Andrew Wardle (left), Mr Haritharan Nageswaran, and Mr David Hewin discuss the viability, benefits, and impact of choosing surgery as a treatment option for obesity

Bariatric surgery in the NHS has increased 785% in 5 years1 and a recent report by the National Bariatric Surgery Registry concluded that surgery is a cost-effective way of improving the health of obese patients.2 Bariatric surgery is significantly better at inducing sustainable weight loss in morbidly obese individuals compared with diet and pharmacotherapy, and can also improve patient co-morbidities.3 However, it has left many physicians questioning its viability and the implications posed for post-operative care. This article discusses:

  • the conditions that should be met before considering bariatric surgery as a treatment option
  • procedure choice and potential complications
  • post-operative management
  • financial impact
  • challenges for commissioning.

Patient eligibility

The National Institute for Health and Care Excellence (NICE) published a countrywide strategy for treating obesity in 2006.4 However, this was only a framework and separate primary care trusts (PCTs) have the autonomy to decide their own individual options and thresholds. NICE recommends offering interventions according to:

  • body mass index (BMI)
  • race (the World Health Organization recommends 2 kg/m2 lower BMI thresholds in Asian patients5)
  • waist circumference
  • obesity related co-morbidities such as type 2 diabetes, hypertension, cardiovascular disease, osteoarthritis, dyslipidaemia, and sleep apnoea.

A summary of the current NICE guidance on treatment strategy is provided in Figure 1.

Treatment choice is a progressive ladder of strategies each trialled as an adjunct to a previous intervention if it fails to provide clinically valuable weight loss after being tried for a minimum of 6 months. The ladder involves:

  1. diet
  2. lifestyle and behaviour
  3. pharmacological treatment
  4. surgery.

Surgery is the final treatment option and requires referral to a specialist obesity management service. However, in patients with a BMI >50 kg/m2, surgery can be considered a first-line option.

As aforementioned, many trusts enforce their own requirements—this has created a postcode lottery. An audit revealed that 28% of PCTs required patients to have a BMI >40 kg/m2 with co-morbidities before accepting referrals for surgery6—thereby exceeding NICE guideline requirements. This rationing has caused patients to seek surgery privately and overseas. However, the long-term healthcare of these patients inevitably becomes the responsibility of the NHS.

Figure 1: Current treatment guidelines as suggested by NICE4


National Institute for Health and Care Excellence. Obesity guidance on the prevention, identification, assessment and management of overweight and obesity in adults and children. Clinical Guideline 43. London: NICE, 2006, updated 2010. Reproduced with kind permission. Available at:

Figure 2: Roux-en-Y gastric bypass nutritional complications16,17
Complication/deficiency Incidence Consequence Investigation results Treatment/prophylaxis
Thiamine (B1) +/- Wernickes encephalopathy, peripheral neuropathy, anaemia ? Thiamine IV: thiamine 500 mg, TDS, 3/7 days; then IV-thiamine 250 mg, OD, 5/7 days; and then PO thiamine 30 mg, bd; multivitamins
Protein +/- Oedema, alopecia ?Albumin; ?pre-albumin 60–90 g daily intake
Iron ++ Anaemia ?Ferritin PO: ferrous sulphate 250 mg, OD, 3/12 days; with vitamin C
Calcium/vitamin D ++ Osteoporosis and osteomalacia ?Parathyroid hormone
?25-(OH)D; ?DEXA
Bisphosphonates, calcitriol; calcium citrate (1.2–2 g/day); vitamin D (10–20 µg/day)
Vitamin B12 ++ Neuropathy, anaemia ?Vitamin B12 ?Homocysteine Vitamin B12 1 or 2 mg, OD; IM: hydroxocobalamin 3 mg, every 6 months
Folic acid +/- Foetal neural tube defects, anaemia ?Folate; ?homocysteine Oral: folate 1–5 mg, OD; multivitamins
Sugar intolerance ++ Dumping syndrome: bloating <30 minutes post-prandial N/A Octreotide: 20 mg IM; carbohydrate avoidance
+ Endogenous hyperinsulinemic hypoglycaemia: palpitations, dizziness, <3 hours post-prandial N/A Acarbose, octreotide: 20 mg IM; carbohydrate avoidance
Oxalosis + Kidney stones, nephrolithiasis, acute renal failure N/A N/A
Copper +/- Anaemia, neutropenia, leukopenia ?Copper IV copper; healthy diet
Cholelithiasis + Especially with rapid weight loss Ultrasound Ursodeoxycholic acid
Vitamin A +/- Night blindness ?Vitamin A Multivitamins
Vitamin K +/- Coagulopathies ?INR; ?Vitamin K1 Multivitamins
Vitamin E +/- Rash ?Vitamin E Multivitamins
Zinc/selenium ++ Alopecia, acrodermatitis ?RBC-zinc; ?selenium Multivitamins
Vomiting ++ Hypokalaemia, dehydration ?Electrolytes; ?haematocrit Rehydration salts; parenteral nutrition
Vomiting >6/12 months + Obstruction, reflux Endoscopy, contrast study Hospital referral

