An estimated 1.6 million adults in England, Wales and Scotland used drugs such as Wegovy and Mounjaro to help lose weight between early 2024 and early 2025, according to a new study by UCL (University College London) researchers.
The research, published in BMC Medicine and funded by Cancer Research UK, found that an additional 3.3 million people said they would be interested in using weight loss drugs over the next year.
The team looked at data from 5,260 people who were representative of the general population and who responded to a survey conducted in early 2025.
They found that use of the drugs was twice as common among women compared to men and more common among people in middle age (aged 45-55), and those who reported psychological distress in the past month.
The team also found that levels of use were similar across social grades, but that interest in using drugs to support weight loss in future was greater among more typically disadvantaged groups (among whom obesity is more prevalent), suggesting a demand not currently met by private prescriptions.*
Lead author Professor Sarah Jackson, from the UCL Institute of Epidemiology & Health Care, said: "Our findings show that an estimated 4.9 million adults in Great Britain – nearly one in 10 – have recently used a drug to support weight loss or were interested in using one in the near future.
"This usage far exceeds NHS England's initial goal of prescribing these drugs to 220,000 people over three years.
"We do not know about our survey respondents' BMI or health conditions, so it is not clear how far this reflects a genuine medical need or how often the drugs are used unnecessarily by people of a healthy weight.
"We hope to gather more detailed data in future, monitoring how trends change over time. Good data are important as large numbers of people are taking these drugs outside medical supervision and there is wide potential for misuse. NHS prescribing data only captures a small part of the picture."
Co-author Professor Clare Llewellyn (UCL Institute of Epidemiology & Health Care) said: "Weight-loss drugs like GLP-1 agonists could play an important role in improving the health of the nation. Our findings suggest many people are accessing these medications outside the NHS. This raises concerns about equity given the costs of these drugs, as well as the adequacy of supervision of treatment."
For the study, researchers used data from the Smoking Toolkit Study, an ongoing survey that interviews a different sample of adults in England, Wales and Scotland (but not Northern Ireland) each month, who are representative of the country's general population. Questions relating to weight loss medications were added to three months of questionnaires (January-March 2025).
Survey participants aged 18 and over were asked about their use of five medications: Mounjaro (containing tirzepatide), Ozempic, Wegovy, Rybelsus (all three containing semaglutide) and Saxenda (containing liraglutide).** Most respondents taking medication solely for weight loss (four out of five) reported using Mounjaro.
Overall, 4.5% of participants reported using one of the medications in the past year for any reason; 2.9% reported using them for weight loss (i.e., an estimated 1.6 million people), while 1.7% reported using them exclusively for weight loss (equivalent to 910,000 people) i.e., they did not use them for an additional reason such as to lower heart disease risk or regulate blood sugar levels for type 2 diabetes.
Use of the medications to support weight loss was higher among women than men (4% vs 1.7%) and higher among those of middle age (4.2% of 45- and 55-year-olds compared to 1.2% of 18-year-olds and 1.5% of 75-year-olds***).
Prevalence was higher among those who reported moderate or severe psychological distress in the past month (3.7% vs. 2.4% among those reporting no/low distress).
Among those using medication for weight loss, 15% (about one in seven) were using medication not licensed for this purpose (such as Rybelsus licensed in the UK for type 2 diabetes only).
Using drugs "off-label" can also pose safety risks, the researchers said, if the medicines are accessed without appropriate clinical supervision.
Interest in using drugs to support weight loss in future was reported by 6.5% of respondents who had not used a medication for weight loss in the past year (equivalent to 3.3 million). Interest was higher among women, with nearly one in 10 (8.9%) saying they would be likely or very likely to consider using them in the next year, and among people aged 45 to 55 (9.7%).
By contrast, only one in 20 (5.1%) men said they would likely consider using weight loss medications in the next year.
Interest was also higher among people who had experienced moderate or severe psychological distress in the past month (10.0% vs. 5.2% among those reporting no or low distress).
Jo Harby, Director of Health Information at Cancer Research UK, said: "As obesity rates rise in the UK, this study shows growing public interest in weight loss medication. While these drugs can aid weight loss, they're not a silver-bullet, as evidence suggests most people regain weight after treatment.
"More research is needed on their long-term impact, how these drugs affect cancer risk, and how best to support people to maintain a healthy weight. These drugs should only be prescribed by healthcare professionals alongside continued care and advice on diet and activity. It's also vital that everyone who needs it can access a range of weight-management support.
"The world around us shapes our health, and the UK Government must do more to create healthier environments for all."
* Mounjaro, for instance, typically costs £200 a month so is unaffordable for many.
** All of these medications function as appetite suppressants by mimicking a hormone (GLP-1, or glucagon-like peptide-1) which makes people feel fuller. Mounjaro, in addition, also helps regulate blood sugar levels by mimicking the hormone GIP (glucose-dependent insulinotropic polypeptide).
***These estimates of specific ages are based on modelling drawing on data from participants of all ages.
