Weight loss surgery

There are several types of weight loss surgery – also known as bariatric surgery – that can help overweight people lose weight when other options, including diet and exercise, have been unsuccessful.

Weight loss surgery can help you lose 50 per cent or more of your excess weight in 2 years. It can also help treat conditions that are related to obesity, including type 2 diabetes and sleep apnoea. Other benefits include improved mood, self-esteem and quality of life.

About 18,000 weight loss operations were performed in Australia in 2014.

How does weight loss surgery work?

Bariatric surgery can help achieve and maintain significant weight loss by:

  • reducing the amount you can eat;
  • reducing the absorption of calories; and
  • altering the production and release of a hormone related to hunger (ghrelin), resulting in reduced hunger and increased feelings of fullness.

How quickly will I lose weight?

Although the rate of weight loss will vary depending on the type of surgery you have, most people can expect to lose about 4 kg per month to start with.

Who can have weight loss surgery?

In general, surgery for weight loss (bariatric surgery) is an option reserved for people with a body mass index (BMI) greater than 40 kg/m2, or obese people (BMI higher than 30-35) who also have other serious health problems such as diabetes or heart disease.

Weight loss surgery is usually considered only after dietary and medical treatments have failed.

People considering weight loss surgery should be:

  • motivated to lose weight;
  • realistic about their expectations; and
  • willing to commit to both lifestyle modifications and long-term follow-up with their doctor and other health professionals.

Support from family and friends is important if you are considering weight loss surgery.

Can teenagers have weight loss surgery?

Weight loss surgery is sometimes appropriate for adolescents aged older than 15 years. Overweight teenagers should talk with their doctor about whether they are eligible for bariatric surgery, and which type of surgery would be most suitable for them.

What types of weight loss surgery are available?

There are several different types of bariatric surgery available in Australia (see below). The type of surgery that is most suitable for you will depend on factors such as your body mass index (BMI), other health problems, your current eating patterns/habits and the risks associated with each type of surgery.

Gastric banding

Laparoscopic adjustable gastric banding (LAGB), commonly referred to as ‘lap band’ surgery or ‘lap banding’, is done via laparoscopy (keyhole surgery).

A silicone band with an inflatable inner balloon is placed around the upper part of the stomach, which reduces the capacity of the stomach.

How does gastric banding work?

The band ensures you feel full after you have eaten only a small amount of food. The tightness of the gastric band can be adjusted by means of injecting fluid into or out of it through an access device, located under the skin of the abdomen. This adjustment is a simple procedure and can be done on an outpatient basis.

Gastric banding does not affect the digestive processes of the body, so food is still absorbed normally. After gastric banding, you can eat 3 balanced meals a day, although the portions will be smaller than they were before the operation. People need to eat slowly and each mouthful needs to be small and chewed properly before swallowing. You should not drink liquids with meals. It is very important for people who have had gastric banding to continue to follow dietary advice and an exercise programme.

Regular follow-up with your doctor and other health professionals is needed after the procedure, to ensure its effectiveness. The band is designed to remain in place permanently, but can be removed if necessary.

Effectiveness of gastric banding

Gastric banding has been shown to be very effective for weight loss. Research shows that with a good follow-up programme, it can be associated with a decrease of up to 60 per cent of excess weight after 2 years. (Weight is generally lost at a rate of 0.5 to 1 kg per week.)

Complications and side effects of gastric banding

Improvements in surgical techniques have meant complications following lap band surgery are now uncommon. There is a slight risk of the band slipping down the stomach, and very occasionally eroding into the stomach. About 5 per cent of people need a further laparoscopy to manage complications such as these.

Side effects include vomiting and regurgitation if you eat too much or too quickly. Heartburn and other symptoms of gastro-oesophageal reflux can also occur.

Gastric sleeve surgery

Gastric sleeve surgery (also called vertical sleeve gastrectomy) involves permanently removing most of the stomach, so that instead of having a 2 litre capacity, it can only hold about 200 mL. This procedure is performed via laparoscopy (keyhole surgery).

