The GLP-1 Debate Hits Pro Sports
On the surface, it's easy to make the hypothesis that a GLP-1 could potentially make someone better at their sport. If an athlete becomes lighter, can't they move around the court faster? Could changes in body composition improve agility or endurance? Could the drugs be seen as a competitive advantage? Well, it's a bit more nuanced than you think. As the ecosystem around these medications begins to change and pro athletes open up about using them, the world of sports has to figure out how to answer those questions.
The debate has already spilled into tennis culture. During the Cincinnati Open in August, a Ro banner depicting Serena Williams injecting a GLP-1 medication flew above the tournament grounds. The 23-time Grand Slam title holder has become a particularly potent symbol in this conversation, publicly disclosing her GLP-1 use in 2025 and has since returned to competitive tennis, prompting some online commenters to question the overlap among her body transformation, commercial partnership, and athletic comeback. But those questions are not evidence that the medication improved her performance, which is precisely the distinction the World Anti-Doping Agency (WADA) and researchers are still trying to understand.
A newly published study surveyed sports physicians about their experiences with GLP-1 medications in competitive sports. Of the physicians who responded, 12 percent reported being aware of athletes who had used GLP-1 drugs without medical need, while 13 percent said athletes had approached them about using or prescribing the medications. Those numbers do not mean that 12 percent of athletes are using GLP-1s though. The study surveyed physicians, not athletes, and cannot establish the prevalence of GLP-1 use across professional sports. But it does suggest that sports-medicine professionals are already encountering the issue.
Daniel Read, PhD, a researcher at the University of Hertfordshire and an author of the study, says the interest physicians encountered appeared to have several motivations, including performance enhancement, body image, and legitimate medical need. So what's being done to monitor the usage and what type of advantages, if any, can GLP-1s offer in the world of sports?
How Are GLP-1s in Sports Currently Being Monitored?
Right now, semaglutide and tirzepatide are included in the World Anti-Doping Agency's 's Monitoring Program, which tracks substances that aren't prohibited, but that the agency wants to monitor for potential patterns of misuse. WADA spokesperson Andrew Maggio confirmed that athletes are tested for the medications as part of regular doping-control analysis so the agency can gather information about how prevalent their use is in sports.
"Since semaglutide and tirzepatide are not prohibited, if found in a sample, it is not reported as a positive test (adverse analytical finding), so there are no consequences for the athlete if found," Maggio says. "It is reported as part of the Monitoring Program." He added that data from the Monitoring Program are reviewed by WADA's List Expert Advisory Group "before any decision to include or not on the list of prohibited substances and methods is made."
Could a GLP-1 Actually Make Someone Better at Their Sport?
As pro athletes enter the GLP-1 conversation, questions about whether the drugs could function as "performance enhancers" are entering sports, too. But experts say the hypothesis is far more complicated than lighter equals faster. In tennis, for example, players need explosive movement to reach a drop shot, strength to generate power from the baseline, and enough endurance to repeat those movements over matches that can last for hours. Then, they need to recover and do it again. Weight loss alone doesn't guarantee any of those things.
"Weight loss and performance enhancement are not the same thing," says Alexandra Sowa, MD, an obesity medicine physician and author of "The Ozempic Revolution." According to Dr. Sowa: "Right now, we don't have clinical evidence showing that GLP-1 medications enhance elite athletic performance."
For an athlete who has obesity, Dr. Sowa says losing excess weight could improve mobility or metabolic health. But that is different from demonstrating that the medication itself enhances athletic performance. In fact, some of the same mechanisms that make GLP-1 medications effective could potentially create challenges for an elite athlete. "These medications suppress appetite, so if an athlete isn't intentional about fueling, it can become very easy to under-eat relative to an enormous training load," Dr. Sowa says. That could be particularly relevant in tennis.
"You can have an athlete competing for hours in extreme heat," Dr. Sowa says. "If the medication is suppressing appetite, they're not fueling enough, they're drinking less, or they're having nausea or GI symptoms, now you have to think about dehydration and inadequate energy availability on top of that." Her conclusion is simple: "A lower number on the scale does not automatically mean better performance."
