The key procedural difference is that the Gastric Sleeve involves surgically removing approximately 80% of the stomach, leaving a narrow "sleeve." This works primarily by restricting food intake and reducing the hunger hormone (ghrelin). The Gastric Bypass is more complex; it creates a small stomach pouch and then reroutes (bypasses) a portion of the small intestine. This combines both restriction and malabsorption of calories/nutrients.
In terms of results, the Bypass typically leads to slightly greater and more durable weight loss in the long term (5+ years) and is highly effective for resolving type 2 diabetes. The Sleeve offers excellent weight loss but may have a slightly higher chance of weight regain. Both require a lifelong commitment to significant lifestyle changes, but the Bypass demands more diligence due to malabsorption. Patients must take life-long vitamin and mineral supplements (especially after Bypass), eat small, protein-first meals, and stay hydrated.
To find the right doctor, seek a bariatric surgeon who is a Fellow of the Royal College of Surgeons and works within a full multidisciplinary team (including dietitians and psychologists). Look for a surgeon certified by reputable bodies and choose a hospital designated as a Bariatric Surgery Centre of Excellence. The approximate private cost in the UK typically ranges from £9,000 to £15,000, with the bypass often at the higher end.
Post-surgery, you will follow a staged diet starting with liquids, then purées, soft foods, and finally solid foods over several weeks. Essential guidance includes chewing thoroughly, eating slowly, stopping at the first sign of fullness, avoiding drinking with meals, and committing to regular follow-up appointments for monitoring your health and nutritional status.