Prof. Dr. Emin Ersoy General Surgery
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Surgical Methods

Gastric Bypass Surgery

A walnut-sized stomach pouch is joined straight to the small intestine, so you eat less and absorb fewer calories and less fat.

BMI 40+ · 35-40 with e.g. type 2 diabetes

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Overview of gastric bypass surgery

Gastric bypass surgery, also called a Roux-en-Y gastric bypass, is a weight-loss operation in which the stomach is made into a small pouch that is joined directly to the small intestine. The aim is to reduce both the amount of food you eat and the amount of fat and calories your body absorbs. It is one of the established types of bariatric surgery.

A small pouch, about the size of a walnut, is formed from the upper part of the stomach. The small intestine is then divided and one section is stitched directly to this pouch. Food passes first into the small pouch, so you feel full sooner, and then straight into the small intestine. Because it no longer passes through the duodenum (the first part of the small intestine), some of it is not absorbed. This combination of a smaller stomach and a shorter route for food is what makes a gastric bypass different from a gastric sleeve, in which the route of food through the intestine stays the same.

Who is it for?

A gastric bypass is recommended for people who are overweight or living with obesity, who have not lost enough weight despite changes to diet and exercise, and who have health problems linked to their weight. You may be suitable if:

  • your BMI (body mass index) is 40 kg/m² or higher, or
  • your BMI is between 35 and 40 kg/m² and you have an obesity-related condition such as type 2 diabetes, high blood pressure or severe sleep apnoea, or
  • your BMI is above 30 kg/m² and you have type 2 diabetes or severe metabolic problems.

Your doctor will decide whether the operation is right for you after a thorough assessment. Part of this assessment is looking at the conditions linked with obesity, because a gastric bypass can lower your risk of them. These include:

  • reflux disease (GORD)
  • heart disease
  • high blood pressure
  • high cholesterol
  • sleep apnoea
  • type 2 diabetes
  • stroke
  • infertility

If type 2 diabetes is your main concern, you can read more on the diabetes surgery page.

Risks

Like any major operation on the abdomen, gastric bypass surgery carries general risks, such as bleeding, infection, reactions to the anaesthetic, blood clots in the legs and a leak where the stomach pouch or the bowel has been joined. There are also drawbacks that are more specific to this operation:

  • Compared with other stomach-reducing operations, a gastric bypass is technically more complex.
  • In the long term, it can lead to a lack of vitamin B12, iron, calcium and folate. For this reason, you will need to take vitamin and mineral supplements for life.
  • Dumping syndrome can develop: after eating, especially very sugary food and drinks, you may feel unwell, sick and have a headache. Avoiding very sugary foods can help prevent this.

Knowing about these drawbacks in advance is part of making the decision. Most of the long-term ones can be managed by taking your supplements and following the eating advice you are given.

Preparation

Before a gastric bypass, you will have a thorough medical assessment to find out whether the operation is suitable for you. This usually includes blood tests and other tests if needed, and advice from a dietitian. Depending on your health, you may also be seen by other specialists, such as a heart, lung or hormone specialist, and a psychological assessment may be offered to help you prepare for the changes after the operation.

Your medicines are reviewed with you before the operation. Blood-thinning medicines and some other medicines may need to be stopped for a while, and you will be told which ones to keep taking. You will be asked not to eat or drink for a set time beforehand. If you smoke or drink alcohol, you will be advised to stop, and it helps to arrange support at home for when you leave hospital. The possible risks and benefits are discussed with you, and you give your written consent.

What happens

On the day

A gastric bypass needs a hospital stay, usually of 3 to 5 days. The operation is done by keyhole (laparoscopic) surgery under general anaesthesia, so you are asleep throughout. The stomach is reached through small cuts in the abdomen, and the surgeon works with special instruments while watching an enlarged image from a camera on a screen. First the small stomach pouch is formed, and then a section of the small intestine is joined to it.

After the operation you are looked after until you are fully awake. You will be encouraged to get up and move soon, because this helps your recovery and lowers the risk of blood clots.

Aftercare

Your diet after gastric bypass surgery is built up in several stages. Your doctor will decide how long each stage lasts and what you can eat. You will also learn how to control your portions and how to eat well in the long term.

  1. Clear fluids: for the first few days, you drink only a few sips of clear fluid at a time. This lets the stomach heal without being stretched by food.
  2. Puréed food: when your doctor feels you are ready, you move on to the second stage. Many foods can then be eaten blended to a purée. Spices can cause discomfort, so avoid them completely. Avoid fruit with a lot of seeds, such as strawberries or kiwi, and very fibrous foods, such as broccoli or cauliflower, that cannot be blended smoothly enough.
  3. Soft food: after a few weeks, soft foods that are easy to chew are added.
  4. Solid food: about two months after the operation, solid food is reintroduced. Cut food into small pieces, because larger amounts can cause a blockage, which leads to pain, nausea and vomiting.

Taking vitamin and mineral supplements is important at every stage and for the rest of your life, because the part of the intestine that food now bypasses is where some of these nutrients are normally absorbed. As part of your follow-up, a routine blood test check is done at 6 months to make sure that your diet and supplements are working for you.

When should you contact your doctor?

Contact your doctor or the hospital straight away if, after you go home, you have:

  • a high temperature or shivering (chills)
  • increasing pain or swelling in the abdomen
  • nausea or vomiting that does not stop
  • redness, swelling or fluid leaking from any of the cuts
  • shortness of breath or a persistent cough
  • swelling of the calf or tenderness in the leg

Frequently asked questions

How does a gastric bypass work?

A small pouch, about the size of a walnut, is made from the upper stomach and joined directly to the small intestine. You eat less, and because food bypasses the duodenum, some of it is not absorbed.

Who is a gastric bypass for?

It may be suitable if your BMI is 40 kg/m² or higher, between 35 and 40 kg/m² with a condition such as type 2 diabetes, high blood pressure or severe sleep apnoea, or above 30 kg/m² with type 2 diabetes or severe metabolic problems.

How long will I stay in hospital?

A gastric bypass usually needs a hospital stay of 3 to 5 days.

Do I need to take vitamins after a gastric bypass?

Yes. A gastric bypass can lead to a lack of vitamin B12, iron, calcium and folate, so you need vitamin and mineral supplements for life.

What is dumping syndrome?

After eating, especially very sugary food and drinks, you may feel unwell, sick and have a headache. Avoiding very sugary foods can help prevent it.

When can I eat solid food again?

Solid food is reintroduced about two months after the operation, after the clear fluid, puréed and soft food stages.

Would you like to discuss this?

The right method for you is decided together after examination and tests. You can start with the pre-assessment or call directly.

Request an appointment +90 533 300 35 75

Other methods in this group

Gastric Sleeve Surgery About 80% of the stomach is removed by keyhole surgery, leaving a narrow tube that holds less food and makes less hunger hormone. BMI 40+ · 35-40 with related conditions Learn more › Bariatric Surgery Keyhole operations on the stomach and small intestine, such as the gastric bypass, for severe obesity that other treatments have not helped. Severe obesity · other treatments failed Learn more › Diabetes Surgery Keyhole operations on the stomach and small intestine that act through gut hormones such as GLP-1 in type 2 diabetes. BMI 30+ with type 2 diabetes Learn more ›

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