As GLP-1 weight-loss injections transform the treatment of obesity, an important question remains: are other medical options being overlooked?
More than 2.5 million people in the UK are estimated to have used the drugs. And the results can extend far beyond modest weight loss. A 2024 study published in JAMA found that people taking tirzepatide, the active ingredient in Mounjaro, lost an average of 20 per cent of their body weight over nine months.
Such figures can make the injections appear almost certain to succeed. In reality, however, they do not work equally well for everyone.
Outside tightly controlled clinical trials, an estimated 10 to 15 per cent of people see little benefit from the drugs or fail to respond at all.
That figure does not include those who abandon treatment because of side-effects including nausea and diarrhoea.
Researchers are now investigating why GLP-1 drugs deliver dramatic results for some patients but have limited impact on others.
A paper published in Nature last month explored several possible explanations, including the role of female hormones. Oestrogen may amplify the drugs’ effects, with previous research indicating that pre-menopausal women and women taking hormone replacement therapy lose more weight than men or post-menopausal women who are not on HRT.
Genetic differences are also being examined as a possible influence on how patients respond. At the same time, specialists fear that the popularity of Mounjaro and similar drugs is pushing other effective treatments out of the spotlight. Good Health reported last week on Mysimba, a less expensive weight-loss tablet that may be more appropriate for people with ‘mild’ obesity.
The number of gastric sleeve operations – in which around 80 per cent of the stomach is removed and the remainder formed into a sleeve – fell by 67 per cent between 2023 and 2025
‘We are probably only doing 5,000 to 6,000 bariatric operations a year on the NHS now, compared to 8,000 a year in 2018/2019,’ says Professor Ahmed Ahmed (pictured)
Bariatric, or weight-loss, surgery is another option. Some specialists say it can produce greater weight loss and stronger long-term results, yet its benefits are being eclipsed by the success of GLP-1 injections.
They point out that these procedures can be performed using keyhole techniques, or in some cases without an incision, and may be just as safe as GLP-1 treatment. For certain patients, surgery could be the most suitable choice. However, information about it is being drowned out by the intense focus on medicines such as Mounjaro.
As a result, some people with obesity and serious related illnesses, including heart disease, may be missing out on a potentially beneficial treatment.
The decline in weight-loss surgery has been particularly striking in the UK private sector since the boom in obesity injections began. Some specialist surgeons are even reported to be moving into other fields of medicine as demand falls.
Figures from the Private Healthcare Information Network show that gastric sleeve procedures fell by 67 per cent between 2023 and 2025. During the operation, about 80 per cent of the stomach is removed, leaving it in the shape of a sleeve.
Gastric bypass operations also declined sharply, dropping by 79 per cent. The procedure reduces the size of the stomach and reroutes the intestine beyond the duodenum, the section where calories are absorbed.
The NHS has recorded a similar fall. ‘We are probably only doing 5,000 to 6,000 bariatric operations a year on the NHS now, compared to 8,000 a year in 2018/2019,’ says Professor Ahmed Ahmed, clinical lead for bariatric surgery at Imperial College Healthcare NHS Trust in London and president of the British Obesity and Metabolic Specialist Society (BOMSS).
He says only around 1 per cent of the 4.2 million people in the UK who meet the NHS eligibility requirements for bariatric surgery currently receive it.
Under NHS criteria, patients generally need a BMI of at least 40, or 35 or above alongside an obesity-related condition such as type 2 diabetes. In practice, access to Mounjaro on the NHS is more restricted: patients must have a BMI of 40 or higher and at least four of five specified weight-related conditions.
Surgeons say people with obesity are therefore losing access to a treatment that may offer a more durable answer. Unlike surgery, GLP-1 injections may need to be continued for life to prevent weight regain, and bariatric surgery could ultimately prove less costly for the NHS.
