Roux-en-Y gastric bypass

The oldest and most extensively studied bariatric operation, particularly effective when severe obesity is combined with type 2 diabetes or severe reflux.

Typically considered for patients with a BMI of 40 or above, or 35 or above with significant obesity-related comorbidities (type 2 diabetes, sleep apnoea, severe reflux, hypertension, non-alcoholic fatty liver disease).

Particularly well suited to patients whose primary goal is metabolic (diabetes control) or whose reflux is severe.

Laparoscopically, through five small keyhole incisions. A small pouch (about the size of a hen’s egg, roughly 30 mL) is created from the upper stomach and separated from the rest.

A segment of small intestine (the “Roux limb”) is brought up and joined to this pouch. A second connection restores normal digestion downstream.

The bypass both restricts intake and alters gut hormones that signal hunger and satiety.

Most patients lose 60–80% of their excess body weight over 12–18 months. Type 2 diabetes goes into remission or improves substantially in the majority of patients (often within weeks, before major weight loss has occurred). Sleep apnoea, hypertension, high cholesterol and fatty liver also commonly improve.

2–3 day hospital stay. A staged diet over the first month: clear liquids for the first few days, full liquids for 1–2 weeks, puréed foods for weeks 2–4, then soft and finally regular foods, always in small, protein-first portions.

Lifelong daily vitamins (multivitamin, calcium + vitamin D, iron, vitamin B12) and twice-yearly follow-up for the first two years, then annually. Some patients experience “dumping syndrome” (flushing, nausea, lightheadedness after very sugary or fatty meals) which usually improves with dietary adjustment.

A more complex operation than sleeve gastrectomy. Reversible in principle, but rarely reversed. Not recommended for patients with certain chronic nutritional deficiencies or specific intestinal diseases; these are reviewed in consultation.