How much weight do patients lose following bariatric surgery?
Success following bariatric surgery is determined by both weight loss and improvement in obesity-related comorbidities. Most surgical studies report outcomes as percentage of excess weight lost (EWL) and consider loss of at least 50% of excess weight as a minimum criterion for success. The lap band typically produces 40% to 60% EWL gradually over 2 to 3 years but has up to a 50% failure and explant rate at 10 years. The gastric bypass typically produces 60% to 80% EWL rapidly over 2 years with fairly low rates of weight regain (approximately 10%–15%) and an estimated 10% overall failure rate. The biliopancreatic diversion is the most effective weight loss procedure and results in loss of 80% of excess weight maintained over the long term. Its popularity is limited by a small percentage of patients who have excessive weight loss or severe vitamin, mineral, and protein deficiencies. The sleeve gastrectomy has shown effective and durable weight loss, with up to 80% of patients achieving 60% EWL at 5 years. Long-term data are still lacking, but the overall failure rate is estimated at 20%.