The World Anti-Doping Agency (WADA) continues to closely monitor Glucagon-like Peptide-1 (GLP-1) receptor agonists, widely known as weight-loss and diabetes medications, as tennis legend Serena Williams makes a high-profile return to competitive play while openly using and promoting these drugs. GLP-1s are currently permitted in sports but remain under scrutiny for their potential impact on athletic performance and health. WADA initiated its monitoring program for semaglutide in 2024 and tirzepatide in 2025, with a decision on potential prohibition anticipated before the 2028 Los Angeles Olympics.
WADA's monitoring program tracks substances not yet on the prohibited list to detect patterns of misuse that could enhance performance, pose health risks, or violate the spirit of sport. According to a WADA spokesperson, "The monitoring program includes substances which are not on the Prohibited List, but that WADA wishes to monitor in order to detect potential patterns of misuse in sport." While GLP-1s can lead to significant weight loss, some experts raise concerns about potential loss of lean muscle mass, which could negatively impact an athlete's speed, endurance, and explosiveness.
Serena Williams, a 23-time Grand Slam champion, has become a prominent figure in the discussion, having openly used GLP-1 medications for weight loss and serving as a "celebrity patient-ambassador" for telehealth company Ro. Williams stated in an interview on NBC's Today show, "As an athlete and as someone that has done everything, I just couldn’t get my weight to where I needed to be at a healthy place, and believe me I don’t take shortcuts." Her return to the WTA Tour at events like the HSBC Championships has intensified the conversation around GLP-1 use in elite athletics.
The debate surrounding GLP-1s in sports centers on whether their weight-reducing effects confer an unfair advantage, particularly in weight-sensitive disciplines. While some argue that rapid weight loss could improve power-to-weight ratios, others highlight the potential for adverse effects like muscle wasting and gastrointestinal issues. Industry observers also note that companies often align with high-profile athletes like Williams to enhance the visibility and acceptance of GLP-1 medications, contributing to their growing mainstream use despite ongoing ethical and health discussions.
