Over the last couple of years, GLP-1 receptor agonists like semaglutide and tirzepatide have completely changed the obesity treatment landscape. While the weight loss results have been impressive, one concern that continues to come up is the amount of lean body mass that can be lost alongside fat.
Researchers are now turning their attention to a new class of compounds: myostatin inhibitors.
For those unfamiliar, myostatin is a naturally occurring protein that acts as a "brake" on muscle growth. Animals and humans with reduced myostatin activity often exhibit significantly greater muscle mass, which has made this pathway a target of interest for decades. Until recently, however, most attempts to develop practical myostatin-targeting therapies have produced mixed results.
Several next-generation compounds are now being studied specifically to preserve lean tissue during rapid weight loss:
Trevogrumab (REGN1033)
A monoclonal antibody that directly targets myostatin. By neutralizing circulating myostatin, trevogrumab aims to remove one of the primary biological limits on muscle growth and maintenance. It is currently being evaluated in combination with GLP-1 therapies as a way to preserve lean mass during weight reduction.
Garetosmab (REGN2477)
An antibody that targets Activin A, another member of the TGF-beta family involved in regulating muscle growth. Researchers believe that blocking Activin A alongside myostatin inhibition may provide a more complete anabolic effect than targeting myostatin alone.
Bimagrumab
Unlike direct myostatin antibodies, bimagrumab blocks Activin Type II receptors (ActRIIA and ActRIIB), which are responsible for transmitting signals from myostatin and several related proteins. This broader mechanism has generated significant interest because clinical studies have shown increases in lean mass while simultaneously reducing fat mass.
Apitegromab
Originally developed for neuromuscular disorders, apitegromab binds to precursor forms of myostatin and prevents their activation. While not currently as advanced in obesity research as some of the other candidates, it demonstrates another approach to reducing myostatin signaling.
Myo-29 (Stamulumab)
One of the earliest myostatin antibodies ever studied. Although development was ultimately discontinued due to disappointing results, it paved the way for the newer generation of compounds currently in development.
LAE102
A newer investigational antibody being developed to target signaling pathways related to muscle preservation and growth. Early preclinical data have generated interest because of its potential role alongside GLP-1-based weight loss therapies.
AKERO's AKR-7966
A recently announced myostatin-targeting antibody being developed with the goal of preserving muscle during weight loss treatment. This represents part of the growing pharmaceutical trend toward combining incretin therapies with muscle-preserving agents.
The interest is obvious: imagine achieving substantial fat loss from a GLP-1 while minimizing the muscle loss that often accompanies rapid weight reduction. For bodybuilders, strength athletes, and aging populations alike, that could be a major advancement.
The next frontier in obesity treatment may not be simply losing more weight—it's losing the right kind of weight. Pharmaceutical companies are now investing billions into this concept, with the hope that future therapies can preserve muscle, maintain strength, and improve overall body composition while delivering the fat loss benefits we've already seen from GLP-1s.
That said, even if these drugs prove successful, resistance training, adequate protein intake, and proper recovery will likely remain the foundation of maintaining muscle mass during a calorie deficit.
What do you guys think? If a GLP-1 user could maintain nearly all of their lean tissue while dropping body fat, would that change your view of these drugs? Or do you think diet and training will always be the determining factors regardless of what comes down the pharmaceutical pipeline?
Researchers are now turning their attention to a new class of compounds: myostatin inhibitors.
For those unfamiliar, myostatin is a naturally occurring protein that acts as a "brake" on muscle growth. Animals and humans with reduced myostatin activity often exhibit significantly greater muscle mass, which has made this pathway a target of interest for decades. Until recently, however, most attempts to develop practical myostatin-targeting therapies have produced mixed results.
Several next-generation compounds are now being studied specifically to preserve lean tissue during rapid weight loss:
Trevogrumab (REGN1033)
A monoclonal antibody that directly targets myostatin. By neutralizing circulating myostatin, trevogrumab aims to remove one of the primary biological limits on muscle growth and maintenance. It is currently being evaluated in combination with GLP-1 therapies as a way to preserve lean mass during weight reduction.
Garetosmab (REGN2477)
An antibody that targets Activin A, another member of the TGF-beta family involved in regulating muscle growth. Researchers believe that blocking Activin A alongside myostatin inhibition may provide a more complete anabolic effect than targeting myostatin alone.
Bimagrumab
Unlike direct myostatin antibodies, bimagrumab blocks Activin Type II receptors (ActRIIA and ActRIIB), which are responsible for transmitting signals from myostatin and several related proteins. This broader mechanism has generated significant interest because clinical studies have shown increases in lean mass while simultaneously reducing fat mass.
Apitegromab
Originally developed for neuromuscular disorders, apitegromab binds to precursor forms of myostatin and prevents their activation. While not currently as advanced in obesity research as some of the other candidates, it demonstrates another approach to reducing myostatin signaling.
Myo-29 (Stamulumab)
One of the earliest myostatin antibodies ever studied. Although development was ultimately discontinued due to disappointing results, it paved the way for the newer generation of compounds currently in development.
LAE102
A newer investigational antibody being developed to target signaling pathways related to muscle preservation and growth. Early preclinical data have generated interest because of its potential role alongside GLP-1-based weight loss therapies.
AKERO's AKR-7966
A recently announced myostatin-targeting antibody being developed with the goal of preserving muscle during weight loss treatment. This represents part of the growing pharmaceutical trend toward combining incretin therapies with muscle-preserving agents.
The interest is obvious: imagine achieving substantial fat loss from a GLP-1 while minimizing the muscle loss that often accompanies rapid weight reduction. For bodybuilders, strength athletes, and aging populations alike, that could be a major advancement.
The next frontier in obesity treatment may not be simply losing more weight—it's losing the right kind of weight. Pharmaceutical companies are now investing billions into this concept, with the hope that future therapies can preserve muscle, maintain strength, and improve overall body composition while delivering the fat loss benefits we've already seen from GLP-1s.
That said, even if these drugs prove successful, resistance training, adequate protein intake, and proper recovery will likely remain the foundation of maintaining muscle mass during a calorie deficit.
What do you guys think? If a GLP-1 user could maintain nearly all of their lean tissue while dropping body fat, would that change your view of these drugs? Or do you think diet and training will always be the determining factors regardless of what comes down the pharmaceutical pipeline?
