Weight loss medication after bariatric surgery: is it an option?

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Many experience weight regain after bariatric surgery. Are weight loss injections the answer? Let's find out.

Bariatric surgery is a type of operation that helps a person lose weight. It usually involves removing or sealing off part of the stomach. This restricts food intake, limits nutrient absorption or both.

It's not for everyone – and like all types of surgery, it comes with risks. However, thanks to modern surgical techniques, it's now considered a relatively safe and routine operation. Each year, around 7,000 people in the UK undergo bariatric surgery.

It's also considered – along with injectable weight loss medications – to be one of the most effective ways to treat and manage severe obesity. One study saw bariatric surgery patients lose, on average, 72.4% of their excess weight after three years.

However, no treatment is foolproof. Weight regain after bariatric surgery is not uncommon – and the risk of gaining weight appears to increase with time.

Are weight loss injections like Wegovy and Mounjaro the solution? Could these modern drugs provide a safe and effective way for bariatric surgery patients to manage their weight in the long term?

Recent studies suggest the answer might be 'yes'. But before we dive into the details, let's consider the situation as it stands. How common is weight regain after surgery, and what options are currently on the table for patients who need help managing their weight?

The problem of weight regain

Let's be clear. Bariatric surgery can – and often does – have profoundly positive outcomes for people living with severe obesity.

For many patients, it proves to be the only effective way to achieve long-term weight loss after years of failed diets and exercise regimes. It can drastically enhance a person's quality of life. It can increase life expectancy. And it can help improve or reverse a raft of weight-related health conditions, including high blood pressure, arthritis and type 2 diabetes.

But despite all these benefits, the spectre of weight regain looms large over bariatric surgery patients and the experts who treat them.

Picture of a person stepping on a scale.

It's hard to know for sure how pervasive the problem is – partly because experts disagree on what 'weight regain' really means. However, a 2016 clinical review observed rates of weight regain ranging from 5.7% after two years to as much as 75.6% after six years.

More than 75% of patients is nothing to sniff at. But it's important to note that this represents the highest estimate of a problem that's notoriously difficult to quantify.

And – just as importantly – doctors have developed ways to address it.

Diet and exercise interventions, for instance, can prove effective – especially for patients who may have slipped back into old habits. However, this option requires great willpower and doesn't work for everyone.

Another option is revision surgery – or, to put it more bluntly, operating all over again. Doctors most often take this route when surgery hasn't achieved the expected results. Usually, it means carrying out a different surgical procedure to 'replace' the first one – and, hopefully, getting better results the second time around.

Revision surgery can be highly effective. However, it's not an option to take lightly. Like any form of invasive surgery, it comes with baggage: disruption to daily life, a period of recovery and a small amount of risk.

The issue, then, is not that we lack therapeutic options. It's that we lack therapeutic options that can be applied broadly, easily and effectively. The ideal option would work for most patients, most of the time, and involve minimal risk or disruption.

That's where weight loss injections may be able to help.

Is weight loss medication after bariatric surgery the answer?

Wegovy and Mounjaro belong to a class of drugs called 'incretin mimetics' or 'GLP-1 receptor agonists'. They work by slowing digestion, making us feel full for longer and reducing food cravings.

The benefits of these medications for weight loss are well-documented. When prescribed by a doctor and taken according to a medical weight loss plan, Wegovy results in an average of 15% weight loss.⁴ Mounjaro is even more effective, resulting in 21% weight loss on average.

At first glance, Mounjaro and Wegovy appear to fulfil all the criteria for the ideal weight management solution after bariatric surgery:

They're considered safe and effective when prescribed by a doctor.
Broadly speaking, they're non-disruptive. Patients only need to take one dose per week, and most experience only mild side effects.
Many people qualify for treatment. In the UK, patients must have a BMI of 30 or above – or at least 27 if they have a weight-related medical condition.

However, treating obesity and managing weight regain after surgery are two different things. More research is needed before weight loss injections can be rolled out en-masse as a post-surgery weight management therapy.

The good news is that research is underway – and the results are already painting a positive picture.

In a recent small-scale study, participants who had experienced weight regain after bariatric surgery were treated with semaglutide (Wegovy) or liraglutide (Saxenda). On average, the participants lost 99.3% of the weight they'd put back on – and the researchers concluded that the treatment was safe and effective.

This paper builds on previous research published in 2021. In that study, researchers compared three therapeutic options, including GLP-1 medications. They found that participants in the GLP-1 group lost the most weight (6.9% of total body weight).

These studies represent – we hope – the first fruits of what will become an abundant body of research. At the moment, however, there is no broad consensus on whether weight loss injections are the right option for weight regain.

If you've had surgery and are interested in trying them, the best thing to do is to talk to your healthcare provider about your options. They can look at the facts and recommend the best course of treatment for you.

SemaPen offers proven and effective weight loss plans using the injectable medications Wegovy and Mounjaro. Why not learn more about our unique, expert-led programme?

Sources

1. https://bomss.org/introduction-page-bariatric-surgery-the-long-term-health-benefits-and-potential-complications/

2. Alfadda, A.A. et al. (2021) "Long-Term Weight Outcomes after Bariatric Surgery: A Single Center Saudi Arabian Cohort Experience" Journal of Clinical Medicine, 10(21) https://doi.org/10.3390/jcm10214922

3. Lauti, M. et al. (2016) "Weight Regain Following Sleeve Gastrectomy-a Systematic Review" Obesity Surgery, 26(6) https://doi.org/10.1007/s11695-016-2152-x

4. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

5. Jastreboff, A.M. et al. (2022) "Tirzepatide Once Weekly for the Treatment of Obesity" The New England Journal of Medicine, 387(3) https://doi.org/10.1056/NEJMoa2206038

6. Jensen, A.B. et al. (2025) "Efficacy of 12 months therapy with glucagon-like peptide-1 receptor agonists liraglutide and semaglutide on weight regain after bariatric surgery: a real-world retrospective observational study" BMC Endocrine Disorders, 25(93) https://doi.org/10.1186/s12902-025-01913-4

7. Gazda, C.L. et al. (2021) "Pharmacotherapies for Post-Bariatric Weight Regain: Real-World Comparative Outcomes" Obesity, 29(5) https://doi.org/10.1002/oby.23146

This article was reviewed and approved by Alice Fletcher, Lead Bariatric Dietician, and Lujain Alhassan, Bariatric Nutritionist, on 20 May 2025.

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