Risk-Benefit Analysis of Bariatric Surgery Discussions around a risk-benefit analysis of bariatric surgery focus particularly on the mortality risk, the impact of obesity-associated comorbidity and the associated health expenditure. The literature indicates that the adjusted risk of premature death in nonoperatively treated morbid obesity with a BMI > 35 kg/m(2) (or 40 kg/m(2)) is 29-40%. In contrast, 30-day lethality in bariatric surgery has fallen markedly in recent years and currently lies between 0.3 and 2%. Obesity-associated morbidity is markedly improved through surgery in line with the indications. It has been possible to demonstrate in this connection that the rate of cure or improvement for type II diabetics is between 38 and 100%, that for hypercholesterolemia between 30 and 94%, and that for hypertonic heart disease between 31 and 87%. Coexistent sleep apnea is cured in 71-100% of cases, and depressive illnesses are alleviated in approximately half the patients. Health expenditure falls in the postoperative follow-up through the optimization of obesity-associated comorbidity. It may therefore be assumed that, after modern bariatric surgery, the costs of the operation will be amortized in approximately 2-4 years. After this, annual health expenditure for nonoperatively treated patients rises by the factor 3-5. Taking these three aspects into account, there seem to be no conservative alternatives to indication-appropriate bariatric surgery.