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Weight loss surgery, also called bariatric surgery, is used as a last resort to treat people who are dangerously obese (carrying an abnormally excessive amount of body fat).
This type of surgery is only available on the NHS to treat people with potentially life-threatening obesity that will not respond to non-surgical treatments, such as lifestyle changes.
Potentially life-threatening obesity is defined as:
See below for information on how to calculate your BMI.
For people who meet the above criteria, weight loss surgery has proved to be effective in significantly and quickly reducing the amount of excess body fat (see Weight loss surgery - how does it work).
However, the first treatment to consider for anyone who is obese is losing weight. This can be achieved through a healthy, calorie-controlled diet and increased exercise. It is always recommended that you try to lose weight this way before you consider weight loss surgery, as surgery carries a risk of complications and requires a significant change in lifestyle afterwards.
Because of the risks associated with weight loss surgery, most surgeons, whether they are working privately or for the NHS, would only consider a person for surgery if there was a clinical need, and not just for cosmetic reasons.
For more information, see Weight loss surgery - who can use it.
Availability of weight loss surgery
Even if you are eligible for weight loss surgery, the demand for this surgery on the NHS is currently higher than the supply in many areas of the country. Therefore, there may be a considerable waiting list.
In total, 4,211 weight loss procedures were carried out on the NHS in April 2008 to April 2009.
Weight loss surgery is also available privately. Prices are around:
An increasing number of people are seeking treatment abroad as costs for private treatment are often cheaper in other countries, but this option should be considered carefully. For more information, see Planned treatment abroad.
Types of weight loss surgery
The two most widely used types of weight loss surgery are:
Several other surgical techniques may be recommended in certain circumstances.
For more information, see Weight loss surgery - how it is performed.
Life after weight loss surgery
Weight loss surgery can achieve often impressive results in the amount of weight lost, but it should not be seen as a magic cure for obesity.
People who have had weight loss surgery will need to stick to a rigorous and lifelong plan afterwards to avoid putting weight back on or long-term complications.
This plan will include:
The rapid weight loss that can occur after weight loss surgery may cause relationship problems, for example with a partner who is also obese, and it may result in unwanted loose folds of skin, which may require further surgery to correct.
Also, many people with mental health problems, such as depression or anxiety, find that these problems do not automatically improve because they have lost weight.
It is important to have realistic expectations about what life after weight loss surgery will be like.
As with all types of surgery, weight loss surgery carries the risk of complications, some of which are serious and potentially fatal, such as:
It is estimated that the risk of dying shortly after bariatric surgery is around 1 in 200.
However, this risk can be as high as 1 in 40 if you have other risk factors such as high blood pressure or a BMI of 50 or above.
For more information, see Weight loss surgery - risks.
As long as a person is willing and able to stick to their agreed plan afterwards, surgery can effectively reduce their weight and treat conditions associated with obesity, such as diabetes.
Recent research carried out in America found that on average:
Both techniques also lead to a considerable improvement (and sometimes a complete cure) of obesity-related conditions, such as diabetes or high blood pressure.
Body mass index and obesity
The most widely used way to measure your size is to calculate your body mass index (BMI). This is your weight in kilograms divided by your height in metres squared:
BMI does not provide an accurate assessment of weight in all circumstances, such as in people who are very muscular or children going through a sudden growth spurt.^^ Back to top
Weight loss surgery is used to treat morbid obesity that has failed to respond to non-surgical treatments. Morbid obesity is defined as having a body mass index (BMI) of 40 or above.
It is also used to treat severe (but not morbid) obesity that is associated with a potentially life-threatening condition, such as heart disease, and that has not responded to non-surgical treatments. Severe obesity means having a BMI of 35-39.
Why it is used to treat morbid obesity
Morbid obesity is a very serious health condition that can affect almost every biological system in the human body. It is thought that morbid obesity increases your risk of many different health conditions, such as diabetes and getting blood clots. These conditions are outlined below.
The cardiovascular system is made up of the heart and blood vessels. It is involved in circulating oxygen-rich blood around the body.
People with morbid obesity are vulnerable to the following cardiovascular conditions:
Health conditions that affect the cardiovascular system are collectively known as cardiovascular disease.
