This review, updated in 2014, assesses the effects of bariatric (weight loss) surgery for overweight and obese adults, including its impact on comorbidities. The review includes 22 randomized controlled trials with 1798 participants, comparing surgical interventions with non-surgical management or with each other. The studies followed participants for up to 10 years, with most lasting 12 to 36 months. The overall quality of evidence was moderate. Key findings include: - Surgery generally led to greater weight loss and BMI reductions compared to non-surgical interventions. - Laparoscopic Roux-en-Y gastric bypass (LRYGB) achieved significantly greater weight loss and BMI reductions up to five years post-surgery compared to laparoscopic adjustable gastric banding (LAGB). - Biliopancreatic diversion with duodenal switch (BDDS) resulted in greater weight loss than RYGB in morbidly obese patients. - Gastric bypass and sleeve gastrectomy (SG) had similar outcomes in terms of weight loss, but SG had better outcomes in terms of comorbidities and complications. - Isolated sleeve gastrectomy (ISG) led to better weight-loss outcomes than LAGB after three years. - Laparoscopic gastric imbrication and SG had similar outcomes in one trial. The review highlights that while surgery generally improves weight-related outcomes and comorbidities, the long-term effects of surgery remain unclear due to the limited duration of most studies. Adverse event rates and reoperation rates were often poorly reported. The review also notes that the use of bariatric surgery to treat comorbidities in overweight individuals is less well-evaluated.This review, updated in 2014, assesses the effects of bariatric (weight loss) surgery for overweight and obese adults, including its impact on comorbidities. The review includes 22 randomized controlled trials with 1798 participants, comparing surgical interventions with non-surgical management or with each other. The studies followed participants for up to 10 years, with most lasting 12 to 36 months. The overall quality of evidence was moderate. Key findings include: - Surgery generally led to greater weight loss and BMI reductions compared to non-surgical interventions. - Laparoscopic Roux-en-Y gastric bypass (LRYGB) achieved significantly greater weight loss and BMI reductions up to five years post-surgery compared to laparoscopic adjustable gastric banding (LAGB). - Biliopancreatic diversion with duodenal switch (BDDS) resulted in greater weight loss than RYGB in morbidly obese patients. - Gastric bypass and sleeve gastrectomy (SG) had similar outcomes in terms of weight loss, but SG had better outcomes in terms of comorbidities and complications. - Isolated sleeve gastrectomy (ISG) led to better weight-loss outcomes than LAGB after three years. - Laparoscopic gastric imbrication and SG had similar outcomes in one trial. The review highlights that while surgery generally improves weight-related outcomes and comorbidities, the long-term effects of surgery remain unclear due to the limited duration of most studies. Adverse event rates and reoperation rates were often poorly reported. The review also notes that the use of bariatric surgery to treat comorbidities in overweight individuals is less well-evaluated.