It was about a year ago that Del O’Sullivan got the bad news. “The doctor rang me up and said, ‘You won’t see 50,’” he recalls. At the time O’Sullivan, a 47-year-old single dad from Harrow, weighed more than 19 stone. He was suffering with high blood pressure, extremely high cholesterol, and type-2 diabetes. His BMI was so high that he was categorised as Class III — that is, dangerously — obese.
O’Sullivan’s GP, he says, raised the prospect of gastric band surgery — a permanent and serious intervention. Or, he suggested, he could try a new class of weight-loss drugs: the glucagon-like peptide agonists, or GLP-1, drugs tirzepatide (sold as Mounjaro) or semaglutide (Wegovy/Ozempic). There was a catch. At the time, the drugs — which work by suppressing users’ appetites — were not available via the NHS.
He remembers being confused. “You’re telling me to go on it, but you won’t give it to me?” O’Sullivan, who is not working because of poor health, was desperate, and in May 2025, he paid for his first dose of Mounjaro.
Eight months later, he has lost 30 pounds. His diabetes is in remission; and his BMI has fallen from 47 to 33. Even his mental health — he has bipolar disorder — has improved. “It’s done wonders for me,” he says.
But he is struggling financially. “I’m behind on every bill because of it,” O’Sullivan says. In September, Eli Lilly increased the UK price of Mounjaro by 170%; it is now £330 per month for the highest dose. “I have to make choices every month with food, electric. I’ve got two dogs. What do you do?”
His story is not unusual. There are now 2.5 million British people — nearly one in 20 adults — taking weight-loss drugs. That figure has doubled in a year, even in the face of supply shortages and price hikes. Given those are figures from July 2025 and do not include the black market, the true number is likely already much higher. “Anyone who says they anticipated this is lying,” says Prof. Giles Yeo, an obesity expert and professor of molecular neuroendocrinology at Cambridge University. “Not even the drug companies.”
Arguably not since the pill has a medication changed society so widely, so fast. Grocery sales have fallen by an estimated £136 million per year. Alcohol sales are also down, with three-quarters of GLP users cutting back, according to research by Kantar. Restaurants from the Fat Duck to Greggs are introducing smaller-sized “Mounjaro menus”, while supermarkets from the Co-Op to Marks & Spencer have launched “nutrient dense” ranges for those on the jabs. The clothing industry is enjoying a surge in sales of smaller sizes, as users adjust their wardrobes. Tirzepatide manufacturer Eli Lilly, meanwhile, has doubled its profits and tripled its stock price, recently becoming the first healthcare company to be valued at $1 trillion.
But not everyone is seeing the benefits. Fewer than 200,000 patients currently receive tirzepatide through the NHS, due to a combination of strict prescription guidelines and challenges accessing funding. NHS England is phasing in GLP1-s for weight loss over several years; currently only patients with a Body Mass Index (BMI) of 40 and multiple comorbidities (such as diabetes, heart disease, and sleep apnea) are eligible. That’s a tiny fraction of Britain’s estimated 18 million obese people. Everyone else must pay privately: in many cases over £3,300 per year, which makes up nearly 10% of the UK’s average salary. For many, that price is too high.
O’Sullivan has been posting on YouTube about his Mounjaro journey. Through his followers, he has seen the drugs changing other people’s lives. “I have friends on it who have stopped drinking,” he says. “A few people gave up smoking.”
But since the price hike, he says, many have had to cut back, or give up entirely. “I speak to loads of subscribers and they’ve had to stop,” he says. “People who are working and they have families, and they just can’t [afford it]. It’s heartbreaking. It’s changed their life, and now they’re back to eating again.”
