Cut the Waist

Cut the Waist

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The philosophy of Cut the Waist is to prevent obesity related ill health through education resources

Weight loss surgery


The surgical treatment of obesity is called bariatric surgery after the Greek word baros meaning "weight" and iatrikos meaning "the art of healing".

Weight loss (bariatric) surgery is an extremely effective way of losing weight and keeping the weight off long term. Bariatric surgery is the only effective treatment for morbid obesity in terms of inducing and maintaining satisfactory weight loss and significantly decreasing weight related co-morbidities.

Bariatric surgery outcome data illustrates that weight loss is the most powerful therapy we have in medicine today. Significant weight loss achieved via bariatric surgery results in a high rate of remission of important obesity-related diseases such as type 2 diabetes, hypertension and obstructive sleep apnoea. It is now well established that bariatric surgery also significantly reduces mortality in those patients eligible for treatment.

Bariatric operations are not simply one-off procedures. Rather they are a lifelong process requiring careful patient selection and programme for long-term follow up and support. As such this form of intervention should only be undertaken by centres offering experienced multidisciplinary pre-operative patient assessment. Crucially, centres should provide evidence of a well established protocol for long term post-operative management as this is so important in ensuring a successful outcome following surgery1.

After Bariatric surgery, most patients lose 50-60% of their excess body weight (%EBW) within three years. This usually equates to a weight loss of 30-40kg (5-6 stones) or more depending upon starting weight. A bariatric procedure would be considered unsuccessful with excess weight loss of less than 25% at two years. In centres of excellence approximately 3% of patients are deemed to have had unsuccessful weight-loss surgical intervention by this criterion. The high rate of success in these centres reflects significant experience in pre-operative counselling and patient selection and excellent long term post-operative support and follow up.

Who is considered eligible for Bariatric surgery?

National Institute of Clinical Excellence (NICE) guidance for bariatric surgery

NICE suggest that surgery should be considered for people who meet the following criteria:

  • BMI 40kg/m2 or more or
  • BMI of between 35kg/m2 and 40kg/m2 and other significant disease (for example type 2 diabetes, high blood pressure) that could be improved if they lost weight
  • commit to the need for long term follow up

Other caveats include

  • appropriate non-surgical measures have failed to achieve or maintain adequate clinically beneficial weight loss for at least 6 months
  • are receiving or will receive intensive specialist management
  • are generally fit for anaesthesia and surgery

Surgery should be considered as a first-line option for adults with a BMI of > 50kg/m2 in whom surgical intervention in considered appropriate; consider orlistat or sibutramine before surgery if the waiting time is long.

An increasing requirement for bariatric surgical procedures

The following graph demonstrates how over that last two decades, there has been an exponential increase in numbers of people who are affected by extreme obesity. Bearing in mind the NICE criteria for eligibility for bariatric surgery, it is easy to see how there is an increasing need for this procedure as a result of the exponential rise in the prevalence of people with BMI of greater than 40, 45 and 50kg/m2 whom stand to gain significant health benefits from this procedure.

Graph: Increasing prevalance of extreme obesity

Extreme obesity poses a serious risk to health

People affected by extreme obesity are at risk of premature death. People with a BMI >35 have twice the risk of death at any age when compared to people who have a BMI within the normal range.

Graph: Body Mass Index versus Mortality

Significant weight loss achieved via bariatric surgery reduces mortality

It is well established that the significant excess weight loss achieved via bariatric surgery in high risk patients improves life expectancy. One series of 1,035 patients with BMI>50kg/m2 who underwent bariatric surgery were followed up for 5years after surgery and death rate of this group was compared to over 5,000 control patients matched for BMI who did not have surgery. The death rate in the surgical intervention group was 89% less than in the group which did not have surgery2.

Graph: Reduction in risk of death after weight loss surgery
Christou et al 2004 Ann Surg; 240(3):416-424

In another study 1,468 patients who underwent a gastric band procedure were followed up for an average of 3.6years to assess mortality in the medium term following the procedure. This surgically treated group were compared to 2119 obese patients who had been followed up over 12years to assess mortality rate. Of the surgically treated group, 5 patients had died compared to 225 who had died in the group of patients that had not lost weight. Following adjustment for length of follow up, sex and weight differences between the two groups to allow direct comparison, the risk of dying had been reduced by 73% in the gastric band-treated cohort3.

