Obesity, defined as a body mass index of 30 kg/m2, or more is considered to be the decisive factor for the development of the metabolic syndrome and numerous other diseases prevalent in affluent societies. The high level of comorbidity and the shortening of life expectation underscore the need for an evidence-based, risk-stratified treatment strategy. Major elements of the latter are a hypocaloric diet that is also satiating, an increase in physical activity, specific behavioral changes and, where indicated, weight-reducing medication. For the treatment of extreme obesity, such surgical procedures as gastric banding or a gastric bypass are also available.