Serena Williams has returned to professional tennis, winning her opening doubles match at the Queen’s Club grass-court tournament alongside Victoria Mboko. The 23-time Grand Slam champion, who previously announced she was using the GLP-1 drug Zepbound for weight management, is now at the center of a growing international debate regarding the intersection of medical weight-loss treatments and athletic competition. Her appearance marks the most high-profile instance of an elite athlete competing while utilizing a medication currently under observation by the World Anti-Doping Agency (WADA).
Why is WADA monitoring weight-loss drugs?
WADA added semaglutides and tirzepatides—the core components of drugs like Zepbound—to its Monitoring Program in 2024 to track potential patterns of misuse in sports. According to a WADA spokesperson, the agency intends to determine if these substances offer a competitive edge or violate the “spirit of sport.” While not currently prohibited, the drugs work by mimicking hormones that slow digestion and suppress appetite, leading to significant weight loss. WADA’s Health and Research Committee has specifically discussed creating a new category for weight-management substances, particularly for sports where weight classes or body composition are critical, such as cycling, gymnastics, and figure skating.

To be added to the WADA Prohibited List, a substance must meet two of three criteria: the potential to enhance performance, a risk to athlete health, or a violation of the “spirit of sport.”
How do GLP-1 medications affect athletic performance?
The impact of GLP-1 drugs on elite performance remains a subject of scientific and regulatory contention. While these drugs effectively reduce body fat, studies have shown they can also contribute to muscle mass loss. According to Matthew Fedoruk, chief science officer at the U.S. Anti-Doping Agency (USADA), manufacturers are likely to refine these drugs to minimize side effects, which could eventually make them more advantageous for athletes. Mitchell Steiner, CEO of the pharmaceutical company VERU, noted that the industry is already exploring “adjunctive therapies” to prevent muscle-wasting, though such combinations—like the banned substance Ostarine—are strictly prohibited in competition.
What does Serena Williams’ return mean for the sport?
Williams’ comeback at the Queen’s Club has elevated the visibility of GLP-1 usage in professional athletics. The 44-year-old athlete, who serves as a paid ambassador for the telehealth company Ro, stated on Oprah Winfrey’s podcast that she turned to medication after traditional training methods failed to address weight challenges following her two pregnancies. Her husband, Alexis Ohanian, is a significant investor in Ro. While Williams has not committed to a full singles return, her presence on the court forces tennis governing bodies—including the International Tennis Integrity Agency (ITIA)—to address the evolving landscape of sports medicine and the definition of a “shortcut” in elite training.

| Substance Class | Current Status | Primary Regulatory Concern |
|---|---|---|
| GLP-1s (Zepbound/Wegovy) | WADA Monitoring Program | Potential “shortcut” vs. medical necessity |
| Diuretics | Prohibited List | Masking agent for other drugs |
Frequently Asked Questions
Are GLP-1 drugs currently banned in tennis?
No. Semaglutides and tirzepatides are not prohibited substances under current WADA or ITIA regulations. They are only being monitored to track usage patterns.
Can athletes receive an exemption for these drugs?
If the drugs are eventually prohibited, athletes could apply for a Therapeutic Use Exemption (TUE). According to established protocols, these are granted for legitimate medical conditions, such as diabetes, provided the substance does not offer a performance-enhancing advantage.
What is the primary health concern for athletes using these drugs?
The main concern for athletic performance is the loss of lean muscle mass, which often accompanies the weight loss induced by GLP-1 medications.
Keep an eye on WADA’s annual updates to their Prohibited List. As clinical data on muscle-sparing GLP-1 formulations emerges, the regulatory stance on these medications may shift rapidly.
What are your thoughts on the use of modern medical treatments in professional sports? Join the conversation in the comments below or subscribe to our newsletter for updates on the intersection of health and high-performance athletics.

















