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The growing popularity of GLP 1 weight loss drugs has opened an unexpected debate in professional sport, with scientists questioning whether medications designed primarily for weight management could eventually influence athletic performance.
The discussion has intensified following Serena Williams' public disclosure that she used tirzepatide after struggling to lose weight following the birth of her child. Williams has described experiencing improvements in areas including her joints, cholesterol and cardiovascular health.
GLP 1 medications work by mimicking hormones involved in appetite regulation and feelings of fullness. Tirzepatide also acts on another hormone known as GIP. The drugs can produce substantial weight loss and have increasingly been prescribed to people with obesity, overweight related health conditions and type 2 diabetes.
For elite athletes, however, weight can have a direct relationship with performance. In sports such as boxing and wrestling, competitors must meet strict weight categories, making any medication capable of reducing body weight potentially significant.
At present, GLP 1 drugs are not prohibited by the World Anti Doping Agency. They are included in WADA's monitoring programme, meaning the organisation is watching their use and potential effects but does not currently classify them as banned performance enhancing substances.
Researchers say one of the biggest problems is the lack of studies involving elite athletes. Scientists therefore cannot yet establish whether the medications provide a meaningful competitive advantage.
There are several possible effects worth examining. GLP 1 drugs may improve metabolic health and reduce inflammation, while research has also linked them with reduced risks of cardiovascular problems. These changes could theoretically benefit some athletes, particularly those who previously had weight related health difficulties.
However, the medications could also create serious disadvantages. One concern is muscle loss during weight reduction. Athletes depend heavily on muscle strength and endurance, meaning losing too much lean mass could undermine performance and increase injury risks.
Another concern is under fuelling. GLP 1 drugs suppress appetite, potentially making it difficult for athletes to consume enough calories to meet the demands of intensive training. Insufficient energy intake can interfere with recovery, training adaptation and performance.
Researchers have therefore cautioned against assuming that weight loss automatically translates into improved athletic ability. An athlete who loses excess body fat while preserving muscle could potentially benefit, but rapid weight loss accompanied by significant muscle loss could have the opposite effect.
The issue is particularly complicated because GLP 1 medications are intended for medical treatment rather than competitive enhancement. Pharmaceutical companies have emphasised that their products should be used according to approved medical indications.
As more athletes and members of the public gain access to these medications, sports authorities are likely to face increasing questions about fairness, health and competitive advantage.
For now, scientists say the evidence remains insufficient to classify GLP 1 drugs as performance enhancing. Until more research is conducted among elite athletes, the debate is likely to continue, leaving sporting organisations to monitor a rapidly changing medical landscape.
