Recent guidelines released this week by the World Health Organization (WHO) endorse the use of popular GLP-1 drugs, including Ozempic, Wegovy, Mounjaro, and Zepbound, as long-term treatments for obesity, a condition affecting more than 1 billion people globally. The recommendations approach as three major reviews commissioned by the WHO highlight both the substantial weight loss potential of these medications and concerns surrounding industry funding of related research.
The reviews, published by Cochrane, analyzed data from trials involving tirzepatide, semaglutide, and liraglutide – all GLP-1 receptor antagonists initially developed to treat type 2 diabetes. Researchers found that each drug led to greater weight loss than a placebo, with tirzepatide demonstrating an average reduction of approximately 16% of body weight after 12 to 18 months. Semaglutide resulted in roughly 11% weight loss over 24 to 68 weeks, even as liraglutide showed more modest results, averaging 4-5% weight loss.
While the weight loss results are promising, the reviews likewise revealed limitations in the existing evidence. Researchers noted a lack of long-term data on health outcomes, potential side effects, and a significant presence of industry funding in many of the trials. “These drugs have the potential to bring about substantial weight loss, particularly in the first year,” said Juan Franco, co-lead researcher from Heinrich Heine University Düsseldorf, Germany. “It’s an exciting moment after decades of unsuccessful attempts to identify effective treatments for people living with obesity.”
The WHO’s decision to add GLP-1 therapies to its Essential Medicines List for managing type 2 diabetes in high-risk groups occurred in September 2025, paving the way for these new obesity treatment guidelines. The agency’s director-general, Dr. Tedros Adhanom Ghebreyesus, emphasized that while medication is not a singular solution, GLP-1 therapies can assist millions in managing obesity and mitigating associated health risks.
However, the reviews underscored concerns about potential conflicts of interest due to the extensive involvement of drug manufacturers in the design, execution, and reporting of many studies. Eva Madrid, co-lead researcher from the Universidad de Valparaíso, Chile, stressed the require for more independent research, stating, “We need more data on the long-term effects and other outcomes related to cardiovascular health… More independent studies from a public health perspective are needed.”
Access to these medications remains a significant barrier. The WHO warned that, even with increased production, fewer than 10% of those who could benefit are projected to have access by 2030. High costs currently limit access to semaglutide and tirzepatide, though the price of liraglutide has decreased with the expiration of its patent and the availability of generic versions. Semaglutide’s patent is also set to expire in 2026.
The reviews also highlighted a lack of representation from diverse global settings, with most trials conducted in middle- and high-income countries. Researchers emphasized the importance of studying the efficacy and safety of these drugs in various populations, given differences in body composition, diet, and health behaviors.
The WHO has issued a global call to its member states to ensure obesity management is universally available, affordable, and sustainable. The findings from these reviews will directly inform the development of comprehensive global guidelines on the use of GLP-1 receptor agonists for obesity treatment, with further research planned to address the identified gaps in evidence.