Respiratory conditions often seen in people with morbid obesity include:
Metabolism is the term for all the chemical reactions used by the body to break down food into energy.
Metabolic conditions often seen in people with morbid obesity include:
Muscle, joint and bone conditions
The excessive weight associated with morbid obesity places extra pressure on the bones, muscles and joints. This can result in conditions such as:
Eating a high-fat diet, especially for many years, can disrupt the normal workings of the digestive system as it is unable to digest excessive amounts of fats and carbohydrates.
Digestive conditions associated with morbid obesity include:
Morbid obesity significant increases the risk of getting some types of cancer, such as:
Mental health conditions
People who are morbidly obese often have a poor quality of life and low self-esteem. This makes them potentially more vulnerable to developing mental health conditions such as:
Why it is used to treat severe obesity
Weight loss surgery may also be recommended to treat severely obese people (with a BMI of 35-39) who:
Examples of these types of conditions include:
Obesity and life expectancy
Because of the health conditions outlined in this section, the life expectancy of somebody with untreated obesity can be up to 20 years shorter than a person of normal weight.^^ Back to top
The National Institute for Health and Clinical Excellence (NICE) recommends that weight loss surgery should only be offered on the NHS if all the following conditions apply:
There may be slightly different criteria at your local Health Board which could affect your access to surgery.
If you pay for private surgery, it is still likely that a surgeon will only agree to perform surgery if similar criteria are met, due to the risks associated with surgery.
Contraindications to weight loss surgery
A contraindication is a medical term that refers to reasons why a person should not receive a particular treatment. This is because it would not be safe or appropriate for them.
There are two main contraindications to weight loss surgery.
The first is if you have a serious illness that would not be improved with weight loss surgery, such as:
The second is if you have a mental health condition or other underlying factor that makes it unlikely that you would commit to long-term follow-up and the required lifestyle changes.
Examples of these conditions and factors include:
Weight loss surgery would only be considered to treat children who are obese in exceptional circumstances, and only if the child is physically mature (this would be around the age of 13 for girls and 15 for boys).
Most experts in obesity would only recommend surgery as a treatment of last resort for children who are severely morbidly obese (a BMI of 50 of above), or who are morbidly obese (a BMI of 40 or above) and also have a serious health condition that would improve if they lost weight.^^ Back to top
How weight loss surgery works
To understand how weight loss surgery works, it is useful to know how the human digestive system functions.
The digestive system
The digestive system has three main sections:
The food you eat passes down into your stomach. The stomach releases liquids, known as gastric juices, that help break down the food into a more liquid form.
The muscle that surrounds the stomach causes the stomach to contract. The partly digested food is broken down into smaller and smaller pieces which can pass through the small intestine without any problem.
The stomach is the part of the digestive system that appears to cause feelings of hunger. It is thought that once the amount of food inside the stomach falls below a certain level, nerve endings inside the stomach transmit signals to part of the brain known as the hypothalamus, which then triggers feelings of hunger.
For reasons that are still unclear, the ‘hunger threshold’ often appears to be much lower in obese people, so they regularly fill their stomach with food to avoid being hungry.
The small intestine
The small intestine is an extremely long tube (up to 7 metres in adults) that coils around itself at the bottom of your abdomen.
The small intestine digests the various nutrients from food that your body needs, such as:
The large intestine
The large intestine is essentially the exit point of the digestive system. Its role is to transport any waste materials left behind in food out of your rectum and anus (back passage) when you pass stools.
Methods used in weight loss surgery
The various types of weight loss surgery use two main methods to achieve weight loss:
Some types of weight loss surgery, such as a gastric bypass, use a combination of both methods to achieve weight loss.^^ Back to top
Weight loss surgery and adapting to life after surgery is a challenging process, requiring the input of not just the surgeon but many different medical professionals working together as a team. This is known as a multidisciplinary team (MDT) and it may consist of:
Most MDTs operate out of specialist bariatric surgery units, which are typically based in larger hospitals.
Before your weight loss surgery can take place, you will probably be referred to your nearest specialist unit so an assessment can be made to see if you are a suitable candidate for surgery.
Your assessment may consist of three main phases:
The purpose of the physical assessment is to check whether you have any health problems or there are other factors that could complicate your surgery.