Significant weight loss achieved via bariatric surgery facilitates remission of serious obesity-related chronic diseases

In a review of pooled data from 136 studies involving bariatric surgery, participants experienced a mean excess weight loss of 61.2%. A total of 76.8% participants experienced a complete resolution of their type 2 diabetes4.

No other treatment other than significant weight loss can have such a powerful effect on type 2 diabetes. We know that in most cases type 2 diabetes exists as a result of overweight or obesity. Bariatric surgery data demonstrates that in most cases type 2 diabetes disappears with weight loss.

The Swedish Obese Subjects (SOS) study has followed patients over 10years post Bariatric surgery. The SOS data demonstrates impressive long term resolution of significant obesity-related co-morbidities as a result of between 13% and 25% loss of total body weight (note this outcome data appears less impressive as the weight loss is expressed as total body weight loss rather than excess weight loss) achieved via a range of bariatric surgical approaches. It is also important to appreciate that total body weight loss following gastric banding is now in the region of 20% rather than the 13.2% quoted here, as a result of improvements in technique and patient follow-up protocols.

Graph: 10 year weight loss in the SOS study

The SOS study demonstrated the following improvement in health outcomes were achieved as a result of patients undergoing bariatric surgery4.

Medical outcomes of bariatric surgery

Bariatric Surgery and Type 2 Diabetes

Several studies report superior rates of diabetes remission following gastric bypass in relation to those achieved with gastric banding. This may relate to the corresponding differences in short-term weight loss observed. Cottam et al observed Type 2 diabetes remission in 78% and 50% of diabetic RYGB and LAGD patients respectively after a 3-year follow up, however several other studies have found no significant differences in rates of diabetes remission between the two procedures [ see Favaretti paper listed below for a review].

An important study randomised 30 with type 2 diabetes to receive gastric banding and 30 patients to receive conventional medical therapy in order to compare these two different treatment approaches. The patients had BMIs of between 30-40kg/m2 and were within 2 years of diagnosis of type 2 diabetes. The study found marked differences in outcomes in favour of the gastric band at 2years from the start of the treatment. Treatment with the lap-band resulted in 73% remission in type 2 diabetes, associated with a 20.7% loss of total body weight. The conventional medical therapy group achieved a 13% remission rate in type 2 diabetes and a 1.7% loss of body weight. This highly significant result represents a 5.5-fold greater remission rate of type 2 diabetes with surgical gastric band treatment when compared with medical therapy5.

The Lap-band now has a European licence for the treatment of type 2 diabetes via weight loss.

Does surgery actually cure these diseases?

Bariatric surgeons in particular and the wider medical profession in general are understandably extremely impressed with the results of bariatric surgery in terms of significantly improved health outcomes following surgery.

It is however important to exercise a degree of caution when describing a surgical cure for a chronic disease such as type 2 diabetes which may have been present for some years prior to bariatric surgical intervention.

It is important to understand that type 2 diabetes is associated with increased risk of cardiovascular disease, and is the condition is often present for several years prior to diagnosis. Bariatric surgery can result in significant improvements in cholesterol levels and restoration of normal glucose regulation indicating biochemical resolution of T2DM. Bariatric surgery undoubtedly reduces risk and is known to reduce diabetes-related death as a result of remission of this disease postoperatively. However surgery does not reset risk - some excess residual increased risk remains in view of the past history of diabetes. Clinicians may therefore advise continuation of certain some medications e.g. metformin/cholesterol reducing medication after surgery with the idea that the disease is in remission rather implying the disease has disappeared or regarded as "cured" following bariatric surgery. Metformin and statins are known to have "cardioprotective" benefits.

As an example;

Person of 130kg with type 2 diabetes.
Carrying 60kg excess weight.
Loss 50% excess weight after surgery (30kg).
Weight therefore 100kg post operatively.

Surgery results in biochemical resolution of type 2 diabetes in approximately 60% -75% of patients post gastric banding: the so-called "remitted diabetic state".

This person may now exhibit normal glucose regulation without diabetes medication and therefore may be able to discontinue insulin therapy for example. However this person continues to be at increased risk compared with a person of 100kg with no prior history of being 130kg and no prior history of type 2 diabetes.

The person having undergone surgery may therefore benefit from continuing some medication postoperatively e.g. metformin/statin in view of residual excess cardiovascular risk due to prior history of diabetes.