On top of that, significant weight loss can include reductions in both fat mass and lean mass. That distinction could matter much more for an elite athlete than the number on the scale. "Whenever we lose a significant amount of weight, we lose some lean mass along with fat," Dr. Sowa says. For an athlete whose livelihood depends on strength and power, the more useful questions would be: What happened to body composition? Did the athlete maintain strength? Were they consuming enough protein and total calories? And how were they recovering? "Those are much more meaningful endpoints," Dr. Sowa says.
Ultimately, researchers don't yet have the athlete-specific evidence necessary to know how those competing effects ultimately translate to elite performance. "At present, there is no evidence from research with elite athletes comparable to the quality of athletes competing at an elite level to state whether weight loss medications provide any competitive advantage or disadvantage," Dr. Read tells Popsugar. There are plausible arguments in both directions.
So what evidence would be needed before researchers could credibly call these medications performance enhancing? Ideally, he says, that evidence would come from randomized, double-blind, placebo-controlled trials comparing athletes who use GLP-1 medications with those who don't, Dr. Read says. Even then, researchers would have to decide what "performance" means. In an endurance sport, for example, researchers might have an objective measurement like time, while in a sport with an aesthetic or judged component — or one where reduced mass may be advantageous — the effects could be more subjective.
But What If the Athlete Has Obesity?
This is where the GLP-1 debate becomes even more complicated. Athletes receive medical treatment all the time. They use corrective lenses, physical therapy, surgery, and prescription medications to treat conditions that could otherwise interfere with their ability to compete. So what happens when the condition being treated is obesity?
"One thing that gets lost in these conversations is that obesity is a chronic metabolic disease," Dr. Sowa says. "In someone who has obesity, we're not just using a medication to make them thinner. We're treating biological pathways that regulate hunger, satiety, food intake, and energy balance."
Being an elite athlete doesn't necessarily remove someone from that patient population. "Elite athletes can have excess body fat and metabolic dysfunction, too," Dr. Sowa says. If an athlete has a clinical indication for a GLP-1, being a professional athlete "doesn't somehow make that diagnosis less legitimate," she says. And that needs to be distinguished from an already-lean athlete taking the medication specifically to drive their weight or body fat lower.
"My biggest concern is that we don't conflate potential misuse with legitimate obesity treatment," Dr. Sowa says. "WADA monitoring semaglutide and tirzepatide is not the same as saying these medications are prohibited or that they've been proven to enhance performance." She sees investigating potential misuse as legitimate, particularly when medications are being used by already-lean athletes without a medical indication.
"But we should be able to have that conversation without implying that an athlete who is appropriately treating obesity is somehow cheating," Dr. Sowa says. "Those are two very different things." Where does treatment end and enhancement begin? That may ultimately become the larger question for professional sports. Correcting someone's vision can improve athletic performance. Treating asthma can allow an athlete to breathe normally. Rehabilitation after an injury can restore an athlete's ability to compete. In other words, medical treatment and improved performance aren't mutually exclusive.
Anti-doping policy therefore has to wrestle with more than whether an intervention changes someone's physical capabilities. For Dr. Read, GLP-1s are bringing renewed attention to a tension that already exists in professional sports. "The line between enhancement and health has always been difficult to define," he says.
For now, WADA is continuing to gather information, rather than drawing a line. "The WADA Executive Committee has decided not to change the status of GLP-1 receptor agonists for the coming year, 2027," Maggio said. "As such, it will remain on the Monitoring Program." What remains unanswered is what that monitoring will ultimately show — and whether future evidence will change how anti-doping authorities view the medications. For now, perhaps the most important thing spectators can do is recognize the difference between a body changing and a rule being broken.
CeCe Olisa is a trailblazing voice in inclusive health and beauty, dedicated to inspiring women to embrace self-care with confidence. As a certified fitness instructor and founder of Cocoa by CeCe, she blends personal experience with expert insight to make health and beauty joyful, accessible, and empowering. Each week in her CeCe Olisa Newsletter, she shares unfiltered stories, tools, and resources to help women build confidence from the inside out. Through everything she creates, she's redefining beauty and fitness with self-love, self-care, and self-confidence at the center.