As part of your physical assessment, you may receive the following tests:
The psychological assessment determines whether:
The process of assessment can differ from unit to unit, but it is likely you will be asked questions about:
Having a mental health condition such as depression, or an eating disorder such as binge eating, does not automatically mean you are not suitable for surgery. These types of conditions and disorders are very common among obese people.
However, surgery may be delayed until the particular condition or disorder is under control.
The nutritional assessment has two main purposes.
The first is for the dietitian to obtain a detailed history of your current diet and associated patterns of eating and how these have contributed to your obesity.
The second is to ensure that you fully understand the dietary commitments you will need to make after surgery, which may include:
Your dietitian may also recommend that you go on a calorie-controlled diet for several weeks or months before surgery. This is because losing even a modest amount of weight before surgery is known to reduce the risks of complications, especially if you are going to have keyhole surgery.^^ Back to top
The two most widely used types of weight loss surgery are:
Each type of surgery is discussed in more detail below.
Gastric banding is usually performed as a type of laparoscopic (keyhole) surgery, where a series of small incisions is made in the abdomen, rather than one large incision. The advantage of this type of surgery is that 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 performed using a general anaesthetic, which means you will be asleep during surgery and will not feel any pain.
The surgeon will make the incisions in your abdomen and then insert an instrument known as a laparoscope through one of the incisions. A laparoscope is a small flexible tube that contains 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 incisions 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 and the size of the pouch to be adjusted as required after surgery.
The surgery usually takes around an hour to complete.
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.
The weight loss after a gastric bypass is usually more impressive 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 do not like 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.
A sleeve gastrectomy is a type of surgery that can be 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. This should reduce excess body weight by 20%.
Once this weight loss has been achieved, it should be possible to perform either a gastric band or bypass safely.
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 flatulence (passing wind) and 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.
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).^^ Back to top
Recovering from a gastric band operation
When you wake after surgery, you will probably have some pain at the site of the surgery. This is normal and should pass within a few days.
Blood clots are an uncommon but serious complication that can occur after banding, including:
To reduce the risk of blood clots, you may be given a blood-thinning medication, such as heparin, and compression stockings to wear.
Once you feel well enough, move around as much you can as this will further reduce your risk of blood clots.
For the first 24 hours, you will only be allowed to drink a small amount of liquids. This is because your stomach will be very swollen and sore from the effects of the surgery.
Gradually, small amounts of solid food will be introduced into your diet. For more information, see Weight loss surgery - recommendations.
Most people are well enough to leave hospital within 48 hours after surgery and can resume normal activities within four to six weeks.
Four to six weeks after surgery, your stomach should have healed enough that your band can be adjusted by inflating it with saline (sterile salt water).
This is done by numbing your abdomen with a local anaesthetic, using an X-ray to locate the band, then placing a needle into the access point through which the saline is pumped. The band will then inflate, which will constrict the upper pouch of your stomach. The whole process takes around 15 minutes.
Often, this process of adjustment is a fine balancing act. If the upper pouch is too large, you may not lose much weight. If the upper pouch is too small, you may vomit after eating.
Therefore, it can take a number of sessions before the ideal adjustment for your band is reached.
Recovering from a gastric bypass
Once you wake after surgery, you will probably have a drip in your arm, to provide your body with liquids, and a tube in your bladder, known as a urinary catheter, to drain urine out of your bladder.
These tubes will be removed once you are well enough to get out of bed.
Again, you may be given blood-thinning medication and compression stockings to wear to help prevent blood clots.
You will only be allowed a liquid diet immediately after surgery, and solids will be slowly introduced into your diet.
Most people are well enough to leave hospital three to six days after surgery and resume normal activities within three to five weeks.
Recovering from other types of weight loss surgery
The recovery time for other less commonly used types of weight loss surgery are:
The advice about adopting a liquid diet immediately after surgery and then gradually introducing small amount of solids also applies here.^^ Back to top
Diet after weight loss surgery
Diet plans can differ between specialist centres and depending on your individual circumstances, but most people will be given a plan similar to the ones described below.
Diet after a gastric band operation
Your diet after a gastric band operation will progress over three main stages:
Each stage is discussed in more detail below.