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Nearly two-thirds of British adults are obese or overweight, according to the NHS. Those on low income are more likely to be overweight — women from the most deprived areas, for example, are twice as likely to be obese than those from the most affluent ones. Naveed Sattar, professor of cardiometabolic medicine at the University of Glasgow and Chair of the government’s Obesity Healthcare Goals programme, tells me that 25 years ago, he considered obesity was a major factor in around one in 20 patients. “Now I’m seeing it in four in ten, five in ten,” he tells me. The complications multiply: “More people with diabetes or prediabetes, more people with high blood pressure, fatty liver disease, more people with arthritis, knee pain, sleep apnea.”
GLP-1s are not only helping tens of millions of people lose weight; they are also creating a cultural shift in our understanding of obesity. If hunger is not a question of willpower, but a function of hormones — dictated by genetics, and tweaked with a simple injection — then moral judgements about obesity now look outdated. Instead, we are now starting to reexamine the roles of our food system and environment, both of which make it harder for people on lower incomes to be healthy.
“You’re up against it from multiple levels,” Sattar says. Poorer people tend to have more limited access to outdoor spaces and exercise, additional psychosocial stress, and less time to cook. Shopping at Waitrose and farmers markets also costs considerably more than fast-food or ready meals. According to research by the Food Foundation, merely following the NHS’s healthy eating guidelines would cost the average person on low wages 50% of their disposable income. “I’ve got to eat chicken and fish and steak and fresh vegetables now,” O’Sullivan says, darkly. “It was cheaper on frozen pizza.”
To date, the conversation around GLP-1s has often framed them as a luxury lifestyle choice — “skinny shots” taken by celebrities and the vain middle class wanting to look better on social media. But for the dangerously obese, particularly those on low incomes, these are life-saving medications for a life-threatening disease. Only right now, they are being priced out of the cure.
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Excluded by the NHS and priced out of private healthcare, many Britons are getting the jabs by less legal means. On TikTok and Instagram, I was able to find sellers touting black market GLP-1s with a simple search. “There are all these different labs in China producing these chemicals,” explains Luke Turnock, a criminologist at the University of Lincoln who studies illicit performance-enhancing drugs, including GLPs. “Bodybuilders, who were using growth hormone-stimulating peptides, got very used to buying peptide vials in powder form, reconstituting them, and selling them within gyms. So when this massive interest in GLP-1s blew up, a lot of these peptide sellers said: ‘Let’s pivot to selling GLP-1s.’”
The black market is now outstripping the health system’s ability to keep up. On social media, many users boast of using retatrutide, an as-yet-unreleased triple-action weight-loss drug being developed by Eli Lilly. Although the platforms have attempted to limit mentions of GLP-1s, it took me minutes to find users openly talking about taking “reta” or tirzepatide — as well as phone numbers or links to WhatsApp or Telegram groups offering to sell it. Turnock noticed an uptick of interest in retatrutide in 2024. “It absolutely took over, because it’s ‘Oh, we can get this cheaper than legitimate prescription ones, and it’s said to be more effective.’” (In clinical trials, retatrutide has shown greater weight loss effects than similar-length trials of tirzepatide, and twice that of patients on semaglutide.)
Fraud is rife. One study of black-market weight-loss drugs found that, if they did contain the active ingredient, they sometimes contained wildly incorrect doses. “Some of them were as low as 14% [of the listed dose] and some were 139% of what they should be. So there are obvious potential risks,” Turnock says. On social media, some influencers have reported their accounts being cloned or hacked by black-market sellers, looking to push products to their large audiences.
Marc McKee, a weight-loss influencer who has built up more than 91,000 followers on Instagram through sharing his journey on GLP-1s, has lost over nine stone in less than a year on Mounjaro. After the September price hike, he watched as his followers were drawn to the black market. “Somebody messaged me that they had injected themselves. They were actually in hospital, and wanted me to put out a warning,” he says. “They’d injected themselves with expired insulin.” Some patients have been hospitalised; at least one has died. “You have no idea what you’re putting into your body,” says McKee.
