Bariatric Surgery (Gastric Sleeve/Bypass)

Bariatric surgery is a group of laparoscopic gastrointestinal operations that produce sustained weight loss in patients with severe obesity, typically defined as a body mass index (BMI) of 40 or above, or 35 or above with significant obesity-related comorbidity such as type 2 diabetes, obstructive sleep apnoea or non-alcoholic steatohepatitis. The two most commonly performed procedures internationally are sleeve gastrectomy and Roux-en-Y gastric bypass, both of which restrict gastric volume and remodel gut hormone signalling. In a sleeve gastrectomy, approximately 80 percent of the stomach is removed using a stapling device, leaving a narrow tubular "sleeve" along the lesser curvature. In a Roux-en-Y gastric bypass, surgical staples create a small (15-30 mL) gastric pouch at the top of the stomach, which is then anastomosed directly to a limb of jejunum, bypassing the distal stomach and proximal small intestine. Both operations are usually performed laparoscopically and take one to three hours. Most patients lose 50-70 percent of excess body weight within the first 12-18 months, with significant improvement or remission of type 2 diabetes, hypertension and sleep apnoea. Lifelong dietary changes, vitamin and micronutrient supplementation, and follow-up are required because the operations alter absorption and gastric capacity permanently. Hospital stay is typically one to three days in NHS practice; international patients are generally advised to remain in-country for at least a week to allow staged dietary advancement and wound checks. Sources: NHS, NHS England, NICE guidance on obesity surgery.