‘While GLP-1s are undoubtedly effective for modest weight loss, some people will still need bariatric surgery because they need to lose more weight,’ says Professor Ahmed. ‘Or they’re one of the 20 per cent of those who don’t respond to the drugs, or they can’t tolerate the drugs’ side-effects. Also the majority of people in the UK on GLP-1s are paying for them out of their own pockets and this may not be sustainable long term, so they may decide to have bariatric surgery instead which offers long-term sustained weight loss.’
Anecdotally, the BOMSS is hearing that confusion over who is eligible for NHS weight-loss jabs is leading some local Integrated Care Boards (which make local funding decisions) to avoid paying for any weight-loss treatments.
Even before the weight-loss drugs came along (their popularity soared after the introduction of Wegovy in 2023), research by the University of Bristol in 2016 estimated that the NHS should perform around 50,000 cases a year – roughly eight times the current number of weight-loss operations – based on obesity levels.
The UK’s bariatric surgery rate is among the lowest in the developed world, with nine to 12 procedures per 100,000 people, despite an adult obesity rate of 28 per cent – significantly higher than France, where 16 per cent of people are obese and 50,000 bariatric operations are performed annually – 72 per 100,000.
Yet bariatric surgery offers as good, if not better, results than weight-loss jabs, says Professor Omar Khan, a consultant gastrointestinal and bariatric surgeon at St George’s University Hospitals NHS Foundation Trust in London. ‘Weight loss after bariatric surgery is around 30 per cent on average over a two-year period and studies show this is mainly sustained in the long term. With GLP-1s the weight loss is significantly lower [around 20 per cent for the older jabs] and this is not sustained unless you keep taking the drugs in most cases.’
GLP-1s, which work by mimicking gut hormones that control appetite, offer benefits beyond weight loss – such as improvements in blood glucose levels and lowering the risk of heart attacks and strokes, slowing the progression of kidney disease or easing obstructive sleep apnoea (which causes breathing to stop temporarily throughout the night).
Yet similar benefits are seen with surgery, some almost instantaneously, argues Professor Khan. ‘If you have bariatric surgery your type 2 diabetes may be resolved within 48 hours.’
He describes its impact as ‘astonishing’ – ‘we see people coming into hospital on 80 to 100 units of insulin a day and they may leave hospital a day later after a gastric sleeve or bypass and they don’t need it any more,’ he says. It’s thought the surgery resets gut hormones.
‘Within three months, 60 to 70 per cent of people have their high blood pressure resolved and two thirds of those with sleep apnoea no longer need a mask at night [known as CPAP, to help them breathe],’ he adds.
Surgery does require lifestyle changes, says Professor Ahmed, for example, all patients have to eat smaller meals. ‘They can still enjoy food, they just get fuller quicker.’
But while most weight-loss procedures can often now be done by keyhole techniques, it is still surgery and recovery takes up to six weeks. There is also the risk of serious complications.
Professor Ahmed acknowledges this, pointing to the National Bariatric Surgery Registry which shows a complication rate of 2.4 per cent – early complications can include infection, wound problems and blood clots.
Longer-term, potential complications include nutrient deficiencies (if advice to take multivitamins is not followed) ‘hernias, and weight regain if follow-up is not adhered to’.
‘In contrast, with weight-loss drugs people get significant nausea, headaches, constipation and diarrhoea – as well as, crucially, muscle loss.
‘One study showed that muscle loss from GLP-1 use can account for up to 40 per cent of the weight loss, but muscle loss from bariatric surgery appears to be lower; under 20 per cent of weight loss,’ adds Professor Ahmed.
One option, an endoscopic gastric sleeve, doesn’t even require an incision – the surgery is done via a tube down the throat, says Dr Rehan Haidry, a consultant gastroenterologist at the Cleveland Clinic, London. ‘It can lead to weight loss of between 15 and 20 per cent and can be done in 60 minutes, and is approved by the regulator, NICE [the National Institute for Health and Care Excellence],’ he says. ‘The trouble is, endoscopic gastric sleeve is only available on the NHS in select centres, and privately it costs £10,000. When you consider that people are paying £3,000 a year for GLP-1s, health economists would argue that a “one and done” procedure may be better value than an ongoing injectable therapy.’
