Does apitegromab reduce lean mass loss during weight loss in adults taking tirzepatide?

We’ve reviewed one assertion on this topic, and it suggests that among adults with overweight or obesity taking tirzepatide, weekly injections of apitegromab at 10 mg/kg may help reduce the loss of lean body mass by about 1.9 kilograms over 24 weeks, compared to a placebo, while still allowing the same amount of total weight loss [1]. This is the only piece of evidence we’ve found so far, and it does not contradict any other studies. Lean body mass refers to the weight of your muscles, bones, organs, and water — not fat. Losing too much of it during weight loss can affect strength and metabolism. What we’ve found so far indicates that apitegromab might help preserve this tissue when used alongside tirzepatide, without slowing down overall weight loss. However, this is based on a single assertion, and we have not seen data from longer trials, different doses, or diverse populations. We don’t yet know how consistent this effect is across different groups or whether it lasts beyond 24 weeks. The evidence we’ve reviewed so far leans toward a potential benefit, but more research is needed to understand the full picture. For now, if someone is taking tirzepatide and wants to hold onto muscle while losing weight, this finding may be worth discussing with a healthcare provider — but it’s too early to say whether this approach will work for everyone.