Do people achieve a normal weight after bariatric surgery?

It is important to consider two important concepts regarding health outcomes in relation to Bariatric surgery. People undergoing Bariatric surgery can expect to lose 50-60% of excess weight. This means that after surgery people continue to carry 40-50% excess body weight. Bariatric surgery may not therefore result in people becoming a normal weight, although it can reduce BMI by 10kg/m2. A patient with a pre-operative BMI of 40 kg/m2 prior to surgery may therefore achieve a BMI of 30 kg/m2 following surgery. Although this remains within the obese range, there is a high chance that associated co-morbidities will be resolved by surgery, and as we have seen, bariatric surgery outcome data demonstrates impressive reduction in mortality as a result of this degree of weight loss.

Choice of bariatric procedure

The two most common bariatric procedures are laparoscopic adjustable gastric banding (LAGB) and gastric bypass, also known as Roux en Y gastric bypass (RYGB). Both procedures facilitate weight loss either solely in the case of LAGB or predominantly in the case of gastric bypass, by limiting food intake and enhancing a feeling of fullness (satiety) by effectively reducing stomach size. These bariatric procedures are therefore known as "restrictive" procedures.

In addition to a restrictive component, the gastric bypass also promotes weight loss via introducing an element of malabsorption. As you can see from the following diagram, the gastric bypass involves re-directing or re-routing ingested food away from the main body of the stomach and first part of the small intestine. This effectively reduces contact with digestive enzymes which enter the bowel at this point.

Laparoscopic adjustable gastric band - mechanism of action

Diagram of laparoscopic adjustable gastric banding (LAGB)

Placement of a gastric band just below the gastro-oesophageal junction creates a small pouch of stomach and a degree of restriction which delays the passage of food into the main body of the stomach. The gastric band is a purely restrictive procedure and involves no changing of bowel anatomy to re-route of food and no stomach stapling surgery.

As the signal of feeling full logically comes most strongly from stretching of the top of the stomach when it is full, the restriction at the top of the stomach by the band causes a feeling of fullness very quickly after eating a small amount of food. Once past the band, the food enters the stomach and is digested normally.

Gastric Band (Roux en Y) - mechanism of action

Diagram of gastric bypass (Roux en Y)

The gastric bypass procedure involves surgically fashioning a small pouch of stomach, involving surgical dissection and a stomach stapling procedure. This operation renders to main body of the stomach redundant as it receives no ingested nutrients. The small volume stomach pouch comprises the restrictive component of this procedure.

The small bowel is divided below the duodenum and the distal end of the small bowel is brought up to attach to the newly fashioned stomach pouch. Ingested food receives less digestion as it avoids the stomach and less exposure to stomach acid. It also receives delayed exposure to digestive enzymes from the pancreas which enter the duodenum and only has a chance to mix with ingested food once the food passes beyond the Y- shaped small-bowel anastamosis (anastamosis essentially means the point at which the divided bowel has been re-joined). This comprises the malabsorptive component of the procedure.

The entirely malabsorptive procedures biliopancreatic diversion (BPD) with duodenal switch (DS) are less common procedures and in the main should be regarded as less suitable than the restrictive procedures for the majority of patients considering bariatric surgery in view of the higher operative risk and more significant long term post operative sequele associated with purely malabsortive procedures.

How safe are these restrictive operations?

Both LAGB and RYBG should be regarded as safe procedures with operative mortality approaching zero in experience centres. As gastric bypass involves stomach stapling, dividing and re-joining bowel (anastamosis), the procedure carries more operative risk then the gastric band (LAGB). There is potential for leakage at the points where the bowel has been anastamosed. The published leak rate after gastric bypass ranges from 0.9% to 5.5%.

The operative mortality rate for gastric band (LAGB) is commonly quoted at less as approaching zero (0-0.1%) and for gastric bypass surgery I0.5%6,7

Gastric band (LAGB) requires re-operation in 5-10% of cases, laparoscopically in the vast majority of cases to remedy generally minor occurrences such as slippage of the band, a degree of bowel protrusion above the band (prolapse), or problems with the injection port of tubing. It is important to remember that 90-95% of patients do not require any surgical "maintenance" of this nature. It is also important to note that re-operation in the case of gastric bypass patients is often required for more complex problems such as internal hernia or narrowing of the junctions between the surgically divided and re-joined bowel (anastomotic stenosis) . One study looked at 780 bariatric procedures retrospectively and found that total complications rates were 9% for LABG and 23% for RYGB8.

