Hypovitaminosis D is highly prevalent in the general population, particularly in obese individuals. Besides being associated with obesity, vitamin D deficiency seems to be involved in the pathogenesis of insulin resistance and low-grade chronic inflammation. In addition, it has been reported that individuals with low vitamin D levels are at increased risk for cardiovascular diseases. A healthy diet and weight loss are cornerstones in the prevention of cardiovascular diseases. Vitamin D supplementation could increase the beneficial effects of these lifestyle interventions. The purpose of this study is to assess whether vitamin D supplementation in conjunction with a hypocaloric diet improves the cardiometabolic profile of overweight/obese subjects to a greater extent than diet alone.