The World Health Organization has issued its first global guideline on using GLP-1 medicines to treat obesity, describing them as an effective option but recommending them conditionally because key long-term questions and access barriers remain. The guidance positions GLP-1 therapies as one part of lifelong, comprehensive obesity care that also includes healthy diets, physical activity, and support from health professionals.
WHO’s announcement frames obesity as a major global health challenge affecting more than 1 billion people, and says obesity was associated with 3.7 million deaths worldwide in 2024. Without decisive action, WHO says the number of people living with obesity is projected to double by 2030.
What WHO recommends
WHO’s guideline includes two key conditional recommendations for adults living with obesity. First, GLP-1 therapies may be used for the long-term treatment of obesity in adults, but the guidance excludes pregnant women.
WHO says the recommendation is conditional even though evidence shows these medicines are effective for obesity and can improve metabolic and other outcomes. The organization cites limited data on long-term efficacy and safety, uncertainty about maintenance and discontinuation, current costs, gaps in health-system preparedness, and possible equity impacts as reasons for caution.
Second, WHO says intensive behavioural interventions—structured support focused on healthy diet and physical activity—may be offered to adults with obesity who are prescribed GLP-1 therapies. WHO notes this is based on low-certainty evidence suggesting behavioural support may improve outcomes.
How GLP-1 drugs work—and who they’re for
In a WHO questions-and-answers page, GLP-1 therapies are described as medicines that mimic a natural hormone involved in regulating blood sugar and appetite. WHO says they were first used for type 2 diabetes, and are now also approved for obesity and weight loss.
WHO explains that these medicines stimulate insulin release when blood sugar is high and reduce glucagon secretion, which helps lower blood glucose levels. The agency also says GLP-1 therapies slow digestion and increase feelings of fullness, which can reduce food intake.
WHO stresses that GLP-1 therapies are not appropriate for everyone and should be prescribed by a medical practitioner after considering a person’s health history and clinical indications. Under current WHO recommendations, the medicines may be used as a long-term option for adults with obesity defined as a body mass index of 30 or higher, while the guideline does not cover pregnant women because these drugs have not been tested in that population.
Benefits seen in major reviews
Three Cochrane reviews commissioned by WHO found that GLP-1 receptor agonists produced clinically meaningful weight loss compared with placebo, while also highlighting that evidence on longer-term outcomes and side effects remains limited or uncertain. Across the reviews, tirzepatide, semaglutide, and liraglutide each led to significant weight loss after one to two years, and the effect was likely to continue while treatment continued.
In the Cochrane findings, tirzepatide given once weekly was associated with about a 16% weight reduction after 12 to 18 months, and evidence from eight randomized controlled trials involving 6,361 participants suggested effects could be maintained for up to 3.5 years, although long-term safety data were limited. Semaglutide, also injected weekly, was linked to around an 11% body-weight reduction after 24 to 68 weeks across 18 trials with 27,949 participants, and it increased the likelihood of achieving at least 5% weight loss but was associated with higher rates of mild-to-moderate gastrointestinal side effects. Liraglutide, a daily injection, showed a smaller average weight reduction of about 4–5% across 24 trials with 9,937 participants, and evidence beyond two years was more limited.
The Cochrane summary also reports little to no difference versus placebo for major cardiovascular events, quality of life, or mortality across the reviews, while noting that nausea and other digestive symptoms were more common and some participants stopped treatment because of side effects. “These drugs have the potential to bring about substantial weight loss, particularly in the first year,” said Juan Franco, a co-lead researcher, in comments included with the Cochrane release.
Safety questions, access gaps, and system readiness
WHO’s Q&A lists common side effects as nausea, vomiting, constipation, and diarrhoea, and says these are usually mild and may stop after discontinuation or lessen over time. WHO adds that other gastrointestinal problems—including biliary disease, acute pancreatitis, bowel obstruction, and gastroparesis—continue to be linked to GLP-1 use but are still being evaluated, while thyroid cancer has been cited as a possible harm with risk in humans still under investigation.
WHO says GLP-1 therapies are generally used long term, meaning six months or longer, and that it is monitoring data on long-term efficacy and safety as well as the timing and effects of stopping treatment. The agency also says availability is uneven, with access influenced by production capacity, country registration, cost, and supply issues, and that availability is highest in high-income countries while being much lower in low- and middle-income countries.
In its guideline announcement, WHO warns that without deliberate policies, access could worsen existing health disparities, and it calls for action on manufacturing, affordability, and health-system readiness. WHO also says that even with rapid expansion in production, GLP-1 therapies are projected to reach fewer than 10% of people who could benefit by 2030, and it points to options such as pooled procurement, tiered pricing, and voluntary licensing to expand access.
WHO also notes that global demand has contributed to falsified and substandard products, and says quality and safety depend on regulated distribution, prescribing by qualified health care providers, strong oversight, patient education, and global cooperation.