IV=intravenous; TDS=three times daily; OD=once daily; PO=oral medication taken by mouth; DEXA=dual energy X-ray absorptiometry; IM=intramuscular injection; INR=international normalised ratio; RBC=red blood count
++ very frequent; + frequent; +/-rare

Patient suitability

In addition to fulfilling PCT requirements, the patient’s state of health and physiological maturity is also crucial in determining if bariatric surgery is an appropriate option. Many surgeons feel uncomfortable operating on patients aged under 18 or over 65 years. Coupled with this, a patient should also be:4

  • fit for surgery and anaesthesia
  • committed to long-term follow up and dietary and lifestyle changes
  • accurately informed about procedure risks and predicted benefits
  • able to access psychological support before and after surgery
  • free of major psychiatric or behavioural disorders.

Patient assessment should include their motivation for undergoing surgery (most common reasons include health grounds [52%] and social stigma [32%]).7 Patient motivation is paramount to avoiding the not uncommon psychiatric complications (e.g. disappointment at results of surgery). Patients also need realistic weight-loss goals and should be cautioned that surgery does not guarantee weight loss. Bariatrics is based on the idea of excess weight, the difference between a patient’s current weight, and what their weight would be if they had a BMI of 25 kg/m2. The results of surgery are reported as percentage excess weight-loss (EWL) calculated using the following formula = (weight loss since pre-operative measurement x 100) / (starting weight – ideal weight).


If NHS bariatric surgery is to be pursued, the GP must first send letters of referral via the local weight-management service. These should include current details of the patient’s:

  • height, weight, and BMI
  • date, duration, and weight lost with previous anti-obesity strategies
  • blood pressure, lipid, diabetes, and endocrine screens
  • complete past medical history
  • smoking, alcohol, and recreational drug history
  • endocrinological reasons for obesity
  • readiness for change, body image, motivation, and compliance history.

The hospital team will outline the risks and long-term implications of surgery to the patient, but these will inevitably impact on management in primary care. Surgical risks include bleeding, thrombosis, and infection, as well as procedure-specific complications; GPs should ensure that their patient fully understands these risks. The 18-week patient pathway for GP referral to hospital treatment applies to bariatric surgery; however, consultants and patients often agree on observation periods that precede the decision for surgery, therefore resulting in a delay to the start of the 18 weeks.

Pre-operative diet

Fat and carbohydrate restriction (for a variable time period depending on the surgical team’s practice) is advised prior to surgery. This limits operative complications by reducing liver glycogen and therefore size.8,9

Procedure choice

Surgery preference should be chosen through an informed decision by the patient based upon three core principles:4

  • patient—BMI and co-morbidities
  • current evidence—procedure efficacy and complications
  • surgeon—facilities, equipment, and experience.

The NHS offers multiple forms of surgery including:

  • bilopancreatic diversion
  • intra-gastric balloon
  • laproscopic roux-en Y gastric-bypass (RYGB)
  • laproscopic gastric band (LAGB)
  • sleeve gastrectomy.

Currently RYGB and LAGB are the most common procedures in the UK and are discussed below.