This is a key argument for the surgery proponents.
‘The surgery may cost more in the beginning, but in the long term it’s the cheaper option,’ says Professor Ahmed. ‘Numerous cost-effectiveness studies have demonstrated this when they compared use of GLP-1s long term versus bariatric surgery.’
It costs the NHS £5,000 to £5,500 for a standard bariatric operation such as a gastric sleeve, according to the BOMSS – Professor Ahmed estimates that clinic appointments before and after surgery add another £500 on top.
Bariatric surgery doesn’t work for everyone, but more than 90 per cent of patients lose between 25 and 30 per cent of their body weight, he adds. ‘About 80 per cent of patients maintain this long term – this would be higher but some people stop coming to clinic for lifelong follow-up which then contributes to weight regain,’ says Professor Ahmed.
‘Whilst GLP-1s have transformed how we talk about obesity in this country, the NHS can’t fund them for everyone,’ adds Dr Haidry. ‘We now have a NICE-approved, safe, surgical intervention [a gastric sleeve] that doesn’t require a major operation or a lifelong prescription – and I think that’s where the field has to head over the next few years.’
The fact is, says Professor Khan, bariatric surgery remains the most effective treatment for obesity – particularly for those with a BMI of 50 and above.
‘As effective as GLP-1s are for some, they don’t lead to sufficient weight loss for very obese patients,’ he says. ‘Based on what I see in clinic, if your weight is extremely high, even a 20 per cent weight loss will not be enough to put you in a healthy weight range so you will continue to suffer health detriments, including reduced life expectancy.’
Of course, surgeons are in the business of operating. But they say their argument is not about everyone having surgery – rather that this other option is being drowned out. ‘There is no one banging the drum for surgery in the same way as there is for weight-loss medication – as a surgeon, my marketing budget for bariatric surgery is zero,’ says Professor Khan. ‘But pharma companies behind GLP-1s have billions to spend.’
And there are other options besides weight-loss jabs and surgery available on the NHS, such as the Type 2 Diabetes Path to Remission Programme – you qualify if your BMI is over 27, or over 25 if you are black or of Asian origin. It consists of a 12-week plan of soups and shakes only, which provide 800-900 calories a day, followed by support to ‘reintroduce healthy, nutritious food’.
In a key trial published in 2018, participants lost over 10kg and a year later had maintained it, while almost half put their type 2 diabetes into remission.
This option, too, is being overlooked, say experts. Awareness of GLP-1s ‘inevitably shapes the conversation around obesity treatment,’ says Jack Doughty, a spokesperson for the Obesity Health Alliance, a coalition of 70 health organisations.
‘The NHS has a legal duty to fund NICE-approved medicines for eligible patients, whereas the same obligation does not apply in the same way to other forms of weight-management support.
‘So GLP-1s are undoubtedly capturing more of the nation’s attention in a way other treatments haven’t, but they should still be seen as one part of a broader range of treatment options.’
But could the pendulum soon swing the other way?
Alexander Miras, a professor of endocrinology at the University of Ulster and a leading obesity expert, said a drop in demand for bariatric surgery was inevitable with the introduction of GLP-1s.
‘Most people would prefer taking a medication over having an operation, of course – even surgeons don’t want to have surgery if they can avoid it,’ he says.
‘But – and there’s a big but. Firstly, access to and sustainability of these medicines is very limited. In the NHS, only a very small proportion of patients are being treated and therefore most people are having to pay for it – and this is difficult to sustain long term. Secondly, the drugs don’t work for everyone – according to a 2022 trial about 10 per cent of people – and another 10 to 15 per cent have side-effects so don’t continue to take the drugs.’
Professor Miras says in Norway, where GLP-1s were available earlier than in the UK, demand for bariatric surgery is rising again after an initial drop.