Safety and implications for patient preference

Patient concern over bariatric operations has been based primarily on safety. In a questionnaire distributed to 470 consecutive patients undergoing bariatric operation in two major centres in two different countries, 85% chose LAGB with 49% claiming "safety" as the reason over gastric bypass and BPD with DS.

Significant pros and cons and long term implications of the procedures

The gastric band (LAGB) is a reversible and adjustable procedure. The gastric bypass should essentially be regarded as an irreversible procedure. It is feasible to reverse a gastric bypass although this is a major operative undertaking.

The gastric bypass is not adjustable. Although impressive weight loss is achieved within the first year of the gastric bypass procedure, the inability to make adjustments to the gastric bypass postoperatively may have implications with regards a reduction in medium to long term efficacy of this procedure and achievement of weight loss maintenance. The adjustability of the gastric band (LAGB) is a significant advantage over gastric bypass.

The change in upper gastrointestinal tract anatomy as a result of gastric bypass brings with it significant benefits such as promoting immediate duodenal rest and facilitating rapid remission of type 2 diabetes. There is also a significant drawbacks of this procedure as it causes a degree of permanent malabsorption of ingested nutrients.

"Duodenal rest" and remission of type 2 diabetes following gastric bypass

Gastric bypass is very effective in producing a dramatic improvement and remission of type 2 diabetes, often within days of surgery. The rapid improvement is possibly related to diversion of ingested nutrients away from the proximal small bowel or duodenum: Gastric bypass is a very effective way of inducing so-called "duodenal rest". It appears that resting the duodenum from contact with nutrients and dietary fat is a significant factor in promoting diabetes resolution. For more information, see the "Duodenal rest" page.

Gastric bypass and malabsorption

Following bypass, ingested food is delivered distally, directly into the ileum. Reduction in fat absorption and therefore fat-soluble vitamin absorption following gastric bypass is a result of reduced contact of ingested food with lipases. These fat-digesting enzymes enter the rested segment of bypassed duodenum via the pancreatic duct and have no contact with ingested food until they reach the anastomosis between the Roux limb with the ileum.

Iron and B12 malabsorption are a consequence of rendering the main body of the stomach obsolete. Dietary iron absorption is ordinarily enhanced by an acidic pH. Acidic conditions are no longer provided when the stomach is bypassed via surgery. Similarly the main body of the stomach ordinarily produces a factor to facilitate B12 absorption (intrinsic factor). As this normal physiology is disrupted with bypass surgery, patients are rendered dependent upon lifelong 3 monthly B12 injections to prevent B12 deficiency and resultant pernicious anaemia after gastric bypass surgery.

Long term weight management post bariatric surgery

Is there a difference in long term effectiveness between LAGB versus RYGB?

An insurmountable challenge for medical weight loss programmes has been the inability to sustained weight loss following these interventions. Bariatric Surgery appears to overcome this challenge with impressive 10-12yr outcome data demonstrating maintenance of sustained weight loss.

Gastric bypass is associated with more dramatic initial weight loss than gastric band (LAGB), particularly within the first year of the procedure when the majority of weight loss after gastric bypass is achieved. Weight loss in the first 1-2years postoperatively predicts success of the procedure, as a degree of weight regain, typically in the region of 5-7kg is normally seen thereafter. Patients should therefore be expected to lose 60-70% excess body weight within the initial 1-2 years post gastric bypass. Failure to do so may result in a less impressive long term weight loss result post gastric bypass, anticipating an inevitable tendency to a degree of weight regain in the medium term following this procedure9.

The significant advantage of adjustability of the gastric band becomes apparent when comparing medium and long term weight loss data associated with gastric band (LAGB). Initial weight loss is slower than with gastric bypass and it takes between 2 to 3years post procedure to achieve 50-60% excess weight loss. However, as the band is adjustable weight regain in the medium term can be avoided with appropriate band adjustment. It is important for clinicians and patients alike to realise that there is not significant difference in terms of excess body weight loss between these procedures after 3years10. The slow, steady rate of weight loss achieved with a gastric band may also have an additional advantage over the more rapid weight loss associated with gastric bypass. Steady weight reduction over 2-3years less likely to result in significant loss of healthy lean tissue mass (muscle). Loss of lean tissue is known to occur as a result of the rapid weight loss post gastric bypass.

