New Drug Shows Promise in Reducing Muscle Loss During Weight Loss
A groundbreaking study has revealed that a new drug could significantly reduce muscle loss in patients undergoing weight loss treatments. The research focuses on a medication called apitegromab, which, when combined with weight loss injections, helps preserve muscle mass while maintaining the same level of weight loss as those using the injections alone.
The findings suggest that individuals taking apitegromab alongside their weight loss jabs experience less muscle and bone loss compared to those who only use the injections. This is particularly important because previous studies have shown that up to one-third of the weight lost through these medications comes from muscle and bone rather than fat.
The latest study involved 102 adults who were receiving weekly injections of Mounjaro, also known as tirzepatide. Patients using this medication can lose up to a fifth of their body weight within a year. Half of the participants were given apitegromab, while the other half received a placebo.
Despite both groups experiencing similar overall weight loss, those taking apitegromab lost significantly less lean mass. After six months, the group taking apitegromab lost approximately 1.9 kg less lean mass than those who took the placebo.
Apitegromab is administered every four weeks through an intravenous drip. It works by blocking the activation of myostatin, a protein that regulates muscle mass. When myostatin is active, it can hinder muscle growth. By inhibiting this process, the drug helps maintain muscle mass during weight loss.
Researchers from the AdventHealth Translational Research Institute in the US led the study, which was published in the journal Nature Medicine. According to the phase 2 trial, lean mass accounted for 14.6% of total weight loss in the apitegromab group, compared to 30.2% in the placebo group.
Dr Marie Spreckley from the University of Cambridge commented on the study, stating: “These findings suggest that apitegromab may improve the composition of weight loss by preserving lean mass while maintaining similar overall weight reduction.”
She added: “This is an important area of research because substantial weight loss, whether achieved through medication, dietary interventions or bariatric surgery, is often accompanied by some loss of lean mass.”
“Strategies that help preserve lean mass while maintaining the benefits of weight reduction are of considerable interest, but whether they improve longer-term health outcomes remains to be established.”
“Importantly, although apitegromab preserved lean mass, the study did not demonstrate clear improvements in physical function or cardiometabolic outcomes over the 24-week treatment period.”
“Preserving lean mass is biologically plausible and potentially beneficial, but larger and longer studies will be needed to determine whether these changes translate into meaningful improvements in strength, physical function, quality of life, or long-term health outcomes.”
Rising Use of Weight Loss Injections in the UK
The latest research comes at a time when the use of weight loss injections is increasing rapidly in the UK. NHS figures show a growing number of patients are being prescribed these medications, leading to a significant rise in spending.
NHS spending on blockbuster weight loss jabs has increased fourfold in a year, reaching over half a billion pounds. This makes the cost of the drug higher than any other single medicine the NHS has ever purchased in a single year, according to records spanning 20 years.
In England, medical professionals issued 3.1 million prescriptions for the drug in the 2025/26 financial year, costing £574 million. This trend is also reflected in private prescriptions, where an estimated two and a half million people have purchased the injections.
