 All patients will be subjected to a treatment regimen aimed at achieving optimal glycemic, lipid, BP and body weight targets, as established by current guidelines and including glucose-, lipid- and BP-lowering agents as needed. For ethical reasons, drugs will be also adjusted throughout the study to attain target levels and to account for reduced needs. Since all patients are overweight or obese, caloric intake 55 complex carbohydrates, 30 fat, and 15 protein will be reduced to obtain a negative balance of 500 kcalday. Requirements will be calculated by adding the estimated energy expenditure from PA to basal metabolism. Adherence to diet will be verified by the use of food diaries and dietary prescriptions will be adjusted at each intermediate visit. Patients with vitamin D levels ranging from 10 to 20 ngdl will be treated with cholecalciferol 25.000 IU every 2 weeks for 2 months, then with cholecalciferol 25.000 IU every months, whereas those with vitamin D levels ranging from 20 to 30 ngdl will be given cholecalciferol 25.000 IU every month. At 6 months participants, will be re-evaluated and treatment will be discontinued in case of vitamin D values 30 ngdl or continued for additional 6 months at the doses indicated above, and so on until the end of the study. 