London: A new experimental drug could help people taking popular obesity medications avoid significant muscle loss while still achieving weight reduction, according to research published in the journal Nature Medicine.
The drug, known as apitegromab, was tested alongside the weight-loss medication Mounjaro in a clinical trial involving 102 adults. Researchers found that participants who received the new treatment maintained significantly more muscle mass compared with those who received a placebo.
Health experts have raised concerns that a substantial portion of weight lost through GLP-1 medications such as Wegovy, Ozempic and Mounjaro can come from muscle rather than fat.
Rapid weight loss may also lead to changes in body shape, including what has become popularly known as “Ozempic butt,” a term used to describe a loss of fat and tissue volume in certain areas of the body.

The study found that participants taking apitegromab retained around 55 percent more muscle mass than those who did not receive the treatment. Researchers believe the drug works by blocking a protein involved in muscle breakdown, helping preserve lean tissue during weight loss.
Scientists caution that the findings remain preliminary and larger, longer-term studies are needed before the treatment can be widely recommended. Researchers also want to determine whether preserving muscle mass translates into better strength, physical function and overall health outcomes.
Currently, apitegromab is available only through clinical trials and is administered through intravenous infusion. However, developers are exploring the possibility of creating a self-injectable version similar to existing weight-loss medications.
Experts continue to stress that people using obesity treatments should maintain a balanced diet rich in protein and incorporate regular strength-building exercise into their routines. These measures remain important for protecting muscle mass and supporting long-term health during weight loss.