Roux-en-Y gastric-bypass

An RYGB is a combined restrictive-malabsorptive procedure that creates a proximal stomach pouch directly connected to the jejunum, therefore bypassing parts of the stomach, duodenum, and proximal jejunum, which are subsequently joined into the new descending jejunum. This limits food intake before satiety and therefore reduces the volume available to be absorbed. An EWL of 60%–70% can be expected.2

Acute complications
Post-operative hospital stays are typically 3–5 days with a 9.7% chance of readmission within 28 days.10 Acute complications include infection (4.4%), haemorrhage (2.3%), and strictures (1.6%).11 These are generally treated in hospital, but GP vigilance for associated signs is essential. The 30-day mortality rate of RYGB is 0.5%.10

Long-term complications
Mechanical complications are rare12–15 (see Table 1), however nutritional sequelae, such as thiamine and calcium deficiency are considerable and outlined in Figure 2 . The latter can represent a significant burden of care. Primary care can help avoid this by following prophylactic techniques as suggested in Figure 2. There are no national guidelines on follow-up assessment, but a consensus among physicians is emerging (see Table 2).16,17 To help reduce problems, a GP can:

  • prescribe sugar-free medications (prevents dumping syndrome)
  • advise on multivitamin supplementation, especially for patients on diuretics (electrolyte and thiamine disturbance)
  • prescribe non-gastric irritants and prophylactic proton-pump inhibitors and advise the patient to avoid gastric irritants (increased ulcer vulnerability)
  • provide advice on timing supplementation to maximise absorption.

The RYGB procedure can increase cholelithiasis risk particularly during rapid weight loss.2

Table 1: Mechanical complications associated with bariatric surgery13-15 
  Differential diagnosis Symptoms Incidence (%) Acute management  
LABG Band leakage Poor weight loss 7–8 Refer for surgery Hospital referral
Over-tight or migrating band Epigastric pain, vomiting, and food intolerance 6–7 Proton pump inhibitors
Band erosion Pain, recurrent infection, and bleeding <4 Antibiotics and proton pump inhibitors
Band slippage Dysphagia, vomiting 1–3 Band deflation
RYBG Anastamotic stricture Dysphagia, nausea, bowel obstruction 3–11 Refer for endoscopic dilation—avoid NSAIDs and stop smoking
Anastomotic leak Pain, infection 1–6 Analgesia, antibiotics, and rehydration
Internal hernia Pain, vomiting 1 Refer for surgical intervention—pain relieved by going on all fours
LAGB=laproscopic gastric band; RYGB=roux-en Y gastric-bypass; NSAID=non-steroidal anti-inflammatory drug
Table 2: Screening guide for RYGB and LAGB 16,17


Laproscopic gastric-band

Gastric band surgery is a reversible and restrictive procedure using an adjustable saline-filled stomach band to control stomach volume and induce early satiety. An EWL of 40%–60% can be expected (pers.comm).

Acute complications
Hospital stays last an average of 2–3 days and readmission rates are 6.4%.10 Acute difficulties include infection (1.3%) and respiratory impairment (0.35%)11—these are usually resolved in hospital. The 30-day mortality rate of LAGB is 0.1.10

Long-term complications
Mechanical complications are more frequent with LAGB than RYGB (see Table 1),1 and include band leakage and migration. Furthermore, a variable amount of band re-adjustment, via a subcutaneous port, is required; this takes place during a hospital outpatient appointment, the first of which is generally 6–8 weeks post-surgery. Like the RYGB, the LAGB procedure can increase cholelithiasis risk particularly during rapid weight loss.2 Nutritional deficiencies are less common, but can occur with poor diet, protein intolerance, and vomiting; the latter is commonly related to poor band adjustment. Multivitamins are nevertheless advised and calcium and vitamin D status may require supplementation.

Post-operative diet

The surgical team prescribes the immediate diet following the operation, but patients should stop eating when full (usually within 20 mouthfuls) and restrict meal-time fluids in order to avoid straining their new stomach. Instead, 1–2 litres per day of calorie and fizz-free fluids are advised between meals. Typical diets include:

  • Week 1: fluid-based; avoiding sugars although sweeteners are allowed Weeks 2–4: four to five pureed 100 g meals daily. Generally meals that are high in fibre, protein, sugar, or fat are poorly tolerated
  • Weeks 4–6: food as described above but now mashed consistency.

Once the patient is ready to consume solids, a long-term daily diet of three appetising, sustainable, and low-fat and low-sugar meals containing 60–90 g of protein and dairy, five fruit and vegetable portions, and two carbohydrate portions is suggested.2

Long-term weight loss
Results at 18 months post-surgery can be dramatically different to those at 5 years, and patients generally undergo phases of weight change with initial loss peaking at 18 months, followed by a period of stabilisation. However inadequate concordance can cause subsequent weight regain.

