‘I can’t handle this’: Texas runner took pricey GLP-1s while training for a half marathon, only to drop out due to side effects

The difference this time around was that Keri was spending hundreds a month on tirzepatide for weight loss, the active ingredient in Eli Lilly’s Zepbound and Mounjaro, medications approved for weight management and type 2 diabetes.

“After that half marathon, I was so sick,” Keri told The Guardian.

The rise of GLP-1s

According to a 2026 Gallup survey, 11% of American adults reported taking GLP-1 medications for weight loss, up from just 3% in 2024. But as GLP-1 medications become more popular, how do they fit into the lives of people who regularly push their bodies to the limit?

Ashley Koff, a registered dietitian and author of the USA Today bestselling book Your Best Shot, says that while everyone should be moving regularly throughout the day, more demanding physical activity requires a more personalized approach to nutrition.

“What needs to be understood and personalized is that intensity and duration of activity will impact digestion and nutrient needs,” Koff told Moneywise, explaining that it’s even more important for people taking GLP-1 medications, which can affect digestion and change how much, when and what people eat.

For endurance athletes, who rely on adequate nutrition to fuel long runs and recover afterward, those changes can become particularly concerning. Dr. Brandon Richland, a board-certified plastic surgeon practicing in Orange County, California, warns that the appetite-suppressing effects of GLP-1 medications could make it harder for athletes to consume enough calories to meet their body’s needs.

“These medications reduce hunger and an endurance athlete who consumes a significant amount of calories daily can quickly become malnourished,” Dr. Richland told Moneywise. “This increases your risk of losing muscle mass in addition to fat mass.”

Can runners adapt to GLP-1s?

Not every runner taking GLP-1 medications has had the same experience as Keri. For Steve, a 44-year-old runner from Oregon, the first few weeks on compounded tirzepatide were challenging. After starting the medication in July 2026, he noticed that runs he once completed with ease were becoming more difficult, according to The Guardian.

Four weeks into the medication, Steve decided to halve his dose based on advice he'd found on Reddit. He said his training subsequently improved.

“I don’t feel as exhausted any more,” he said.

Although his weight loss has stalled, Steve said being able to keep up with his training mattered more to him than shedding additional pounds. His experience, however, shouldn't be taken as medical advice. Patients should consult their prescribing physician before changing their GLP-1 dosage.

The financial cost of GLP-1s

While research is still developing on how GLP-1 medications affect endurance performance, there’s another major consideration for runners: the cost.

According to Eli Lilly, Zepbound starts at $299 for a 28-day supply of its 2.5-milligram starting dose through its self-pay program. The 5-milligram dose costs $399, while higher doses start at $449 for eligible patients who meet certain requirements, including refilling within 45 days to maintain the discount. Novo Nordisk offers Wegovy injections for $349 per 28-day supply for standard doses.

At $349 to $449 per fill, 12 fills could cost roughly $4,200 to $5,400 out of pocket, enough to cover 48 weeks of treatment. Those figures are illustrative, rather than average patient costs, and don’t include additional medical appointments or testing. Actual expenses depend on the medication, prescribed dose, insurance coverage and eligibility for discounts.