From literature, the mean excess body weight loss is 77.65% with standard deviation of 21% for Duodenal Switch bariatric surgery. If there is in truth no difference between the Duodenal Switch and SADI for excess body weight loss, then 140 patients (70 per group) are required to have 80% power for the lower limit of a one-sided 97.5% confidence interval (or equivalently a 95% two-sided confidence interval) will be above the non-inferiority limit of -10%.