Graph: Weight loss: Equally Weight loss: Equally effective at three years and beyond
Gastric bypass (Roux en Y) is not more effective that gastric band (LAGB) in terms of excess body weight reduction at 3years and beyond

The following long term weight loss-maintenance outcome data associated with gastric band (LAGB) demonstrates impressive weight loss maintenance over 10years post procedure. This data underscores the importance of adjustability of the band. If a degree of weight regain is observed at 8-9years post procedure for example, the band can simply be adjusted. The long term data is also a reminder that LAGB requires life-long following up and 6monthly review to ensure appropriate weight loss maintenance continues as a result of ongoing band adjustment where necessary.

Graph: % weight loss Melbourne cohort
Maintenance of weight loss long term reflects the important benefit of adjustability of the gastric band (LAGB) and underscores the importance of long term follow up to achieve long term weight management success following a gastric band procedure


Laparoscopic adjustable gastric band (LAGB) is the safest bariatric operation and might well be the preferred weight loss surgery procedure for the great majority of patients, particularly given recent data suggesting equitable weight loss outcomes between the LAGB and more invasive procedures such as gastric bypass when analysed 3years post operatively.

LAGB has the significant additional benefit of adjustability. Countries such as Australia and USA who have significant experience of a range of bariatric surgical procedures are demonstrating a trend towards less invasive surgical approaches to weight loss such as LAGB. 14,000 bariatric procedures are now performed in Australia each year and over 90% of these are Laparoscopic Adjustable Gastric Banding.

Graph: Australian Medicare item numbers for LAGB and RYGB

The information presented here comparing gastric bypass (Roux en Y) and laparoscopic gastric band (LAGB) procedures may serve to explain the dramatic rise in gastric band procedures in Australia against a background low level of gastric pass surgery over the last 14years.

Recommended reading

The Lap-band solution: A partnership for weight loss
By Paul O'Brien MD
ISBN 978-0-5228-5412-1

The following paper also provides a useful review of the issues relating to these bariatric procedures and highlights the advantages of the gastric band over Roux en Y gastric bypass.

Favaretti F, Ashton D, Busetto L, Segato G, De Luca M. The gastric band: First choice procedure for obesity surgery. World J Surg. Published online 24th June 2009. DOI 10.1007/s00268-009-0091-6 (accessed 7th July 2009)


1. Shen R, Dungay G, Rajaram K et al. Impact of patient follow-up on weight loss after bariatric surgery. Obes Surg; 14: 514-591

2. Christou NV, Sampalis JS, Liberman M et al. Surgery decreases long-term mortality, morbidity, and health care use in morbidly obese patients. Ann Surg 2004; 240: 416-424

3. Cottam DR, Atkinson J, Anderson A et al. A case-controlled matched pair cohort study of laparoscopic roux-en-y gastric bypass and Lap-Band patients in a single US center with three year follow up. Obes Surg 2006; 16: 534-540.

4. Peeters A, O'Brien P, Laurie C et al. Substantial intentional weight loss and mortality in the severely obese. Ann Surg 2007; 246: 1028-1033

5. Dixon JB, O'Brien PE et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA 2008; 299[3]: 316-323

6. Buchwald H, Avodor Y, Braunwald E et al. Bariatric Surgery: a systematic review and meta-analysis. JAMA 2004; 292: 1724-1737

7. Cunneen SA, Phillips E, Fielding G et al. Studies of Swedish adjustable gastric band and Lap-Band: Systemic review and meta-analysis. Surg Obes Relat Dis 2008; 4: 174-185

8. Parikh M, laker S, Weiner M et al. Objective comparison of complications resulting from laparoscopic gastric banding for treatment of morbid obesity. J Am Coll Surg 2006; 202: 253-251

9. Magro DO, Geloneze B, Delfini R et al. Long-term weight regain after Gastric bypass; a 5-year propective study. Obes Surg 2008; 18: 648-651

10. O'Brien PE, McPhail T, Chaston TB et al. Systematic review of medium-term weight loss after bariatric operations. Obes Surg 2006; 16: 1032-1040