Reducing the volume of the stomach means you can’t eat as much and feel full much faster. Also, removing the part of the stomach that releases the hormone responsible for feeling hungry (ghrelin), means that people feel less hungry and eat less. This procedure is especially helpful for those who have a history of eating very large meals.

Effectiveness of gastric sleeve surgery

This procedure results in rapid weight loss. However, about one in 5 people will regain some of the lost weight over time.

Side effects and complications of gastric sleeve surgery

Complications tend to happen in the first 2 weeks after surgery, and can include leaking from the cut edge of the stomach and bleeding.

Vomiting is uncommon after gastric sleeve surgery.

Gastric bypass surgery

Gastric bypass surgery is an option often recommended for people with a very high BMI. It involves a laparoscopic procedure to:

  • reduce the size of the stomach (to restrict the amount of food that can be eaten); and
  • create a passage for food to bypass the first part of the small intestine (where nutrients – and thus calories – are absorbed).

This operation also alters hormones that affect appetite and metabolism, and makes it difficult to digest sweet foods (eating sugary foods often results in an unpleasant side effect called dumping syndrome).

Effectiveness of gastric bypass

80 per cent of excess weight is expected to be lost within the first year. Weight loss tends to be maintained.

Complications and side effects of gastric bypass

There are some significant complications that can result from gastric bypass surgery, and the risk of death is about 1 in 100.

Dumping syndrome – when food (especially sugar) moves too quickly from the stomach to the small intestine – is a side effect that is associated with gastric bypass surgery. Dumping syndrome causes symptoms of nausea, vomiting, diarrhoea, cramps, anxiety and sweating after eating. Dietary changes can help control dumping syndrome.

Gastric balloon

Placement of a gastric balloon is the least invasive weight loss procedure. It involves having an endoscopy and an inflatable balloon being placed in the stomach and filled with liquid. This restricts the volume of the stomach so that less food can be comfortably eaten.

The procedure is easily reversible – the balloon can simply be removed with a gastroscopy. In fact, this procedure is usually regarded as a temporary weight loss option.

Effectiveness of gastric balloon

Gastric balloon results in an average weight loss of 10 per cent of starting weight after 6 months. The weight loss is maintained in about a third of people.

The balloon needs to be removed or replaced after 6 months.

Complications and side effects of gastric balloon

Nausea, vomiting and abdominal cramps are common in the week after the procedure. In some people, this does not settle, and the gastric balloon needs to be removed.

Serious complications are uncommon.

Comparison of different types of bariatric surgery
Procedure May be suitable for Rate of weight loss Time in hospital Time off work Side effects/ complications Is it reversible?
Gastric balloon Younger people wanting to kick-start weight loss. Very obese people who need to lose some weight to make it safer for them to have a permanent form of weight loss surgery. About 10-15 kg weight loss is common. Most weight loss occurs in the first couple of months after the procedure. Usually done as day surgery About one week Nausea, vomiting and abdominal cramps are common to start with. Serious complications are rare. Easily reversible
Gastric banding People wanting long-term weight loss and a low-risk procedure. Weight is lost gradually over several years Usually requires an overnight stay in hospital Up to one week Gastric banding has a low rate of complications during and after the procedure, but the band may need adjusting in a subsequent procedure. Reversible
Gastric sleeve Those with a higher starting weight and health problems related to obesity needing a long-term weight loss option. Weight is lost quickly, with most lost in the 1-2 years after the procedure. About 2-3 nights in hospital About 2 weeks Most serious complications happen in the first 2 weeks after surgery. Late complications are rare. Not reversible
Gastric bypass Those with a higher starting weight and health problems related to obesity needing a long-term weight loss option. Weight is lost quickly, with most lost in the 1-2 years after the procedure. 2-4 nights in hospital About 2 weeks Complications are more common with this procedure. Ask your doctor about the risks. Reversal is possible, but can be difficult

Is there any preparation needed before weight loss surgery?

