Gastric Bypass Surgery

Gastric bypass surgery, also known as Roux-en-Y gastric bypass, is a more complex weight-loss procedure that involves creating a small stomach pouch and rerouting part of the digestive system.

Incision and access

The surgery is typically performed laparoscopically, which means it’s done through several small incisions (around 5) rather than one large incision. The surgeon inserts a laparoscope (a small camera) and surgical instruments through these incisions.

Creating a small stomach pouch

The surgeon divides the stomach into two sections: a small upper pouch and a larger lower portion (called the bypassed stomach). The small stomach pouch, about the size of a walnut (roughly 1 ounce or 30 millilitres in volume), will be the only part of the stomach that receives food. This drastically reduces the amount of food a person can eat at one time.

Rerouting the small intestine

The surgeon cuts the small intestine and connects it directly to the small stomach pouch. This new connection is called a Roux limb. The rest of the stomach and the first part of the small intestine (the duodenum) are bypassed, meaning that food does not pass through them anymore.

The surgeon then reconnects the bypassed portion of the small intestine (further down) to the lower section of the small intestine, allowing digestive juices from the bypassed stomach and the first part of the small intestine to mix with food. This connection ensures that some digestion and absorption still occur.

The weight loss achieved continues for 12 to 18 months.

On average, patients can expect to lose approximately 75–80% of their excess weight (a term used to describe weight above a BMI of 25) after their gastric bypass procedure.

Typically, that’s 30–35% total body weight over a period of 9 to 12 months.

Patients are usually up and walking within three hours of gastric bypass surgery and are able to drink liquids straight away.

The average postoperative hospital stay is one to two nights. Patients can expect to return to work after 7 to 10 days and to full activity within 10 to 14 days of surgery.

As patients will be eating small meals, they will be required to take vitamins and minerals to avoid deficiencies. These include calcium (with vitamin D), iron, multivitamins and three-monthly vitamin B12 injections. Blood tests are recommended every 6 to 12 months to ensure adequate supplementation. PPI (anti-acid) tablets can be discontinued after two years unless you are taking non-steroidal anti-inflammatory medication (e.g. ibuprofen). Women of child-bearing age, including infertile women with polycystic ovary syndrome, are advised to practise contraception for 12 to 18 months after surgery.

Preparing for a gastric bypass

The Tonic team will be in touch before and after surgery to advise about appropriate preparations and aftercare.

Patients will often need to go on a liver-shrinking diet (800 calories a day), for around two weeks before surgery. After the operation, patients will be advised to go on a specialist diet to help with the healing process. This involves a liquid diet for two weeks, a puréed diet for one to two weeks and soft, easy-to-chew foods for one to two weeks.

Following your gastric bypass surgery, you should expect...

The small stomach pouch can only hold a tiny amount of food, so you’ll feel full much faster and with much smaller portions. Since part of the small intestine is bypassed, fewer calories and nutrients are absorbed, which contributes to weight loss.

This malabsorption also affects how vitamins and minerals are absorbed, which means you’ll be required to take supplements long-term to prevent deficiencies.