The widely propagated morbidity and mortality risks of obesity appear somewhat exaggerated, except for morbid obesity (BMI > 40 kg/m2) and for high risk obese subgroups concerning diabetes mellitus, hypertension, metabolic syndrome and obstructive sleep apnea syndrome. Non-medical reasons represent a major component of the social pressure that is presently experienced by obese persons in our society. Weight reduction represents the primary therapeutic approach in overweight patients with type 2 diabetes, hypertension, metabolic syndrome and obstructive sleep apnea, and it may be recommended in high-risk individuals for primary prevention of these diseases. Massive obesity is associated with excess mortality, especially in younger, physically inactive men with upper-body-segment obesity. It is widely assumed that weight reduction will lead to a reduction of excess mortality in these individuals; so far, however, there is no proof for this assumption. Non-medicamentous conservative therapeutic approaches to weight reduction have the advantage of safety, even though their long-term efficacy is generally disappointing. There are no randomized, controlled trials to prove a reduction of morbidity or mortality risks and of therapeutic safety for pharmacological, invasive or surgical methods to treat obesity.