Bariatric Surgery vs. weight management

Surgery remains the most effective and cost-effective long-term approach to reducing weight for adults adults with severe obesity, according to research from the University of Aberdeen, Aberdeen, UK Health Forum, London and the University of Oxford, Oxford, UK. However, the study also found that high quality weight management programmes (WMPs) are effective tools in reducing weight for up to 10 years in some cases.

"The purpose of this study was to examine the available evidence looking at the effectiveness and cost-effectiveness of different weight management procedures from the perspective of the NHS,” said lead author, Professor Alison Avenell from the University of Aberdeen. "Whilst the study shows that surgical interventions remain much more effective, provision of surgery for obesity management by the NHS is presently very low. Other weight management programmes can be effective in terms of helping people who are severely obese lose weight and are cost-effective for the NHS."

The outcomes of the REBALANCE study, were published in the paper, ‘Bariatric surgery, lifestyle interventions and orlistat for severe obesity: the REBALANCE mixed-methods systematic review and economic evaluation’, which was funded by the National Institute for Health Research (NIHR). In the study, the researchers reviewed 236 studies looking at evidence for acceptability, effectiveness and value for money of surgery, diet and exercise weight management programmes, and the drug orlistat.

They undertook four systematic reviews, which were of:

  • Randomised controlled trials (RCTs) or quasi-randomised trials of bariatric surgery, lifestyle WMPs and orlistat (approved by the National Institute for Health and Care Excellence) with mean or median follow-up durations of ≥ 12 months. We included comparisons between interventions or comparisons with usual care/controls.
  • UK lifestyle WMPs and orlistat with any study design and a mean or median follow-up duration of ≥ 12 months.
  • Qualitative and mixed-methods research on the feasibility and acceptability of lifestyle WMPs and orlistat (including views of professionals involved in care).
  • Economic evaluations (trial analyses and decision modelling studies) of bariatric surgery, lifestyle WMPs and orlistat.
  • Data from the systematic review of RCTs populated a microsimulation model predicting costs, outcomes and cost-effectiveness of the most-effective programmes over a 30-year time horizon from a NHS perspective for a population representative of all adults with a BMI of ≥ 35 kg/m2. The UK Health Forum microsimulation model assessed the cost-effectiveness of:
  • the Look AHEAD trial WMP versus baseline UK general population BMI trends
  • a very low-calorie diet (VLCD) added to a WMP versus a WMP alone, with both versus the baseline UK general population BMI trend
  • Roux-en-Y gastric bypass (RYGB) versus a WMP, with both versus the baseline UK general population BMI trends.

The outcomes were weight change (primary outcome), cardiovascular risk factors, psychological well-being, adverse events, quality of life, process outcomes, qualitative outcomes, costs and economic evaluations.


The reported that bariatric surgery, especially RYGB, produced greater long-term weight change than any of the WMPs [RYGB mean –20.23kg, 95% confidence interval (CI) –23.75 to –16.71kg] at 60 months. Adding a VLCD to an existing WMP gave an additional mean weight change of –4.41kg (95% CI –5.93 to –2.88 kg) at 12 months. Orlistat and dietary counselling reduced weight regain after VLCDs. Long-term weight maintenance after weight-loss programmes that did not incorporate VLCDs was improved by orlistat and follow-up in person or by telephone.

Data analyses initially favoured low-carbohydrate (< 40 g/day) reducing diets compared with low-fat reducing diets (mean weight change of –1.16 kg, 95% CI –2.13 to –0.19kg), and higher protein (≥ 30% energy) reducing diets compared with lower protein reducing diets (mean weight change of –0.91 kg, 95% CI –1.83 to 0.00kg) at 12 months, but not beyond 12 months. The use of meal replacements, such as giving component parts of VLCDs, was associated with greater weight loss, but only at 12 months (mean weight change of –2.75kg, 95% CI –4.01 to –1.48kg).

More intensive interventions, with more contacts with WMP personnel (in person or remotely), were usually associated with greater weight loss and better weight maintenance. Initial inpatient programmes were not associated with greater weight loss. Interventions delivered to groups rather than to individuals had greater weight loss results, but groups usually had more contacts. There was little evidence that incorporating family members for support and modifying the home environment were beneficial. Similarly, interventions that were weight neutral or did not target weight loss were less effective than those with a prescribed calorie content or deficit.

In summary, they reported that:

  • Bariatric surgery had the best long-term weight-loss results and could be a good use of NHS resources, compared with no surgery or weight management programmes on their own.
  • Of non-surgical approaches, very low-calorie diets produced the best weight-loss result at 12 months, but it was unclear if weight-loss was any greater than standard WMPs for longer than this.
  • Adding a very low-calorie diet to an existing weight management programme was shown to not be a good use of NHS resources. However, most weight management programmes, including those with very low-calorie diets, appeared to be a good use of NHS resources compared with doing nothing at all.
  • Low-carbohydrate Atkins-type diets, higher protein intakes or the use of meal replacements had small added effects on improving weight loss compared to other WMPs at 12 months. They also found no evidence that they were better than other diets after 12 months.
  • The best result for long-term non-surgical weight loss (over nearly 10 years) came from an intensive WMP with all of the following: a low-fat reducing diet, a calorie goal of 1200–1800 kcal/day, initial meal replacements or meal plans, a tailored exercise programme, cognitive behavioural therapy, intensive group and individual support, and follow-up by telephone or e-mail. However, this type of WMP would be more costly for the NHS than simpler WMPs.
  • Other components of effective interventions included increasing physical activity to help prevent long-term weight regain and receiving longer-term help with diets or using the drug orlistat. Adding telephone or internet support, and group support, also helped to keep weight off.
  • Participants in weight management programmes valued novelty, weight management programmes endorsed by health-care providers and belonging to a group of people who shared similar issues.

In addition, they noted that weight-management programmes were generally cost-effective compared with a baseline of current UK general population obesity trends [incremental cost-effectiveness ratio < £20,000/quality-adjusted life-year (QALY)]. However, the addition of a VLCD to a WMP was not cost-effective. The Look AHEAD programme was borderline cost-effective compared with current population obesity trends, with an improved case for cost-effectiveness under longer-term weight regain assumptions.

RYGB was the most cost-effective strategy overall in the base-case analysis, over a 30-year time horizon, although the model did not replicate long-term cost savings for surgery suggested by some studies in systematic review. The economic model results were sensitive to assumptions about weight regain, model time horizon and discount rates for costs and QALYs.

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