Summary of GLP-1 risk to athletes
- Serena Williams recently announced that she takes GLP-1 weight-loss drugs
- GLP-1 drugs suppress appetite and risk inadequate nutrient intake
- Athletes need to consume higher-than-average carbs and protein for energy, repair and recovery
- By suppressing appetite, GLP-1s can prevent athletes from getting the nutrients they need
- This can lead to muscle loss and low energy, and even affect performance
Last month, US tennis megastar Serena Williams made public that she had been using GLP-1 weight loss drugs. Revealed while she was promoting the drugs as part of a partnership with telehealth company Ro, the former athlete says the drugs helped her lose weight following pregnancy.
Even for ordinary consumers, it is important to pay attention to nutrient intake on GLP-1s, as taking the drugs often means they eat less food. For athletes, the importance of this is even more significant.
What are the unique nutritional needs for athletes?
Athletes have different nutritional needs to the average person, and must adjust their diets accordingly.
Factors such as carbohydrate intake and total energy demand are different for athletes, explains nutritionist and British Dietetic Association (BDA) spokesperson Claire Fudge.
During training, “adequate intake of carbohydrates and protein is essential to support glycogen storage, muscle repair, and exercise adaptation. However the exact needs, volumes and timing will vary”.
The area of protein intake for athletes is hotly debated, but current estimates suggest 1.2–2.2 grams per kg per day to support muscle maintenance and immune function.
Most athletes have more than adequate protein intakes, Fudge explains.
Does GLP-1 use pose a risk for athletes?
GLP-1 intake can pose a risk for athletes, Fudge suggests. And it’s not a theoretical issue – she has seen some athletes taking the drugs for weight loss, despite their already active lifestyle.
“While [GLP-1s support] weight loss in the general population, [they present] clear risks for athletes, who need to fuel pre, sometimes during, and post-training to meet energy and recovery needs, when not hungry or who physically can’t eat any more.”
Furthermore, Fudge questions whether athletes’ diets could become unbalanced due to the drugs, leading them to become low in micronutrients needed for recovery and repair.
“With GLP-1 use, I’ve seen athletes unable to finish meals, especially those high in carbohydrates, fibre, or protein, which are critical to glycogen storage and muscle preservation.
“This means the diet starts to become imbalanced when they may try to take on adequate portions for carbohydrates and protein, at the risk of then not eating vegetables or salad and the higher fibre foods full of antioxidants and phytonutrients due to being too full.”
Could it affect athletic performance?
Using GLP-1 drugs poses a risk to athletic performance as well as health.
While producers of the drugs are working to solve the issue, currently GLP-1s can lead to muscle loss as well as fat loss. In fact, estimates suggest that 40% of the weight lost due to GLP-1s is in fact lean mass.
The drugs “could potentially reduce power and explosiveness in power sports whilst in endurance sports during long training, it means slow gastric emptying so athletes may not be able to fuel during sessions,” explains Fudge.
Even if the athletes were to stop using the drugs before a competition, the effects could linger for around seven days.
When the body doesn’t have enough energy to meet the needs of both training and the day’s other activities, it may begin to break down muscle tissue to release amino acids for immune function, wound healing and gluconeogenesis (when the body creates new glucose molecules). This has the potential to be damaging during heavy training phases or post-race recovery (when protein needs are elevated but appetite suppressed).
This could affect training itself, reducing strength gains or increasing fatigue.
In the long-term this could even cause LEA (Low Energy Availability), which in itself can lead to REDs (Relative Energy Deficiency in Sport), she suggests, if energy and fuelling for training is not met.
This has long-term implications for bone health, hormonal balance, and of course, performance.