First four weeks
It is very important that any food you eat during this period is pureed. Attempting to eat solid foods at this stage could put pressure on the band and damage it.
Pureed food has the same texture and consistency of baby food. You can puree food using a food processor, hand-held blender or potato masher.
Additional fluids, such as sauces or water, may be required to soften some types of food.
Aim to eat small portions four to five times a day. A portion is around 100g or 5-6 tablespoons of food. Eat all your meals slowly, taking small mouthfuls.
Stop eating as soon as you feel full. Because of the position of the band, you will probably experience a feeling of fullness or tightness in your chest rather than in your stomach.
Drink around 1.5 litres (2.5 pints) of water a day. Drink small glasses, around 100-200ml, between meals but never with your meals.
If you experience repeated episodes of vomiting after eating, it may be a sign that you are eating too much or that your band needs to be adjusted. Contact your surgical unit for advice.
Weeks four to six
Continue to eat a similar diet as you did for the first four weeks, but your food no longer has to be pureed, although it should be soft.
For example, you could eat:
After six weeks
After six weeks, you will be ready to adopt a long-term diet that you will need to stick to for the rest of your life. Your band should now be adjusted correctly so you should need to eat much less to satisfy your appetite.
While weight loss is an important goal of your diet, do not neglect the nutritional content of your diet. See below, for more information on what makes a healthy, nutritional diet.
The British Obesity Surgery Patient Association (BOSPA), a charity for people who could benefit from surgery, recommends that to get the most benefit from your gastric band, you need to follow six golden rules:
Diet after a gastric bypass
The progression of diet stages after a gastric bypass is broadly similar to those after a gastric band:
The golden rules above also apply to your diet after a gastric bypass.
However, you need to be aware of several additional issues.
Firstly, you will need to avoid eating food that is high in sugar, such as chocolate, cakes, sweets and biscuits. This is because your bypass will affect how you digest sugar, and any sugar you eat will trigger your body to produce high levels of insulin.
The excessive amount of insulin can cause a number of unpleasant symptoms that are collectively known as dumping syndrome. Symptoms of dumping syndrome include:
Secondly, you will need to take daily vitamin and mineral supplements, as your small intestine will no longer be able to digest all the vitamins and minerals your body needs from your diet.
The dosage and type of supplements can vary from case to case, but most people are required to take:
Diet after other types of weight loss surgery
The recommended diet after other types of weight loss surgery is likely to be similar to the advice above.
Your specialist centre will be able to provide more detailed advice.
Exercise after weight loss surgery
Losing weight and then maintaining a healthy weight does not simply involve reducing the amount of calories you eat. Burning calories while exercising is also important.
Regular exercise also has additional health benefits other than weight loss. These include reducing your risk of developing heart disease and some types of cancer, and boosting your self-esteem and wellbeing.
You will probably be given an exercise plan that starts gradually with low to moderate amounts of physical exercise, such as 10 minutes a day, before the amount is gradually increased.
Most people will be set a goal of exercising for at least 30 minutes a day, every day of the week.
The exercise should be intense enough to leave you feeling out of breath and getting your heart beating faster.
Recommended types of physical exercise include:
Chose physical activities that you enjoy as you will be more likely to continue doing them.
A healthy balanced diet
What you eat is just as important as how much you eat to achieve a healthy diet and lifestyle after your surgery.
Your exact recommendations will depend on your individual circumstances and the type of surgery that you have had. However, generally, the advice is similar to the advice given to the general public.
Your diet should contain a healthy mix of the five main food groups:
Your specialist centre can give you more advice on how best to meet your individual nutritional needs.^^ Back to top
As long as you stick to the recommendations on diet and exercise, all types of weight loss surgery can achieve good and often impressive results.
However, rapid weight loss can cause complications. See Weight loss surgery - risks for more information.
A person with a gastric band should expect to lose 50% of their excess body weight within two years.
The weight loss is a gradual process with:
Also expect to see a marked improvement in health conditions related to obesity, particularly:
Most people also report an improvement in their overall quality of life in terms of:
A person with a gastric bypass should expect to lose 70% of their excess body weight within two years.
The weight loss tends to be more rapid in the first year (60% of the excess weight lost) then slows in the second year, with only an additional 10% weight loss.
