Lighter but weaker? The hidden costs of Ozempic and weight-loss drugs for endurance athletes
Why the popular semaglutide drugs may hurt your performance more than help it

Ozempic and other semaglutide medications have skyrocketed in popularity as weight-loss aids, with prescriptions surging by over 300% in the past year alone. Developed as a treatment for managing Type 2 diabetes, these medications have become household names in health and wellness circles as well. You may even know someone who's currently taking it—whether it's to control their blood sugar, shed a few pounds before their wedding or help slim down before the racing season.
Ozempic (semaglutide) is part of a class of medications known as GLP-1 receptor agonists, which were developed to help manage blood glucose levels in people with diabetes. Ozempic received FDA approval in 2017 and has since surged in popularity due to its weight-loss benefits, even among non-diabetic individuals. Ozempic works by mimicking the GLP-1 hormone, which regulates appetite. It suppresses appetite, slows gastric emptying and promotes feelings of fullness, often leading to reduced calorie consumption. When a person burns more calories than they consume, they are in a calorie deficit, which results in weight loss.
While these medications offer substantial health benefits for those who truly need them—such as managing Type 2 Diabetes or achieving significant weight loss when other methods have failed—their widespread adoption, now extending into endurance sports communities, raises an important question: are they safe for active individuals? Can Ozempic be a tool to help you achieve or maintain race weight?
Not all weight loss is the same
When we turn our focus to endurance athletes—such as long-distance runners, cyclists and triathletes—we know that high levels of energy are essential to compete and perform optimally. Achieving this depends heavily on proper nutrition, combined with muscular endurance, consistent training and adequate recovery.
Dr. Xavier Collazo, a DPT specialising in sports performance and rehabilitation at Tampa Bay Performance Physical Therapy, emphasises that the benefits of GLP-1 drugs must be carefully balanced against the potential risks, particularly for non-obese and non-diabetic athletes.
“While these effects can be beneficial to those dealing with high BMIs or obesity, the endurance athlete, who requires large energy sources to perform and compete, will typically find that these effects would decrease performance to a degree,” he says.
“Not to mention the fact that when you lose weight, you do lose muscle, which is the driving force of all our movement."
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In cycling, it’s long been believed that losing weight improves one's power-to-weight ratio a.k.a watts per kilogram. Thus, GLP-1 medications may seem like an appealing tool at first glance. However, these medications can potentially cause more lean muscle loss than traditional weight loss methods, potentially because weight loss is so rapid. The data is slim but some early research suggests that while GLP-1s undoubtedly aid in weight loss, they could do so at the expense of lean muscle mass. As a result, while the number on the scale might go down, your power output may decline alongside it.
The Risk of Under-fueling
Nutrition is a cornerstone of both performance and recovery. Protein is essential for muscle repair and growth, carbohydrates fuel energy needs, and healthy fats support brain function. With suppressed appetite comes the risk of under-fueling and potentially disrupting the body’s recovery processes, ultimately leading to a decline in performance.
Cycling demands a high caloric intake to sustain intense training and support recovery. The concern with Ozempic lies in its potent appetite-suppressing effects, which could cause one to unintentionally underfuel. This reduction of caloric intake can hinder the recovery process and increase the risk of overtraining and injury.
TBD
As GLP-1 medications become more widely used, research on their long-term effects for non-diabetic users is still in its early stages. With mass production and distribution relatively recent, there is much we have yet to understand about their broader implications.
“For now, in my personal opinion, I’d advise athletes to stick to more conventional methods of weight loss, working with nutritionists, dieticians, or simply structuring their training and intake better,” says Collazo.
Clinical trials are underway to determine if GLP-1 medications do indeed prioritise lean muscle mass over fat loss—and, if so, what can be done to mitigate muscle loss for those who need these medications. For individuals with diabetes or obesity who are benefiting from GLP-1s, increasing protein intake and incorporating strength training during rapid weight loss can help preserve muscle mass.
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