Even when black market drugs do contain the promised active ingredient, there are still risks. “Because we haven’t had the clinical studies, we don’t actually know the correct dosing of retatrutide,” says Turnock. “Online you’ll hear people say, ‘this is what you should be dosing reta at.’ That is just essentially based on supposition and some experimentation.” As it is still in clinical trials, retatrutide’s side effects are not clearly known, but some users report serious complications.
One of the challenges with GLPs, Turnock says, is that many customers don’t understand the difference between licensed online pharmacies and unlicensed sellers — or are willing to look past them in their desperate search for cheaper drugs. “A lot of them might not even see themselves as ‘I’m engaging with a black market’,” he says. “They just see this as, ‘it’s being advertised, I’ll access it.’”
McKee has started a petition, urging the government to further reduce the price of medications like Mounjaro, in order to make access more equitable. It has reached over 7,000 signatures. He advises his followers to stay away from them, and advocates that people considering peptides do so legally, and only for health reasons. “There’s people that are trying to get it that maybe shouldn’t.”
“What does that tell us?” says Yeo, of the black-market explosion. “It tells us about our obsession with ‘weight equals beauty’. At the other end of the spectrum: that people really need the drug, and are desperate.”
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Talking to patients, it’s clear that GLPs are transformative for many people who have struggled with their weight, and with it their health and even their sense of self, for most of their lives. “My knees were starting to hurt, my blood pressure was increasing. I’d tried to lose weight, but the biggest thing for me was emotional eating,” says Ese, 36, from Bedford. She had tried numerous times to lose weight, including signing up to the NHS weight-loss programme, but didn’t find it effective. Then she started Mounjaro. “I literally forgot to eat,” Ese says. “It was like the food noise had vanished.”
McKee tells a similar story. “I’d gone through multiple different health problems: my liver, kidneys, high blood pressure, cholesterol, all that stuff was all really, really high,” he says. “For me it was never about looking better. It was more about being healthier.” McKee is now in the best shape of his life. “My blood pressure came down, my liver function came back, same with kidneys, cholesterol, everything.”
There is also growing evidence that GLPs have additional benefits beyond treating diabetes and weight loss, lowering the risk of heart disease, kidney disease, and possibly even cancer. (A trial testing semaglutide to treat Alzheimer’s disease, however, failed.) There is also anecdotal and pretrial evidence that GLP-1s may be effective in the treatment of serious addiction.
Given their benefits, and the risk of the black market, some experts believe that GLP-1s could — and should — be rolled out more widely. “Only the most severely ill people are getting it [on the NHS] at the moment,” says Yeo. “We could be benefitting many other people as well. From a health economics perspective, it’s a no-brainer, right? Roll it out as quickly as possible to people who need it.”
Sattar agrees. “We need to think how we can cut our costs to get more people on the drugs faster.”
Doing that, however, is complicated. When the UK’s National Institute for Health and Care Excellence (NICE) — which decides which medications should be available through the NHS — ruled on tirzepatide, its findings were mixed. Although it agreed that tirzepatide is safe and effective for weight loss, it found that the benefits of the treatment did not reach its cost-effectiveness thresholds, judged in cost per quality-adjusted life year (or QALY) gained, except in those with extreme obesity-related health difficulties — hence the NHS’s cautious rollout.
The NHS has a confidential commercial arrangement with Eli Lilly to buy Mounjaro at a discounted rate. Currently, the NICE ruling for tirzepatide includes factoring in numerous costs — such as diet and exercise counselling, and psychological support for a third of patients — that most people do not get when paying privately. (“Most of them we don’t need,” Sattar says.) And in December, as a result of the UK-US trade deal, the UK finally raised the threshold it is willing to pay for innovative drugs by 25%. Given the growing evidence for their benefits, therefore, there is a case that NICE look again at its guidance, which is currently under review.
