk for coronary heart diseases and type 2 diabetes and applicability of the program to obesity treatment among patients with comorbid depression. Our hypothesis is that the CBT-based intervention improves long-term weight management results and supports positively the change in eating behavior and the risk for CHD on type 2 DM. The study is randomized controlled one-year intervention study with 1 year follow-up. Study subjects are adult obese (BMI\>35) subjects with comorbid depression. Number of randomized study subjects will be 80, 40 in intervention group, 40 in control group. Intervention group will proceed through a 52-week CBT-based weight loss group intervention. The aim of the intervention is to modify eating behavior and lifestyle factors affecting weight and weight maintenance. There will be 22 group counselling of 90 minutes divided in five modules and also three individual person-centered counselling visit, during which participants had an opportunity to discuss their personal concerns about diet and weight loss plan. Control group will receive the usual care of obesity in Kuopio University hospital. (4-8 individual 45-minute visit conducted by dieticians) Study visits are at baseline and one and 2 years after baseline. For example eating behavior, health behavior, motivation and depression are studied with questionnaires. Weight, waist circumference, height and blood pressure are measured. Laboratory tests (lipid, glucose etc) are taken.