Gastric Bypass Surgery

The Gastric Bypass is a surgically proven form of weight loss. Patients can expect to lose 66-75% of their excess body weight in the first two years following surgery (source: BOSPA).

Gastric bypass operations are a surgically proven  form of weight loss when combined with a supervised diet, physical activity and behaviour modification programme.  They are generally recommended for patients with higher BMI i.e. a Body Mass Index of 40 or over.

There are several varieties of bypass, but all involve the creation of a small stomach pouch to restrict food intake and reduce the absorption of calories and nutrients from food which causes effective weight loss results.

Gastric Bypass Procedures

  • Restrictive and malaborpative
  • Restricts the amount you can eat
  • Calories and nutrients not fully absorbed
  • Dumping syndrome common
  • The Gateway Programme – Reduces hunger and cravings enabling you to work on lifestyle change.

There are 3 main types of Gastric Bypass procedure, both of which essentially reduce the size of the stomach pouch so that less food is absorbed.

1. Roux-en-Y Gastric Bypass (RGB)

With this procedure a small stomach pouch is created by stapling part of the stomach together or vertical banding. This limits how much food you can eat. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum as well as the first portion of the jejunum.  This is demonstrated below:

2. Biliopancreatic diversion Gastric Bypass (BPD)

In this more complicated version, portions of the stomach are removed and the small pouch that remains is connected directly to the final segment of the small intestine. This means that most of the small intestine (duodenum and jejunum) is bypassed, resulting in substantial reductions in calorie and nutrient absorption.

3. Sleeve gastrectomy

Sleeve gastrectomy is a surgical weight-loss procedure in which the stomach is reduced to about 15% of its original size, by surgical removal of a large portion of the stomach, following the major curve. The open edges are then attached together (often with surgical staples) to form a sleeve or tube with a banana shape. The procedure permanently reduces the size of the stomach. The procedure is performed laparoscopically and is not reversible.

Frequently Asked Questions (FAQ)

We have listed here some of the more commonly asked questions from our patients about the Gastric Bypass procedure.

Q: How do I know if I’m suitable for a gastric bypass?

Usually patients most suitable to have a gastric bypass are those with a BMI in the range of 40 to 60+. However surgery is dependent upon a specialist nurse opinion, who will then discuss your case with a specialist surgeon.  All of our weight-loss surgery patients have an in depth consultation to discuss the most relevant procedure for them, prior to surgery.

Q: What are the benefits of gastric bypass?
For the seriously obese, the benefits of the gastric bypass procedure very much outweigh the risks. In general:

  • 75% of patients are expected to lose 75 to 80% of their excess body weight, most of which is lost in the first two years following surgery.
  • Major improvements in risk factors for heart disease and cancer.
  • Around 70-80% of patients with hypertension will be off medication and cholesterol levels will fall.
  • Most type II diabetics will be cured.
  • There will be major improvements in a whole range of weight-associated conditions. These could include sleep apnoea, asthma, joint pain, arthritis, reflux, fatigue, shortness of breath.
  • Patients report less depression, improved self-esteem and confidence along with an overall increased sense of well-being.


Q: What are the risks of gastric bypass?
As with any surgery, there are operative and long-term complications and risks associated with gastric bypass, including:

  • Bleeding (haemorrhage).
  • Complications due to anaesthesia and medications.
  • Infections.
  • Pulmonary emboli (blood clots on the lung).
  • Deep vein thrombosis.
  • Dehiscence (wound breakdown).
  • Leaks from staple line.
  • Injury to the spleen.
  • Marginal ulcers.

However, in experienced hands the risks of the procedure nowadays are very small. Most published reports show that the overall mortality rate for gastric bypass surgery is less than 1%. It’s also important to note that not only does bypass result in reduced absorption of calories, it may also reduce absorption of important vitamins and minerals such as iron, vitamin B-12 and calcium. Deficiencies in these nutrients can lead to many problems. Iron deficiency causes anaemia and weakness and deficiencies in calcium can cause osteoporosis. Lack of daily B-12 can lead to neurological problems. This is why patients undergoing gastric bypass are recommended to take a daily vitamin and mineral supplement. “Dumping syndrome,” in which the consumption of sugar causes abdominal cramping and diarrhoea, can also occur. Some people will also regain some weight in subsequent years.

Q: How long will I be in hospital?
For open operations, most patients are discharged on the third or fourth post-operative day. Patients who have the laparoscopic procedure can go home on the second or third post-operative day.

A word of caution
Although there is no doubt that surgery can be both life-transforming and life-saving, the decision to go ahead with surgery is a serious one. Any general anaesthetic involves a measure of risk and individuals with serious degrees of obesity are at greater risk than their non-obese counterparts. You should ensure that the surgeon you choose is experienced and that full specialist advice is available at the clinic you choose. The choice of surgeon is crucial. This is not a procedure for the general surgeon. It should only be carried out by those who are specially trained in the surgery of the upper abdomen (upper GI surgeons).

The Need for Long-Term Follow Up
An important thing to remember is that surgery is not a cure for obesity. It is not a magic wand and will not guarantee results without complete dedication by yourself and by your nurse.

If you are going to be successful you will have to continue to work on the behaviours which are important for anyone attempting to lose weight, including physical activity, reducing portion sizes, avoiding energy-dense foods etc.

For this reason, you should ensure the hospital of your choice has available a structured, long-term behavioural and lifestyle programme, with nutritional advice, which you should follow immediately after surgery.