How weight loss surgery is performed 

The two most widely used types of weight loss surgery are gastric banding, based on restriction, and gastric bypass, which uses a combination of restriction and malabsorption.

Each type of surgery is discussed in more detail below.

Gastric banding

Gastric banding is usually performed as a type of laparoscopic (keyhole) surgery, where a series of small incisions are made in the abdomen, rather than one large incision. The advantage of this type of surgery is it causes less pain afterwards and has a faster recovery time.

However, laparoscopic surgery may not always be possible in severely morbidly obese people.

Gastric banding is carried out under general anaesthetic, which means you will be asleep during surgery and will not feel any pain.

The surgeon makes the incisions in your abdomen and then inserts an instrument known as a laparoscope through one of the cuts. A laparoscope is a thin, rigid tube containing a light source and a camera. The camera relays images of the inside of your abdomen to a television monitor.

Other small instruments are placed through the cuts to place the band around your stomach, effectively dividing your stomach into two, leaving a small pouch at the top of the stomach.

It will take less food to fill the pouch, so it will take less food to make you feel full.

The band contains an access port through which saline (sterile salt water) can be passed to inflate the band. This allows the band to be adjusted as required after surgery.

The surgery usually takes around an hour to complete.

Gastric bypass

Gastric bypass is usually performed as a type of laparoscopic surgery where possible, as this causes less pain afterwards and has a faster recovery time.

However, it may not be suitable for severely morbidly obese people.

As with gastric banding, a small pouch is created at the top of your stomach. This pouch is then connected directly to a section of your small intestine, bypassing the rest of the stomach and bowel.

This means that it will take less food to make you feel full and you will also absorb fewer calories from the food you eat.

Bypass or banding?

Both types of surgery have advantages and disadvantages.

There is usually more weight loss after a gastric bypass than after a gastric band.

Most people with a gastric band will lose around half their excess body weight, whereas most people with a gastric bypass will lose around two-thirds of the excess body weight.

However, because it is more technically demanding, a gastric bypass carries a higher risk of complications, including death.

The risk of any sort of complication after a gastric band is around 1 in 10 compared to 1 in 5 for a gastric bypass.

The risk of death after a gastric band is around 1 in 200 compared to 1 in 100 for a gastric bypass.

A gastric band is reversible, so if you find it difficult to cope with the restrictions associated with life after surgery, you can have the band removed.

A gastric bypass, on the other hand, cannot be reversed. You will also be required to take nutritional supplements for the rest of your life if you have a gastric bypass.

Discuss the advantages and disadvantages of both types of surgery with your surgical team.

Other types of bariatric surgery

Other types of weight loss surgery, which are less commonly used, are outlined below.

Sleeve gastrectomy

A sleeve gastrectomy is a type of surgery used to treat extremely morbidly obese people (with a BMI of 60 or above).

Such a high level of obesity means that performing a gastric band or bypass would not be safe as both procedures carry a very high risk of causing complications in people of that weight.

During surgery, a section of the stomach is surgically removed, reducing the size of the stomach by three-quarters. The short to medium term weight loss should be around 60-70%.

Once this weight loss has been achieved, it should be possible to perform either a gastric band or bypass safely.

Bilo-pancreatic diversion

A bilo-pancreatic diversion is similar to a gastric bypass except a much larger section of the small intestine is bypassed, meaning you will absorb even fewer calories from the food you eat.

A bilo-pancreatic diversion can achieve a good level of weight loss (up to 80% of excess body weight) but it carries a high risk of complications and can cause unpleasant side effects, such as unpleasant-smelling diarrhoea.

Because of this, a bilo-pancreatic diversion is usually only recommended when it is felt that rapid weight loss is required to prevent a serious health condition, such as heart disease, from getting worse.

Intra-gastric balloon

An intra-gastric balloon is a soft silicone balloon that is surgically implanted into your stomach. The balloon is filled with air or saline solution (sterile salt water), and so takes up some of the space in your stomach. This means you do not need to eat as much before you feel full.

This procedure is only temporary, and the balloon is usually removed after six months. The procedure is useful if you do not meet the criteria for the other types of surgery, for example because you are too obese.

An intra-gastric balloon procedure can usually be done without making an incision in your abdomen. Instead, the balloon can be passed through your mouth and down into your stomach using an endoscope (a thin, flexible tube that has a light and a camera on one end). Read more information about a gastroscopy.

Pre-operative assessments

Before an operation, you will be asked to do a pre-operative assessment. Find out what this involves and how it helps reduce any risks during your operation.

Media last reviewed: 14/11/2013

Next review due: 14/11/2015

Compare your options

Take a look at a simple guide to the pros and cons of different treatments for weight loss surgery

Page last reviewed: 05/05/2013

Next review due: 05/05/2015