Morbid obesity has a major impact on both the duration and quality of life. It can be accompanied by vascular, respiratory, joint and metabolic complications (such as type 2 diabetes) which can shorten life expectancy, and some cancers are also more frequent in obese individuals. Recent demographic data show an increase in the prevalence of obesity in France, as in most western countries, particularly in young subjects. Morbid obesity (BMI > 40 kg/m2) now affects more than 1.1% of the population. Medical and dietary management has shown only modest and transient efficacy, and surgical procedures have thus been developed, notably using the laparoscopic approach. Four procedures are generally used: two are restrictive (gastric banding, LAGB; and sleeve gastrectomy, SG), one is mixed (gastric bypass, GBP) and one is malabsorptive (biliopancreatic diversion, BPD). Unfortunately, the more effective the procedure, the higher the risk. With LAGB, SG, GBP and BPD, excess weight loss at two years is respectively 49%, 56%, 63.3% and 73.3%, and the mortality rates are 0.1%, 0.15%, 0.5% and 0.8%. Bariatric surgery appears to reduce overall mortality by 40% at ten years (56% for myocardial infarction, 92% for diabetes, and 60% for cancer). It has recently emerged that bariatric surgery can also improve metabolic diseases like type 2 diabetes, independently of excess weight loss. Bariatric surgery is cost-effective after 3.5 years. This may not be the ideal treatment for obesity, but it is likely to remain the most effective treatment for another 10 to 20 years. Cooperation between physicians and surgeons, based on official guidelines like those published by the French authorities, should allow more morbidly obese patients to benefit from the excellent results of this surgery, which improves both quality and duration of life and lessens the economic and social costs of obesity.