Gastric bypass surgery

Gastric bypass surgery is an operation to help you lose weight and improve weight-related health problems if you’re . It makes your stomach smaller and bypasses part of your bowels (intestines). This changes the signals between your bowel and your brain that control your appetite, how full you feel, and your weight.

About gastric bypass surgery

Gastric bypass surgery can help you lose up to two-thirds of your excess weight within two years. And you should be able to keep most of this weight off long-term. But this will depend on committing to some changes to your lifestyle after the operation. For example, you’ll need to:

• change your diet – stop snacking and choose healthier options
• not drink too much
• take

Your doctor will talk through these changes with you.

Who can have gastric bypass surgery?

Your doctor may refer you to a specialist weight-management service to discuss your options. A specialist team that includes a surgeon, dietician and psychologist will assess you to see if gastric bypass surgery is the right operation for you. You may be offered weight loss surgery if you:

• have a body mass index (BMI) of 40 or more
• have a BMI of 35 to 40 and a condition such as  or  which could get better if you lose weight
• are fit enough to have an anaesthetic and surgery
• are committed to having long-term follow-up appointments and changing your lifestyle and diet after your operation
• are over 18 (although children are considered in exceptional circumstances)

You’ll usually only be considered for surgery if you’ve tried to lose weight in other ways and this hasn’t worked.

Preparation for gastric bypass surgery

Your hospital will let you know how to prepare for your operation.

If you , you’ll be asked to stop at least six weeks before the operation. Smoking increases your risk of complications of surgery.

Your surgeon will usually ask you to eat a low-, low-diet for two weeks before surgery to shrink your liver, which will allow your surgeon better access to your stomach.

You’ll have gastric bypass surgery under (GA), which means you’ll be asleep during the operation. You won’t be able to eat for about six hours before surgery, but you may be able to drink water up until two hours before. If you’re asked to follow fasting instructions, always follow your surgeon’s advice.

You’ll be asked to wear compression stockings on your legs to help prevent blood clots forming in the veins in your legs (). You’ll also need to have an injection of an anti-clotting medicine as well as or instead of wearing compression stockings.

Your surgeon will discuss with you what will happen before, during and after your surgery at various stages. If you’re unsure about anything, don’t be afraid to ask. No question is too small. It’s important that you feel fully informed so you feel happy to give your consent for the operation to go ahead. You’ll be asked to do this by signing a consent form.

Gastric bypass surgery

A gastric bypass operation usually takes around one to two hours, although this can vary between hospitals. It’s usually done using keyhole (laparoscopic) surgery, which means your surgeon makes small cuts in your tummy rather than one large cut. They’ll use small instruments, guided by a telescope with a camera. Sometimes your surgeon may need to switch from keyhole surgery to open surgery during the procedure.

Your surgeon will use surgical staples to make a pouch out of the top of your stomach, separating it from the lower part. They’ll then make an opening in the pouch and connect it to a section of your small bowel. This means the food you eat won’t pass through the lower part of your stomach or the first part of your bowel. Your surgeon will bypass a carefully selected amount of bowel. This means that when you reach the right weight, you’ll be able to absorb enough nutrients from your food.

Your surgeon will close your cuts with stitches or small metal clips and place a dressing over your wounds.

Aftercare for gastric bypass surgery

In the hospital

You’ll need to rest until the anaesthetic has worn off. But it’s important to get out of bed and move around as soon as you can. This will help you to recover and prevent blood clots developing in your legs. You may also need pain relief.

Your hospital may give you something to help prevent deep vein thrombosis (DVT). For example, you may have to wear pads attached to an intermittent compression pump on your lower legs to boost the blood flow in your legs. Or you may need to wear compression stockings to help boost your circulation and continue to have injections of an anti-clotting medicine such as heparin.

You’ll have a drip put into a vein in your hand or arm to give you fluids. If you feel well enough, you can start to drink small amounts of water soon after your operation, and a nurse will remove the drip.

Going home

You’ll usually be able to go home around two days after your operation. Ask a friend or family to drive you. Your nurse will tell you how to  before you go home and will give you a date for a follow-up appointment. You may need to take painkillers for a few days after the operation.

It will probably take around three weeks to recover from a keyhole gastric bypass operation. You’ll usually go home on a liquid diet – your surgeon will give you advice on how to move on from this. For more information, see our section on lifestyle changes and our FAQ: What can I eat after surgery?

Lifestyle changes after surgery

You’ll need to make major changes to what you eat after gastric bypass surgery because the volume of your stomach will be smaller. You’ll usually need a liquid diet when you first get home. You can then move on to puréed food, mashed food, and then small solid meals during the first four to six weeks after your operation. For more information, see our FAQ: What can I eat after surgery?

It’s essential to make these changes to your diet after surgery. You also need to make sure that you get enough protein, vitamins and minerals, which can affect your health. If you don’t get enough iron, it may cause anaemia, for example. You’ll need to take vitamin and mineral supplements for the rest of your life. You may also need to have regular vitamin B12 injections and have regular blood tests to check you’re getting everything you need.

You’ll need to do more exercise and drink less alcohol too. This will help you to get the most from your gastric bypass operation, so you can lose excess weight and keep it off.

Losing weight after a gastric bypass is usually a positive thing. But you may find it hard to adapt to your lifestyle and appearance after the operation. Talk to your GP or surgeon if you’re struggling to cope. They may suggest a patient support group, where you can get advice from other people who have been through the operation too.

Side-effects of gastric bypass surgery

You may have some bruising, pain and swelling around your wounds after a gastric bypass. But this shouldn’t last too long.

You may feel sick or even be sick after eating. This is because you’ll only be able to eat a small amount of food at a time. This should get better with time as you get used to eating smaller amounts.

You may get an unpleasant sensation called dumping if you eat too many sugary foods. For more information, see our FAQ: What is dumping?

Alternatives to gastric bypass surgery

Other types of surgery can help you lose excess weight. These include sleeve gastrectomy and . Like gastric bypass surgery, you’ll need to make long-term changes to your diet and lifestyle for them to work.

Another option is to have a silicon balloon inflated in your stomach. This will make you feel full but it can only be used for short-term weight loss.

Ask your surgeon about the options available – they’ll help you decide which one is best for you.

Frequently asked questions

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