General practitioners should be careful to observe progress and look for any of maladaptive behaviours. Disappointing weight loss or weight regain should be assessed. Common reasons include:

  • maladaptive eating:
    • calorie-dense foods
    • >5 meals daily
    • food grazing
    • high-calorie drinks
    • satiety adaptation
  • decreased metabolism:
    • age
    • limited activity
  • deterioration of gastric pouch integrity:
    • liquids with meals
    • carbonated drinks
  • band leak
  • gastro-gastric fistula (RYBG)
  • poor band adjustment (LAGB)
  • psychological complications.

Metabolic changes

Mortality risk is increased by obesity but surgery reduces this by 30.7%.18 Surgery can also improve and resolve type 2 diabetes2 and sleep apnoea2 (see Table 3), and infertility19 and gastric reflux.20 Bariatric surgery has been shown to be effective in the remission of type 2 diabetes.21 An audit has shown that 85.5% of individuals with type 2 diabetes prior to surgery showed no indication of the disease at 2-year follow up.2

Metabolic changes following surgery may mean alterations in medication are required. However, any adjustments must be carefully monitored to ensure resolution of co-morbidities are long-term. Physicians should also be aware of misleading risk factor resolution when there could already be substantial subclinical pathology
(e.g. substantial atheromatous plaques, the growth of which was accelerated by the diabetes, will still remain and threaten to cause angina or peripheral arterial disease).

Table 3: Co-morbidity associated with bariatric surgery2 
Co-morbidity Incidence (%)
Pre-operative 12 months post-surgery
Type 2 diabetes 26.8 13.2
Hypertension 31.6 20.4
Dyslipidemia 16.8 8.2
Sleep apnoea 14.6 6.1

Psychological effects

Low self-esteem, discrimination, and psychopathology are increased by obesity while bariatric surgery promotes happiness, relief from depression,2 and economic activity.7 However, rates of divorce22 and suicide23 are higher and therefore post-surgical patients require careful monitoring. Patients may also desire cosmetic surgery after developing excess skin flaps—this is not always funded by the NHS.

Financial implications

It has been estimated that if only 25% of eligible patients underwent bariatric surgery, £1.3 billion could be saved over 3 years.24 Procedure costs are not covered by ‘payment by results’ and therefore subject to local tariffs; typical fees can cost up to £7000 and £14,000 for LAGB and RYGB, respectively.25 Together with tariffs for consultant outpatient appointments of £200 for an initial appointment and £100 for subsequent follow ups, bariatric surgery represents significant investment. However, if set against 1 year’s worth of weight reduction prescriptions at £400 and the possible average saving of £3000 per year resulting from remission of type 2 diabetes, these costs could be recouped within 3 years.2

Commissioning challenges

Evidence of the financial viability of bariatric surgery is rising and increasing pressure is being placed upon PCTs to commission more operations and open further bariatric centres. However, the high costs mean many trusts simply cannot afford to meet demand, especially under their current financial restraints. In addition to funding and support of the surgical procedure, there also needs to be provision for peri-operative specialist services, such as bariatric endocrine clinics and dietician services. Currently one-third of primary care organisations (PCO) refer patients who need such services to other PCOs.25

Interestingly, with the possibility of GP consortia replacing PCTs, there may be a marked increase in the number of operations being carried out as greater emphasis is placed on evidence-based practice. However the existing financial limitations will need to be overcome if long-term benefit is to be accrued.


Bariatric surgery in the UK is rapidly expanding and already benefiting many patients. However, undergoing the procedure is a serious decision. The potential complications and lifelong changes in lifestyle mean discussing realistic long-term outcomes with the patient, and keeping abreast of developments in post-operative care is essential.


Special thanks to nurse, Sue Bridgewater, and general practitioner, Dr Susan Whittles.

  • Bariatric surgery is effective, but represents a significant cost burden to commissioning budgets
  • Although it might be cost-effective long term, the QIPP challenge means that there may have to be limits on investment in bariatric surgery to meet budget restrictions
  • Local obesity management specialists, commissioners, and surgeons should define local pathways for the referral and management of patients to weight management services
  • These pathways:
    • should identify individuals who are most likely to benefit from bariatric surgery
    • could be included in the QOF indicators for quality and productivity on elective referral (QP6, QP7, QP8)
  • Commissioners should agree local budgets for bariatric surgery that include locally negotiated prices for interventions as these lie outside the payment-by-results tariff
  • This could include a competitive process to identify cost-effective providers if there is more than one suitable provider available
  • Some of the necessary follow up could be commissioned as a locally enhanced service from primary care or via a community specialist bariatric nurse to avoid more expensive outpatient costs.
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