This drug can help retain muscle during weight loss
What's the story
A new muscle growth drug could help prevent the loss of lean body mass during weight loss, a study has found. Lean body mass includes non-fat components such as muscles. The research focused on the effects of apitegromab, a monoclonal antibody that blocks myostatin, a protein that inhibits muscle growth. It was found to be effective in retaining lean body mass while using tirzepatide (the active ingredient in Mounjaro).
Trial results
How apitegromab worked in tandem with tirzepatide
In a trial, 102 participants were randomly assigned to two groups. One group was given apitegromab with tirzepatide, while the other received a placebo with tirzepatide. After 24 weeks, both groups showed similar total weight loss. However, those who took apitegromab with tirzepatide lost an average of only 1.6kg of lean mass (14.6% of total weight loss), compared to 3.5kg in the placebo group, indicating a 55% greater retention of lean mass with apitegromab use over placebo alone.
Expert opinion
New drug could improve functionality in people taking GLP-1s
Professor Alexander Miras, an obesity expert at Ulster University, stressed the importance of these findings. He explained that while GLP-1s have been linked to improved "functionality," they also have been associated with muscle mass and strength loss. This new drug could counteract the impact of GLP-1-based drugs on muscle strength and further improve functionality compared to someone not taking this new medication but only tirzepatide.
Future research
Need for larger trials to confirm safety
Professor Naveed Sattar, a cardiometabolic medicine expert at the University of Glasgow, called for larger-scale and longer trials to confirm safety. He said this early-stage trial suggests new drugs can help reduce muscle mass loss with prescribed tirzepatide. However, it's too soon to say if this actually benefits people's health or their ability to move/function better.