Although the available evidence suggests a greater weight loss with surgical treatments than with non-surgical, no conclusive data has been found as regards comorbidities and long-term life quality. It must be taken into account that most studies were performed to subjects with a BMI of 35-40 who could not lose weight with conventional medical treatments. Of all the surgical techniques, the most accepted and well-known is the gastric bypass. The different laparoscopic techniques have proved to be relatively safe, with a shorter hospital stay and lower rates of readmission and complications. However, their long term efficacy is still unknown. It is a very complex treatment which implies a mayor surgical procedure, and which affects the patient physically, psychologically and socially. For these reasons the surgical treatments for obesity are not always covered by health organizations. The coverage is restricted to special patients who comply with strict criteria: - BMI over 40 for more than 5 years, or BMI over 35 with other important comorbidities. - At least one year of documented attempts to decrease weight including diet, physical exercise and drug treatment. - Psychological assessment of the patient s state to undergo such a treatment. - Over 18 years of age.