Shop SoWell GLP-1 Support

Bimagrumab: A Potential Muscle Protector for People on GLP-1s

Jennifer Hardy
May 31
4 min read

GLP-1 medications like semaglutide and tirzepatide have reshaped the way we talk about weight loss. People who’ve struggled for years are finally seeing results, but the risk of losing muscle mass is real. Could bimagrumab be the medication that solves this GLP-1 challenge?

It's not just a cosmetic issue. Muscle supports strength, mobility, metabolism, and long-term health. Bimagrumab is quietly gaining attention in the research world for its ability to promote muscle growth and reduce fat, even without cutting calories.

While bimagrumab isn’t a next-gen GLP-1, combining the two could someday support greater fat loss and improved muscle preservation. That could benefit people who can’t follow a rigorous workout routine, but it’s not a magic fix. Exercise will still matter in any healthy lifestyle.

Let's learn more about how bimagrumab works.

What Bimagrumab Actually Does

Bimagrumab isn’t a weight loss drug in the traditional sense. It doesn’t suppress appetite or change how your body handles glucose. Instead, it targets something called the activin type II receptor (ActRII). This receptor responds to proteins like myostatin and activin A, which tell your body to stop building muscle.

Bimagrumab blocks that signal. The result? Your body is more open to building or maintaining muscle even during a calorie deficit. In clinical studies, people on bimagrumab experienced increases in lean mass and reductions in fat mass, even without dieting or exercise changes.

That’s the part that makes headlines, but also the part that needs context.

Why Bimagrumab Is Being Developed

Bimagrumab wasn’t created with GLP-1s in mind. It’s being developed to address conditions where muscle wasting or low muscle mass is a core problem. This includes sarcopenia (age-related muscle loss), cachexia (muscle wasting often tied to cancer or chronic illness), and certain metabolic disorders where improving body composition could help with mobility, strength, and insulin sensitivity.

In these contexts, bimagrumab’s role is to help build or preserve skeletal muscle and reduce excess fat, without relying on lifestyle changes alone. That makes it a potential therapy for people who physically can’t exercise due to illness or disability, or whose muscle loss is driven by inflammatory or hormonal processes that override diet and movement.

Now, researchers are exploring how that same mechanism could benefit people using GLP-1s, many of whom are losing muscle during rapid weight loss.

Why It’s Not a Magic Muscle Drug

Our editorial team debated whether to cover bimagrumab at all. It’s easy to see how the headlines could get distorted: "Lose weight and gain muscle without trying!" That kind of spin not only oversells the science, it also risks feeding into disordered eating mindsets or reinforcing the false idea that working out is optional for long-term health.

Yes, early data shows bimagrumab can reduce fat and increase lean mass, even without major diet or exercise changes. But that doesn’t mean you’ll wake up with toned muscles after a few infusions. What it offers is physiological support, not a free pass.

Muscle doesn’t grow on its own. Your body still needs quality protein, strength-based movement, and sleep to stimulate and maintain muscle tissue. What bimagrumab can do is blunt the muscle loss that often happens during calorie restriction, illness, or age-related decline.

It shifts the biology slightly in your favor, especially if you’re struggling to keep up with physical demands or food intake. It might also offer a new approach for those who hit a plateau, where the scale stalls and muscle preservation becomes just as important as fat loss.

So, no—it’s not a shortcut. But it could be a useful tool in the larger equation of health.

The GLP-1 Connection to Bimagrumab

GLP-1 receptor agonists work by reducing appetite, delaying gastric emptying, and improving insulin sensitivity. That usually leads to a major reduction in calorie intake, which translates to weight loss.

But along with fat, people often lose muscle. That’s because a lower-calorie diet can slow protein synthesis and increase muscle breakdown.

This is where bimagrumab could shine. Combining a GLP-1 drug with bimagrumab could mean fat loss from one angle and muscle protection from another. Instead of the typical pattern, lose 30 pounds, and 7 to 10 of those are muscle, you might lose more fat and preserve or even gain lean mass. That could help with metabolism, energy, and function, especially over the long haul.

In preclinical trials, this combo led to more fat loss and better metabolic markers compared to GLP-1 use alone. In human studies, early results are encouraging, too. One trial showed participants gained muscle and lost fat simultaneously, even with type 2 diabetes in the mix.

Who Might Benefit Most

This isn’t something that will be rolled out to everyone casually. If approved, bimagrumab would likely be reserved for people at higher risk of losing too much muscle:

Older adults, where muscle loss can lead to frailty, falls, or functional decline
People with very low starting muscle mass, where further loss could affect mobility or metabolic health
Those on long-term GLP-1 therapy, especially at higher doses or lower food intake

That said, bimagrumab could also have a role in post-weight-loss maintenance. Muscle is metabolically active, which means having more of it can help maintain your resting energy expenditure and fight off rebound weight gain. Preserving muscle could be a key factor in keeping weight off long-term.

What’s Next for Bimagrumab?

Bimagrumab is still in development, with multiple clinical trials underway to test its safety and effectiveness in people with obesity, including those using semaglutide and tirzepatide. Some studies are still enrolling participants, with more data expected by the end of 2025.

That trial will be key in determining how effective and safe the combo really is in humans over a longer term.

If results continue to be positive, future steps may include:

Pushing toward FDA approval for targeted use cases
Developing oral versions to replace intravenous infusions
Combining with other muscle-supportive agents like myostatin inhibitors

For now, it’s something to watch, especially if you’re someone using GLP-1s and worried about keeping your strength, metabolism, or overall health in check during your weight loss journey.

Interested in a Bimagrumab or Other Clinical Trial?

Clinical trials for next-gen GLP-1 medications and complementary treatments like bimagrumab are happening all the time. Some are focused on weight loss, others on preserving muscle, improving metabolic health, or testing new combinations.

If you’re interested in participating, it’s worth checking trial databases regularly or talking to your healthcare provider about options in your area. We've wrapped up all the information you need to know in the article below.