New drug may prevent muscle loss from obesity injections

Study finds apitegromab helps preserve muscle mass during weight loss treatment with GLP-1 medications such as Mounjaro and Wegovy.

A new experimental drug, apitegromab, may help people using popular obesity medications maintain muscle mass while losing weight, according to new research published in the journal Nature Medicine.

Researchers found that people taking GLP-1 weight-loss drugs, such as Wegovy, Mounjaro and Ozempic, can lose a significant amount of muscle along with fat during rapid weight reduction.

The study, conducted in the United States, involved 102 adults, most of whom were women. Participants received the obesity medication Mounjaro, while some were also given apitegromab. Body scan results showed that those receiving the additional treatment preserved substantially more muscle mass while continuing to lose body fat.

According to the findings, muscle or lean mass accounted for only 14.6% of total weight loss among participants receiving apitegromab, compared with 30.2% in the placebo group. Researchers reported that participants maintained approximately 1.9 kilograms, or 55% more muscle mass, than those who did not receive the drug.

The research comes amid growing attention to the side effects of rapid weight loss associated with GLP-1 medications. Some users have reported noticeable changes in body shape, including loss of muscle and tissue volume, a phenomenon popularly referred to as “Ozempic butt.” Experts note that these effects are linked to rapid weight loss rather than the medications themselves.

Apitegromab works by blocking a protein involved in muscle breakdown. The drug is currently being studied for other muscle-related conditions, including Spinal Muscular Atrophy.

Medical experts welcomed the findings but cautioned that more extensive research is needed before the treatment can be widely recommended. Researchers emphasized that larger and longer-term studies are required to determine whether preserving muscle mass leads to improved strength, wellbeing, and long-term health outcomes.

Health professionals continue to recommend strength training and adequate protein intake for people using weight-loss medications. Activities such as weightlifting, resistance exercises, cycling, stair climbing, yoga, and gardening can help maintain muscle mass. Nutrition experts also advise consuming sufficient protein through foods such as meat, fish, eggs, beans, lentils, chickpeas, nuts, and yogurt.

Apitegromab remains an investigational treatment and is currently available only through clinical trials.