‘Bariatric surgery is a permanent solution to obesity,’ he says.
Professor Ahmed is trying to get funding for a trial comparing the outcomes for obese patients on injections or after surgery, measuring quality of life, weight loss, health benefits and costs.
‘The NHS needs to know this information,’ he says. ‘There is huge hype with GLP-1s, not least driven by the pharma companies marketing the drugs. But we have scarce resources and need to know which is most cost effective and most clinically effective.’
Bariatric surgery ‘could offer better long-term value for the NHS than paying indefinitely for repeat prescriptions,’ adds Jack Doughty. But ‘it is not a magic bullet and nor are the GLP-1 medications’. ‘If we are serious about improving the nation’s health, treatment has to go hand in hand with prevention,’ he says.
I didn’t shed a single pound on Mounjaro but lost 8st after op
After a gastric bypass surgery, Amanda Forster was down from 19st 4lb to 11st, her current weight. She says she’s proof GLP-1 drugs don’t work for everyone
After three months on Mounjaro, Amanda still hadn’t lost a single pound, despite hoping that the jabs would end ‘food noise’ for her (pictured before her weight loss)
Amanda Forster, 58, who runs a flag manufacturing business with her husband Neil, 59, lives in County Durham. They have three children between them and one grandchild. She says:
When Mounjaro became mainstream two years ago I thought my prayers had been answered.
I had battled my weight all my life and at that point weighed over 19st (I’m 5ft 2in, meaning my BMI was over 50).
I was convinced I had an addiction to eating. I could eat a full pack of biscuits and still not feel full and was always snacking. I had no ‘stop’ switch.
So hearing the jabs could end ‘food noise’, I thought ‘yes, finally!’ I bought some privately from an online clinic and started injecting on a dose of 2.5mg, which I then increased to 5mg.
But a month passed, then three. The jabs had no side-effects at all, but I didn’t lose a single pound. I seemed resistant to their effects.
I’d tried so many weight-loss methods over the years: WeightWatchers, Slimming World, the cabbage soup diet, even herbal appetite suppressants. So when I also failed with the jabs, I feared nothing would work for me.
I was at my heaviest, 19st 4lb, five years ago. My BMI was 51 and I was finding it hard to walk up stairs without getting breathless. I also developed high blood pressure and my joints ached.
I wanted to see my children and grandchild grow up, so I finally asked my GP for help – and had a gastric band [where a device is placed around the top of the stomach to limit food intake] on the NHS. I was scared, but I thought that would solve everything.
It didn’t. I could still eat a full three-course meal. No weight came off at all and a year later I had it removed. I was told it could be refitted, but it seemed the wrong choice for me. My appetite barely changed.
Over the next few years I went back to trying every diet going – but I never lost a pound. Then, in December 2024, a few months after I’d tried the weight-loss jabs, two of my friends had bariatric surgery and lost several stone.
So I went to see their surgeon, Zaher Toumi, at the Spire Washington Hospital. He suggested a gastric bypass [where the stomach is reduced in size, and part of the small intestine is rerouted] would be my best option.
I had the surgery that month; it cost me £16,000. I was in one morning and out the next day. I had no complications and as the weeks passed, for the first time ever, the weight fell off.
Within two months I’d lost several stone. I was never starving, I just ate smaller portions.
I worked closely with a nutritionist from the hospital and had regular calls from Mr Toumi. Within a year I was down from 19st 4lb to 11st, my current weight.
Mr Toumi explained that some people just don’t respond to weight-loss jabs and that a gastric band is also limited because it’s purely mechanical – while a bypass doesn’t just restrict intake, it resets your appetite hormones.
I feel well and I am not getting out of breath like before. And shopping for clothes for my daughter’s wedding last year was an absolute joy. I was able to buy a size 12.
GLP-1 drugs are hailed as miracles but I’m proof they don’t work for everyone. Surgery sounds drastic but it was the only thing that worked for me.
Interview by Julie Cook
