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Clinical guidelines in the UK state that weight reduction surgery should be available for:

  • people who have a BMI of 40 or over,
  • or for people with a BMI of 35-40 who have other significant disease such as type 2 diabetes or high blood pressure that could be improved if they lost weight.

In the above cases, other criteria must be fulfilled which are:

  • non-surgical options such as lifestyle interventions or medication must have been tried for at least 6 months, and failed to produce or maintain sufficient weight loss
  • the person must receive intensive management within a specialist obesity service
  • the person must be fit to undergo anaesthetic and surgery
  • the person must commit to long term follow up

Weight reduction surgery is also recommended as a first line option (instead of medication or lifestyle interventions) for people with a BMI of more than 50.

Taken from NICE guideline CG43 on the use of bariatric surgery


There are two main types of surgery:

Restrictive surgery

This can involve removing part of the stomach, or putting a tight band around the stomach, so that you feel full without eating as much.

This type of surgery still relies on you eating sensibly if it is to work. Eating smaller amounts of food but choosing things that are high-fat and/or high-sugar will stop you from losing weight.

It is also important that, if you are only eating small quantities of food, you chose food high in vitamins and other important nutrients, to keep the rest of your body healthy.


Malabsorptive surgery

This type of surgery involves bypassing part of your digestive system, so food is not properly digested and fewer nutrients are absorbed from the food you eat.


Both types of surgery have the potential for serious side effects, including internal bleeding and severe infections. These can lead to a need for further surgery and, in some cases, death.

Surgery is, therefore, not a quick fix or an easy option but, for someone who is extremely obese, should be considered.

See the BOSPA (the British Obesity Surgery Patient Association) website for more information on surgical options.


Benefits of weight loss surgery

Research shows that both types of surgery usually result in people losing about 50 per cent of their excess weight; in many cases this can be up to 65 to 70 per cent of excess weight lost.

This can lead to great improvements in quality of life and reduction in weight-related illnesses. In the long term, people who have had successful bariatric surgery are less likely to develop conditions such as diabetes or high blood pressure than people who remain obese.


Risks of weight loss surgery

Weight loss surgery is not to be considered lightly. There are some very serious risks associated with the surgery itself, as well as complications that may develop afterwards.

Any major surgical operation carries the risk of dying during or after the surgery. With obesity surgery this risk is small – less than 1 in every 100 people, depending on the type of procedure you have.

Other possible risks to bear in mind are:

  • your surgical wounds may become infected
  • you may develop hernias, ulcers and gallstones
  • you may start to suffer from heartburn and constipation
  • you could develop severe nutrient deficiencies, which could lead to undernourishment and possibly bone disease
  • you may be left with excess skin around the stomach
  • you may lose your hair (this is usually only temporary)

It is important to note that if you develop any of these complications, you may need to have further surgery.

Your surgeon should explain in detail all the risks and benefits associated with the surgical option he/she is suggesting. It is important that you ask questions and address any concerns you have before agreeing to the treatment. For some people the benefits of surgery will outweigh the risks.


Important issues to consider about your diet after surgery

It is important to be aware that after surgery you will need to make changes to your diet for life if you are to lose weight and minimise discomfort, unpleasant side effects and the need to have further surgery. In other words, what and how you eat and drink will change forever after weight loss surgery.
For example:

  • You will only be able to eat very small meals for the rest of your life – equivalent to eating from a saucer.
  • You will need to take vitamin and mineral supplements for the rest of your life.
  • You will need ongoing visits to see various specialists, including a dietitian, for life. He/she will be checking that your diet is as balanced as it can be so that you can limit the chances of developing bowel disorders (because of the low fibre content of your diet), iron deficiency (anaemia) and bone disease in later life.
  • Because your stomach will be much smaller after surgery, you will always have to think carefully about the foods you eat.

These changes are likely to affect not only you but also your family and friends, at home and in social situations too, such as family meals and eating out with friends. Your specialist bariatric team will tell you what to expect so that you can prepare your family and friends for the challenges and changes ahead.

* Content on this page is produced with the kind permission of the British Heart Foundation, which is the joint copyright owner with Weight Concern



Obesity surgery - other things to bear in mind

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