Last year, Serena Williams announced a partnership with Ro, a GLP-1 medication. Ro’s claim to fame is that it’s not specifically engineered as a diabetes medication, and usage is encouraged purely for weight loss. Serena’s husband Alexis Ohanian invested in Ro, and Serena stars in Ro’s commercials and print ads. She’s given several interviews saying flat-out that she began researching GLP-1s after she struggled to lose weight after the births of her daughters. Ro worked for Serena – she’s lost a lot of weight and she looks fit and like she’s back to her pre-baby body. Serena came back to the tennis tour this week, and she says she’s only back to play doubles and have a good time. I watched her first match back and while there’s still some rust, Serena looks pretty sharp. Her perfect serve is still there, her power is still there, and she still has pretty good instincts at the net. Well, now is apparently the time where the sports world wrings their hands over whether GLPs should be categorized as performance-enhancing. Can these men just let Serena breathe for one week???

No one expects [Serena Williams’] comeback to stop at Queen’s, or with doubles, though she has not directly committed to playing singles yet. Immediately, Williams reclaimed her position as the most magnetic star in the sport. She also became by far the most prominent athlete to compete at the highest level of their sport having taken GLP-1 drugs, which anti-doping authorities have been monitoring since 2024.

They are not a prohibited substance, nor classed as a performance-enhancing drug. They may never be. Williams’ communication team declined an interview for this story, and to express her views on the debate about whether the drugs could be banned.

Semaglutides and tirzepatides, the two main classes of GLP-1 drug, have been on the World Anti-Doping Agency (WADA) monitoring program since 2024. They work by mimicking the behavior of glucagon, a naturally occurring hormone that triggers the pancreas to release insulin, slow digestion and reduce appetite and hunger. People who take GLP-1s — Glucagon-Like Peptides — report significant reduction in “food noise,” the part of their mind that thinks about the next snack or meal. The reduction in food intake can lead to significant weight loss.

There is no timetable on the WADA process for establishing whether GLP-1s are performance-enhancing, a spokesperson for the organization said. Tennis anti-doping protocol is managed by the International Tennis Integrity Agency (ITIA), but as an Olympic sport, WADA oversees its compliance with its code.

“The WADA List Expert Advisory Group has discussed their status, as well as other substances of the same class,” the statement said. “Semaglutide and tirzepatide were added to the Monitoring Program to track patterns of use in sports in and out of competition. 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.”

A spokesperson for Novo Nordisk said in a statement that the pharmaceutical company, which produces and distributes GLP-1s, agreed with WADA’s decision to monitor GLP-1 usage: “We are supportive of the WADA recommendation, and we strongly discourage use/promotion outside the indicated population and approved label.”

To land on the banned list, a substance has to satisfy two of three criteria: The potential to enhance sport performance; the potential to be a risk to athletes’ health; the potential to violate what WADA defines in its code as the “spirit of sport.” There is a divide in the anti-doping world over whether violating the “spirit of sport” is too vague a criterion, and that enforcement should be based on science alone. For now, though, taking what WADA deems a shortcut in training can contribute to a substance landing on the banned list. It has shown increasing concern about the role of weight-loss drugs in sports. Minutes of a meeting of WADA’s Health and Research Committee last August show a discussion of “whether a new class addressing all types of weight management substances should be created, not only for weight category sports but also weight-sensitive ones (e.g. gymnastics, figure skating, cycling).”

How GLP-1s cause weight loss may further complicate whether they can be considered performance-enhancing. Fat loss is the main contributor. But studies of GLP-1 patients have shown that muscle loss also occurs, which for athletes, would do the opposite of enhancing performance.

[From The NY Times]

Further down in the article, they mention the very obvious work-around for tennis players, which is a Therapeutic Use Exemption (TUE) – basically, if you can provide a doctor’s note for why you need to be on a certain drug, you’re basically allowed to take it. While Serena’s use of Ro has always been specifically for weight loss (in her own words), I think it would be pretty easy for Serena or anyone else to find a doctor saying that a GLP-1 is medically necessary for so-and-so. While it feels like they’re picking on Serena, I actually do think this is a larger issue which WADA will need to reckon with. The most interesting part is where people could argue against the performance enhancement aspect because GLPs lead to muscle loss. I would also argue that there’s anecdotal evidence that GLPs might negatively affect an athlete’s competitive drive – GLPs have been shown to suppress all cravings, not just for food, but also for dopamine. What if GLPs suppress the wacky brain chemistry which elite athletes need to train and compete at such high levels?

Photos courtesy of Backgrid, Cover Images.