Again, expect to see a marked improvement in the health conditions above.^^ Back to top
The rapid weight loss associated with weight loss surgery can cause a number of side effects and has a number of risks. These are outlined below.
Complications immediately after surgery
Complications that can occur during or immediately after surgery include:
While weight loss surgery can successfully remove the fat in the body, it cannot cause skin to revert to its pre-obesity tightness and firmness.
Therefore, if you were obese, especially for many years, you may be left with excess folds and rolls of skin, particularly around the breasts, tummy, hips and limbs.
These folds and rolls normally become most apparent 12-18 months after surgery. They can look ugly and are difficult to keep clean, so you may be vulnerable to developing rashes and infections.
Cosmetic surgery can be used to remove the excess skin. However, as this treatment is for cosmetic and not clinical reasons, it is not available on the NHS.
The price for a course of skin-removal treatment can range from £1,500 to £6,000 depending on the amount of skin that needs to be removed.
For more information, see the topic on Cosmetic surgery.
Around 1 in 12 people will develop gallstones after weight loss surgery, typically 10 months after surgery.
Gallstones are small stones, usually made of cholesterol, that form in the gallbladder.
In most cases, gallstones do not cause any symptoms. However, if they become trapped in a duct (an opening or channel), they can irritate and inflame the gallbladder and cause symptoms, such as:
For more information, see the topic on Gallstones.
Psychosocial effects of surgery
While most people who undergo weight loss surgery report an improvement in their quality of life, several psychosocial effects may be related to rapid weight loss.
The word psychosocial describes a person’s psychological development and how they relate to other people socially.
Some people have reported relationship problems with their partner as their partner begins to feel nervous, anxious or possibly jealous about their weight loss.
Additionally, social occasions that revolve around food, such as family meals, can become awkward, as it is common to feel self-conscious about your reduced capacity to eat.
It is also reasonably common for a person to experience a worsening of mood when their weight stabilises, typically two years after surgery. This is often because many people realise that many of their problems that existed before surgery, such as money worries or problems with work, are still there after surgery. You may find it useful to discuss these issues with people who have also had weight loss surgery.
A common complication in people with a gastric bypass is that the hole (stoma) that connects their stomach pouch to their small intestine becomes blocked by a piece of food. This is known as stomal stenosis and is thought to occur in one-fifth of people with a gastric bypass.
The most common symptom of stomal stenosis is persistent vomiting.
Stomal stenosis can be treated by directing a small flexible tube, known as an endoscope, to the site of the stoma. A balloon attached to the endoscope is inflated to unblock the stoma.
The best way to prevent stomal stenosis is to always cut food into small chunks, chew the chunks thoroughly and avoid drinking during meals. For more information, see Weight loss surgery - recommendations.
Gastric band slippage
Gastric band slippage is a complication that affects around 1 in 50 people with a gastric band.
As the name suggests, the band slips out of position. This means that the stomach pouch becomes bigger than it should be. This can cause symptoms such as:
Further surgery will be required to repair the band.
Around 1 in 35 people with a gastric band develop a food intolerance, often many years after their surgery.
A food intolerance is when your body is unable to tolerate certain foods, such as red meat or green salad, resulting in a number of unpleasant symptoms such as:
The reason why a food intolerance can develop after surgery is unclear.
In most cases, avoiding foods that trigger a reaction should help improve symptoms, but if you have persistent symptoms associated with a number of different foods, it may be necessary to remove the band and replace it with a gastric bypass.
No surgery is entirely safe and all surgical procedures carry a risk of death, however small.
Death can occur for a number of reasons during or shortly after weight loss surgery, including:
The risk of dying is:
A number of risk factors have been identified that increase the risk of death during or shortly after weight loss surgery. These are:
Known risk factors for a pulmonary embolism include:
The risk factors above can have a significant impact on your individual risk of death. For example, if you had no risk factors, your risk of death would 1 in 500. If you had four or more risk factors, your risk of death could be as high as 1 in 40.
However, untreated obesity, especially morbid obesity, carries a significant risk of premature death itself.
In most cases, the benefits of surgery outweigh the risks in people who meet the National Institute for Health and Clinical Excellence's criteria for weight loss surgery. For more information, see Weight loss surgery - who can use it?^^ Back to top
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