What is the failure rate after weight loss surgery?

June 29, 2021



By Mr Andrew Smith (Surgeon)

This sounds simple to answer, but it’s actually really complicated!  There are different surgeries.  How do you define ‘failure’?  Also, with weight loss surgery, together we are tackling a complex opponent, namely obesity, which has genetic, environmental, physiologic and psychological drivers.  No matter what we do to try to lose weight, our bodies have multiple mechanisms to sabotage our efforts.  We all know how hard it is to lose weight, and if we succeed, it’s even harder to keep it off.  Our body can adjust it’s basal metabolic rate, and this slows down when we are consuming fewer calories.  It stays slower than it was before when the diet is abandoned, leading to rapid weight gain, and some further increase (yo-yo dieting).  Even our motivation to stick with a diet is eroded by our body’s physiology.   Despite this, surgery is the most effective tool that we currently have.

But back to the question, with those complexities in mind, a common definition of failure is loss of less than half of a person’s excess weight (%EWL is excess weight carried above a Body Mass Index of 25kg/m2).  Most of my patients express disappointment if they’ve only had 50% excess weight loss, but the reality is that even surgery has limited power to assist a person to manage their weight.

Additionally, all surgeries are most effective in the first five years, and less effective after that.  And obtaining reliable data about follow up for more than 5 years after surgery has always been very difficult.


Operation Failure Rate at 5 years Success Rate
Lap-banding About 30% Mean weight loss at 10 years is 49% of excess weight
Sleeve Gastrectomy About 20% Mean weight loss at 10 yrs is 55-60% of excess weight
Gastric bypass About 20% Mean weight loss is 10 yrs is 55-60% excess weight


Another definition of failure is that the surgery is reversed (eg removal of a gastric band).  Different studies have different rates of band removal, depending on the enthusiasm of the surgeon to persist with the band, but it is generally 20% of cases.  In our clinic it is about 6%.

Another reason to consider an operation to have failed, is the need to do further surgery because of side-effects, eg a bypass after a sleeve for severe reflux.

Whilst this is all discouraging, a problem with these definitions is that they don’t recognise that there are often significant health benefits and improvements in quality of life with less weight loss, For instance, excess weight loss of 30%, that might be classified as a ‘failure’ may result in resolution of diabetes, high blood pressure or sleep apnoea.  The patient experiencing these health benefits may not consider their results to be a failure at all!

Additionally, there is no doubt that on average a patient will have a longer, healthier life after weight loss surgery than if they didn’t have it done.

We would love to be able to predict those patients who will fail with bariatric surgery, but this has never been possible with medical or psychological assessment.

But if you want to maximise the chances of success, there is no doubt that seeking to have your care managed in a clinic with a multidisciplinary team will improve your chances.  Weight loss surgery is not the complete answer.  It also requires education, follow-up, ongoing nutritional assessments, dietitian input, and often psychological support to get the best results.

*Reference Obesity Surg 2019 Jan;29(1):3-14, P. O’Brien et al “Long-Term Outcomes After Bariatric Surgery: a Systematic Review and Meta-analysis of Weight Loss at 10 or More Years for All Bariatric Procedures and a Single-Centre Review of 20-Year Outcomes After Adjustable Gastric Banding.”



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