Your doctor will let you know what preparations are needed, depending on the type of surgery you are having.

You will probably be referred to a dietitian before your surgery to get advice on healthy eating. You’ll also need to improve your levels of physical activity. Some people are referred to a psychologist or counsellor to address their eating habits before surgery.

A very low-calorie diet is usually prescribed for at least 2 weeks before the surgery to help reduce the chance of complications. This usually means having meal replacement shakes.

Can I eat normally after weight loss surgery?

Immediately after your surgery, you won’t be able to have anything to eat for a few days. After starting on liquids, you’ll move to pureed food, then a soft diet and then solid foods.

Long-term, you won’t be able to eat the same amount after your weight loss surgery. Small portions are essential, and you usually need to eat slowly, chewing your food well. Eating small meals on a regular basis is often recommended. It’s also important to choose nutritious meals to reduce nutrient deficiencies.

Will I need to take vitamins after having weight loss surgery?

After most types of bariatric surgery, your doctor will recommend you take regular vitamin and mineral supplements. This is because the surgery can affect your ability to absorb sufficient nutrients from food. When you don’t absorb adequate amounts of nutrients, you can develop problems such as anaemia or osteoporosis.

Recommended supplements typically include:

  • iron;
  • vitamin B12;
  • folic acid;
  • calcium;
  • vitamin D;
  • zinc; and
  • thiamine (vitamin B1).

Regular blood tests are usually recommended to test your levels of key nutrients to ensure that you are not deficient. Lifelong vitamin and mineral supplementation is generally needed.

Can weight loss surgery be reversed?

Some weight loss surgery procedures can be reversed, but others can’t. Make sure you understand beforehand whether there is an option for you to have the procedure reversed.

Will I need ongoing treatment and follow-up?

It’s recommended that people who have had weight loss surgery have lifelong follow-up. Follow-up involves:

  • checking on your weight;
  • ensuring you do not have any nutritional deficiencies;
  • checking for side effects; and
  • checking you are taking any prescribed nutritional supplements.

Do I need to change my lifestyle to maintain weight loss?

Weight loss surgery restricts the amount of food you can eat, but it’s also important that you eat foods that are nutritious and not too high in calories. Getting enough physical activity (at least 30 minutes on most days) is also important for continuing weight loss and maintaining weight loss.

Your doctor and other members of your health care team will give you advice on how to reach your weight loss goal and keep the weight off.

Does weight loss surgery always work?

Some people find that they don’t lose as much weight as they expected following weight loss surgery, while others may regain some of the lost weight.

It’s very important that you have ongoing follow-up with your doctor and other health professionals involved in helping you to lose weight.

Long-term lifestyle changes, such as increased physical activity and eating a healthy diet, are essential in losing weight and maintaining weight loss, even after you’ve had weight loss surgery.

Author: myDr


1. National Institute of Diabetes and Digestive and Kidney Diseases. Bariatric surgery (updated July 2016). https://www.niddk.nih.gov/health-information/health-topics/weight-control/bariatric-surgery/Pages/all-content.aspx (accessed Sep 2016).
2. National Health and Medical Research Council (NHMRC). Clinical Practice Guidelines for the management of overweight and obesity in adults, adolescents and children in Australia (2013). https://www.nhmrc.gov.au/guidelines-publications/n57 (accessed Sep 2016).
3. Australian Diabetes Council Bariatric Surgery Position Statement (produced 2012; updated June 2013). http://diabetesnsw.com.au/wp-content/uploads/2014/11/Bariatric-Surgery-Position-Statement.pdf (accessed Sep 2016).
4. Grima M, Dixon JB. Obesity: recommendations for management in general practice and beyond. Australian Family Physician (AFP) 2013: 42 (8): 532-41. http://www.racgp.org.au/afp/2013/august/obesity/ (accessed Sep 2016).


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