Potential Drug Benefits Muscle Retention During Weight Loss
A recent study indicates that a drug promoting muscle growth might help lessen the loss of lean body mass associated with weight-loss injections.
GLP-1-based injections, like Wegovy and Mounjaro, have proven quite effective for those who are overweight or obese. However, specialists caution that not all weight lost is beneficial; research has shown that 25-40% of total weight loss can actually come from a decrease in lean body mass, which includes muscle.
The researchers emphasized the importance of maintaining lean body mass, as it plays a crucial role in overall health and physical strength. Lean tissue burns more calories than fat and is also associated with a reduced risk of type 2 diabetes.
A small clinical trial has suggested that a monoclonal antibody named apitegromab may help preserve lean body mass during weight loss with tirzepatide, the active ingredient in Mounjaro. Apitegromab functions by inhibiting myostatin, a protein that restricts muscle development.
Professor Alexander Miras, an obesity specialist at Ulster University who was not part of the study, considered the findings significant. He pointed out that while GLP-1s have been linked to better day-to-day functionality, they also correlate with muscle loss and diminished strength.
“This implies that people might find it harder to perform tasks like lifting heavy objects or climbing hills,” Miras noted. “The new medication could help counteract the effects of GLP-1 drugs on muscle strength, potentially enhancing overall functionality for those using tirzepatide in conjunction with it.”
In research published in Nature Medicine, scientists from the U.S. divided 102 participants into two groups: 51 received apitegromab with tirzepatide, while the other half took a placebo alongside tirzepatide.
After 24 weeks, the results showed comparable total weight loss between both groups.
However, those who received apitegromab alongside tirzepatide lost an average of 1.6 kg (3.5 lb) of lean mass, which accounted for 14.6% of total weight loss. In contrast, participants given a placebo saw an average lean mass loss of 3.5 kg. This indicates that apitegromab use led to a 55% better retention of lean mass compared to the placebo.
The researchers noted that side effects were similar in frequency across both groups, with the majority being mild. Still, limitations exist in the study, such as a predominant female participant group and its relatively small, short-term nature.
Professor Naveed Sattar, an expert in cardiometabolic medicine at the University of Glasgow, stated that more extensive and longer trials are essential, especially for safety assessment.
“While this initial trial suggests that new drugs can help reduce muscle mass loss when using prescribed tirzepatide, it’s premature to conclude whether such drugs truly improve health or functionality,” he remarked.
“In the meantime, those on these medications should be encouraged to boost their physical activity, as it can help maintain muscle mass naturally. It’s vital that this activity is seen as enjoyable and sustainable rather than just a clinical requirement,” he added.
