New Muscle Pill Could Help Prevent Muscle Loss During Weight Loss
A new experimental pill is showing promising results in the fight against muscle loss, potentially offering a breakthrough for people taking popular GLP-1 weight-loss medications such as Ozempic and Wegovy.
The drug, known as ATR-258, is being developed by biotechnology company Atrogi and is designed to reduce body fat while simultaneously increasing lean muscle mass and improving strength.
According to findings highlighted by Men’s Health, an early human trial conducted through the University of Copenhagen produced encouraging results after just eight weeks of treatment.
The findings come as GLP-1 medications continue to grow in popularity, raising concerns about the amount of muscle people may lose alongside body fat during significant weight loss.
Unlike traditional weight-loss medications that primarily target appetite or metabolism, ATR-258 works directly on skeletal muscle, activating cellular pathways involved in muscle growth and function.
Eight-Week Trial Shows Fat Loss and Muscle Gains
Researchers tested ATR-258 on 13 men classified as overweight or obese. Participants took the experimental pill once daily for eight weeks.
The results showed improvements in body composition and lower-body muscle power.
On average, participants experienced:
- 2.4 pounds (1.1 kg) of body fat lost
- 1.8 pounds (0.8 kg) of lean mass gained
- 13% improvement in lower-body muscle power
- Eight weeks of once-daily treatment
The combination of fat loss and increased lean mass is particularly noteworthy because losing weight often involves reductions in both fat and muscle tissue.
Principal investigator Morten Hostrup admitted that the improvements in lower-body performance exceeded his expectations:
“What struck me most was the magnitude of the signal in lower-extremity power.”
He explained that while researchers understood the potential of the drug’s underlying mechanism to improve muscular performance, the size of the observed improvement was surprising.
The findings have provided researchers with a reason to pursue larger clinical trials to determine whether the results can be replicated.
Could ATR-258 Help People Taking GLP-1 Weight-Loss Drugs?
One of the most intriguing potential applications for ATR-258 involves people taking GLP-1 medications.
Drugs such as Ozempic, Wegovy, and Zepbound have transformed obesity treatment by helping patients achieve substantial weight loss. However, some of that weight loss can come from lean tissue rather than body fat alone.
Preserving muscle is particularly important because skeletal muscle plays a critical role in strength, mobility, metabolic health, and long-term physical function.
This creates an opportunity for treatments that could help patients lose fat while maintaining or potentially increasing muscle mass.
ATR-258 could eventually serve as a complementary treatment alongside GLP-1 medications, although researchers have not yet established whether the drug can prevent muscle loss in patients using those medications.
Importantly, the initial eight-week trial did not demonstrate that ATR-258 works in combination with GLP-1 drugs. That possibility remains a subject for future research.
Researchers See Potential Beyond Weight Loss
The drug’s possible applications extend beyond obesity treatment.
Researchers believe ATR-258 could eventually help address sarcopenia, the age-related loss of muscle mass and strength, as well as certain diseases that cause significant muscle wasting.
Professor Tore Bengtsson, Atrogi’s founder and Chief Scientific Officer, said the early findings support the company’s approach.
“To see fat loss alongside an increase in lean muscle mass and improvement in muscle function represents a truly differentiated profile, and is highly encouraging,” Bengtsson said.
He also emphasized the potential for investigating the treatment in conditions associated with muscle weakness and deterioration.
Despite the encouraging findings, ATR-258 remains an experimental medication. The initial study involved only 13 participants over eight weeks and did not include a placebo control group, making it too early to draw conclusions about long-term effectiveness or safety.
Researchers are expected to begin the next phase of testing in 2027, with larger clinical trials designed to further evaluate the drug’s effectiveness.
