New GLP-1 Combination Therapy Boosts Weight Loss and Preserves Muscle Mass
GLP-1 drugs like semaglutide (Ozempic and Wegovy) have become a significant advancement in sustainable weight loss for individuals with obesity. Research suggests that combining GLP-1s with muscle-building drugs may further enhance treatment outcomes.
Semaglutide and Bimagrumab: A Promising Combination
Researchers at Eli Lilly and others recently published results from a phase 2 trial investigating the combination of semaglutide with bimagrumab, an experimental antibody designed to prevent muscle loss. The study, published in Nature Medicine, found that individuals receiving the combination therapy experienced significantly greater weight and fat loss while maintaining more lean body mass compared to those taking semaglutide alone.
How the Combination Works
When people lose weight, they typically lose both fat and lean body mass, including muscle. While weight loss generally improves physical function, some studies suggest that GLP-1 medications might lead to slightly more lean body mass loss than usual. Bimagrumab works by inhibiting activin receptor type-2B, a protein that limits muscle growth, potentially counteracting this effect.
Trial Results: Significant Improvements in Weight Loss and Body Composition
The trial involved approximately 500 people with obesity. Over 48 weeks, participants on the highest dose of semaglutide and bimagrumab lost up to 20% of their body weight, while those on the highest dose of semaglutide alone lost up to 15%. By week 72, the combination group also demonstrated a proportionally greater decrease in fat (45.7%) compared to the semaglutide-only group (27.8%), and experienced less lean body mass loss (2.9% from baseline vs 7.4%).
Safety and Tolerability
The combination therapy appeared to be generally safe and well-tolerated, with a safety profile consistent with what is already known about both drug classes. Common side effects included gastrointestinal symptoms associated with semaglutide and muscle cramps linked to bimagrumab.
Future Directions and Potential Benefits
While more research is needed, this combination therapy could be particularly beneficial for individuals at higher risk of muscle loss while taking GLP-1s, such as older adults. Eli Lilly is currently conducting a phase 2 trial combining bimagrumab with tirzepatide (Zepbound and Mounjaro), another obesity medication generally considered more effective than semaglutide. Other companies are also exploring similar combination treatments, suggesting a potential new approach to weight loss is on the horizon.
Maintaining Muscle Mass During Weight Loss: Beyond Combination Therapies
It’s important to note that resistance training and increased protein intake are proven methods for maintaining muscle mass during weight loss, even without the employ of experimental antibodies.
This research signals a potential evolution in weight loss strategies, offering hope for more effective and comprehensive treatments in the future.