But GLP-1s are expensive, and, thanks to pressure from the Trump administration, only getting more so (in effect, the Mounjaro price rise was Eli Lilly bringing UK prices into alignment with US prices). Calculating their benefits for the healthcare system (in preventing costly treatments for other diseases) and economy (in getting healthy people back to work) is difficult, because studies show that most users regain the weight lost — and the associated health risks — within three years of coming off the drug. They also require constant treatment, whereas gastric band surgery is one-off, and permanent.
Besides, Sattar told me, even if lowering diabetes-related complications, such as heart and liver disease, did bring substantial cost-savings, the up-front cost of buying that many drugs is currently simply too prohibitive. “It will save a lot of money, but it won’t save it that quickly,” Sattar says. “Cost effectiveness only matters when you’re talking about a few hundred or a few thousand [patients]. When you’re starting to talk about a drug that 10 million could take, and the cost is so high, you can’t afford it.” In other words: there are simply too many obese people in the UK for the NHS to treat them all.
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Nevertheless, 2026 might be the year that the scales start to tip. Although the patents for the early GLP-1s are valid until at least 2031 in the UK and US, the patent for semaglutide (Wegovy/Ozempic) expires this year in China, Brazil, India, Turkey, and Canada — that is to say, in some of the biggest generic medication manufacturing countries in the world. If we think the black market is big now, it’s about to be supercharged — not with knock-offs, but with cheap generics.
There are also around 100 new weight-loss drugs in development, including retatrutide, which could be approved in some markets towards the end of this year. One of those new drugs, Orforglipron — also owned by Eli Lilly — is a once-a-day pill, rather than an injectable, and therefore likely to be cheaper to manufacture, as it does not require refrigeration. “The hope is in the next three or four years we might get four or five more drugs licensed, and then it’s competition and the prices come down,” Sattar says.
When that happens, the consequences for society will be profound. “Candy, beverages, alcohol, they are the most impacted,” Leigh O’Donnell of Kantar Research, which has done large surveys of GLP-1s’ impacts, told me. “71% of British respondents said that they were consuming less alcohol since they began the drug; 45% of folks said that they are consuming less tobacco.” Numerous industries — sugary foods, fast-food, restaurants of all kinds — will be disrupted. Other impacts, such as widespread anecdotal reports of users suffering from reduced libido, or giving up addictive behaviours, are yet to be clearly understood.
“The interesting question to ask is: is this a way of actually beginning to reformulate our food environment?” says Yeo. One outcome could be that, if enough people go on GLPs, everyone benefits.
Sattar agrees. “My sense is that as more people come on these drugs, we will see slow, subtle evolutions of the food and drinks industry,” he says. “I hope it goes in the right direction: less fast food, smaller portions, better quality foods, less highly dense. But that’s being optimistic.”
Still, a world of ubiquitous weight-loss drugs still comes with risks. “My main issue I have is that there is no limit for when you begin to respond to the drugs,” says Yeo. “If you’re a 350-pound man looking to lose 100 pounds, excellent, this drug is designed for you. But it will also work for a 16-year-old girl who’s 70 pounds. And that is the problem. You don’t have to go that far onto the other end of the scale when it becomes dangerous.”
Most of the people I spoke to taking weight-loss drugs are planning to stop eventually. “I’d like to come off it,” O’Sullivan told me. “To be able to get back to normal, go back to work, not be broke all the time. That’d be great.” But he still has a way to go. Until then, unless NHS guidance changes, he will have to keep making sacrifices to pay for it.
“I know eventually when I do come off, my appetite may come back,” Ese tells me. “My plan was never to do Mounjaro for life. [But] I’m not at my goal weight, and I’ve had so many people go on Wegovy and they have regretted going on it, and then they’re coming back to Mounjaro.”
McKee has already taken one break from Mounjaro, and hopes to quit soon. He has been working on his fitness and diet, and building healthy habits, so that he can maintain his new weight for good. “I think when you put all that work in,” he says, “You never want to get back to being that person.”
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