The prevalences of several risk factors and diseases are dramatically increased in obesity. In contrast, considerable inconsistencies have been reported for the relationship of obesity to the incidence of cardiovascular disease and total mortality. Suggested reasons for these inconsistencies have been confounders and surrogate risk factors, but the single most important cause is that far-reaching conclusions have been drawn from small short-term studies. Several large studies have recently proven that the incidence of cardiovascular disease is increased in obesity. Correct classification of obesity and its subgroups is also of great importance. Visceral obesity constitutes one subgroup at high risk. It seems possible to link diabetes, hypertriglyceridemia, reduced fibrinolysis, and hypertension to elevated portal free fatty acid concentrations because of an increased visceral adipose tissue depot. The quantitation of visceral adipose tissue has been improved by techniques based on computed tomography (CT) and by CT-calibrated anthropometric methods. Results from controlled intervention studies of obesity are entirely lacking but one such study has been started.