Gastric Bypass

Your surgeon staples off a small pouch at the top of the stomach, about the size of an egg, and joins the small bowel directly to it. A second join further down brings back the digestive juices from the bypassed stomach and the first stretch of bowel.

Two mechanisms work together. The pouch holds very little, so meals are small; and food skips part of the bowel, so fewer calories are absorbed and the gut hormones that control appetite and blood sugar change substantially. That hormonal shift is why blood sugar often improves within days, before much weight has been lost.

The bypassed stomach stays in the body and is not removed. Because food no longer passes through the part of the bowel where iron, calcium and vitamin B12 are best absorbed, supplements and blood tests are lifelong and not optional.

You will have been through assessment by the surgeon, a dietitian, a physician and usually a psychologist, had an endoscopy and blood tests, and followed a low-calorie diet for two weeks to shrink the liver. You are admitted the day before or on the morning of surgery, fasting, and have a general anaesthetic.

Your surgeon makes four or five small cuts in the upper abdomen and works with a camera and long instruments. The pouch is created with a stapler, the small bowel is divided and brought up to it, and the two joins are made and tested. Most operations take about two hours.

You are sat up and walking the same evening and started on sips of water, often after a swallow test. Expect two to three nights in hospital, and you go home on a liquid diet with written instructions and a follow-up date.

You progress from liquids through pureed and soft food to normal textures over about six weeks, guided by the dietitian, with protein first at every meal and fluids kept separate. Desk work is realistic at two weeks, driving at two to three, and lifting and gym at six.

Weight falls fastest over the first six months and continues to around 18 to 24 months, with most people losing roughly 65 to 80 percent of their excess weight. Type 2 diabetes improves or goes into remission in a large proportion, often within weeks, and your physician will need to reduce diabetes and blood pressure medication early to avoid your levels dropping too low. Follow-up is for life: a daily multivitamin, iron, calcium with vitamin D and vitamin B12 as your team prescribes, with blood tests at intervals. Avoid anti-inflammatory painkillers afterwards, because they cause ulcers at the join.