Are Weight Loss Injections Safe in the UK Everything You Need to Know Before Considering Ozempic, Wegovy or Mounjaro in 2026-part2

     What the safety discussion too often omits, however, is the question of what happens when these drugs stop working either because someone stops taking them or because the body eventually reaches a plateau. A 2026 meta-analysis published in the British Medical Journal, led by researchers at the University of Oxford, reviewed 37 studies involving 9,341 people and found that participants lost an average of 14.7 kilograms over approximately 39 weeks on newer weight loss medicines including Wegovy and Mounjaro. 

Are Weight Loss Injections Safe in the UK Everything You Need to Know Before Considering Ozempic, Wegovy or Mounjaro in 2026

     After stopping these drugs, they regained around 0.8 kilograms per month a trajectory that the researchers predicted would return most people to their original weight within 18 months of starting treatment. Research from the University of Cambridge confirmed that a year after stopping GLP-1 medications, people regain on average 60% of the weight they lost, though weight regain appears to plateau after this point, with individuals managing to keep off roughly 25% of total weight lost. Eli Lilly's own STEP-1 trial extension showed participants regaining roughly two-thirds of lost weight within 12 months of stopping semaglutide. 

      A real-world analysis from Cleveland Clinic involving nearly 8,000 patients offered a more nuanced picture, finding that many people who stop these drugs in clinical practice as opposed to in controlled trials manage to maintain more of their weight loss because they restart treatment, switch medications, or have embedded lifestyle changes during the treatment period. That last clause is critical. Research consistently shows that without the concurrent development of sustainable habits around food, exercise, and sleep during the treatment period, most people will regain weight once the medication stops acting as what University of Cambridge researchers memorably described as a "brake on appetite."

     There is also an underreported side effect that disproportionately affects people who lose weight rapidly on these drugs: the loss of lean muscle mass alongside fat. Research published in January 2025 estimated that as much as 40% of all weight lost on GLP-1 medications can be lean muscle rather than fat. This process visible in the face as what has become colloquially known as "Ozempic face," characterised by hollowness around the cheeks and a looser-skinned, more gaunt appearance is not merely cosmetic. Loss of muscle mass reduces metabolic rate, weakens balance and movement, affects bone density, and can contribute to sarcopenia in older patients. When people who have lost significant muscle on GLP-1 medications then stop treatment and regain weight rapidly, the weight they regain is predominantly fat meaning they may end up with a worse body composition than before they started, even if their total weight returns to a similar level. This is why every credible clinical guidance document from NICE to the NHS England weight management injection pages to the British Heart Foundation emphasises that these medications must be used as part of a programme that includes dietary support, regular physical activity, and behavioural change, not as a standalone pharmaceutical intervention. 

     Mounjaro costs the NHS £122 per month at its maximum maintenance dose. Privately, the cost of Mounjaro rose by up to 170% when Eli Lilly increased UK list prices in September 2025, making Wegovy the more cost-effective option for many private patients. For anyone paying out of pocket without medical supervision, these are not small decisions financial, physical, or psychological.

     The future direction of this space will arrive faster than most people realise. A pill version of Wegovy containing semaglutide was launched in the United States in early 2026, and while it has not yet been approved for use in the UK, it is currently under review by the MHRA. Retatrutide a triple-hormone agonist targeting GLP-1, GIP, and glucagon simultaneously delivered average weight loss of up to 71.2 pounds in clinical trials announced by Eli Lilly in December 2025, which would make it substantially more powerful than any currently available treatment. 

    These next-generation drugs are entering a landscape where the NHS's phased rollout of Mounjaro is still in its earliest stages, where waiting lists for specialist weight management services in England stretch up to two years, where Northern Ireland has not yet opened its first specialist weight loss service, and where the gap between what these medications can achieve and who can safely and legally access them remains wider than any headline number suggests. The policy challenge for the UK government, NICE, and NHS England in 2026 and beyond is not whether these drugs work the clinical evidence for that is now overwhelming but how to ensure that those who need them most can access them safely, with appropriate medical oversight, without being driven toward a black-market pen filled with an unknown substance because the NHS list is too long and TikTok is too persuasive.