What is gastric bypass surgery?

Gastric bypass is a type of bariatric surgery — a weight loss surgery that can help people with obesity to lose weight and improve their health. Gastric bypass surgery makes your stomach smaller and connects it directly to your small intestine, bypassing part of your digestive tract.

There are two types of gastric bypass:

• Roux-en-Y gastric bypass — where the digestive tract is sewn together in 2 different places
• single anastomosis or 'mini' gastric bypass (the more common type) — where the digestive tract is sewn together in only one place

Making your stomach smaller causes you to feel full after eating less. Bypassing part of your digestive tract means that your small intestine doesn't absorb food as well. Together, these effects make it easier for you to lose weight.

Visit our guide to bariatric surgery to learn more about the different types of bariatric procedures.

What are the benefits of bariatric gastric bypass surgery?

A gastric bypass tends to lead to a larger amount of weight loss than other bariatric surgeries. It also has good long-term weight loss results.

Losing weight after gastric bypass surgery can help:

• control type 2 diabetes
• lower blood pressure
• improve heart health
• improve your quality of life

When might I consider gastric bypass surgery?

You might consider gastric bypass surgery if you have tried to lose weight by dieting and doing more exercise and have not reached a healthy weight.

Your doctor might suggest having a gastric bypass to help with weight loss if:

• you have a body mass index over 40
• a body mass index over 35 with other serious health problems associated with obesity, such diabetes or heart disease

Gastric bypass surgery is a very effective type of surgery for weight loss, but it is not for everyone. You should discuss with your doctor which approach is best for you and talk about what to expect.

How do I prepare for gastric bypass surgery?

If you are planning to have surgery, your doctor will refer you for tests to make sure that a gastric bypass is right for you. You may be asked to attend an information session to learn more about the surgery and what to expect afterwards.

Smoking affects your recovery after surgery and can increase your risk of experiencing complications. If you are a smoker, it's strongly recommended to quit at least 6 weeks before you have gastric bypass surgery.

To lower your risk of complications, it's recommended to eat a very limited diet for several weeks before having surgery. Your doctor will tell you more about any changes you need to make to your medicines and diet in the weeks and days before surgery.

What should I expect during gastric bypass surgery?

Gastric bypass surgery is performed while under general anaesthetic. It is usually done as a keyhole (laparoscopic) procedure. Sometimes, an open operation is needed.

During the procedure, staples are used to create a small pouch in the top part of the stomach, as shown in the image below.

The pouch is attached to the lower part of the small intestine, so food will bypass most of the stomach and the first part of the small intestine.

What can I expect after the procedure?

Most people will stay in hospital for 2 to 3 days after the procedure. You might need to take pain medicine for a short time after the surgery and you may be advised not to drive.

If you have had gastric bypass surgery, at first you will be on liquid food only. You will then gradually transition to pureed food and then solids after a few weeks.

A dietitian will advise you how you can change your eating habits after gastric bypass surgery to keep healthy while losing weight. Physical activity is also important after gastric bypass surgery. A physiotherapist can guide you how to gradually build up your level of exercise.

You might find that you initially lose weight, but then your body becomes used to the changes made during the surgery. To maintain weight loss in the long term, it's important to follow your healthcare team's advice and discuss any concerns.

You will need regular health checks and blood tests for the rest of your life following surgery. You will also need to take vitamin and mineral supplements for life to replace those normally absorbed in the first part of the small intestine.

If you take medicines, they may need to be adjusted after surgery, so be sure to see your doctor regularly.

What are the risks of gastric bypass surgery?

Risk of gastric bypass surgery can include:

• bleeding or leaks from the staple line or joins
• bowel obstruction
• nutrient and vitamin deficiency
• dumping syndrome (a range of symptoms after carbohydrate-rich meals)
• low blood sugars

As with any surgery, there is a risk of infection or that the surgery does not work. You should talk to your doctor about the risks of the procedure.

Resources and support

Speak to your doctor if you have any questions about your weight or if you are interested in finding out about gastric bypass surgery.

You can check your eligibility for bariatric surgery on the Queensland Government website.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

The Australian dietary guidelines can help you find healthy eating tips for both before and after surgery.

For help to quit smoking call Quitline on 13 7848 (13QUIT). Hours of service my vary between states and territories, so can check the website for details or request a call back.

Do you prefer to read in languages other than English?

You can also find information on smoking cessation and healthy eating on the Health Translations or Multicultural Health Communication Service websites for resources in languages other than English.

Looking for information for Aboriginal and/or Torres Strait Islander people?

Aboriginal Quitline is staffed by Aboriginal counsellors. You can call them on 13 7848 if you need help to quit smoking.