Nat Med

Combination therapy shows superior weight and fat‑mass reduction in phase 2 obesity trial

March 10, 2026

The phase 2 BELIEVE trial (NCT05616013) found that combining bimagrumab with semaglutide produced substantially greater weight and fat‑mass reduction compared with either therapy alone. In adults with obesity, the highest‑dose combination yielded an average weight loss of 17.8 kg at 48 weeks vs. 9.3 kg with bimagrumab alone and 14.2 kg with semaglutide alone, with continued improvement through week 72. Safety profiles were consistent with known effects of each drug. Importantly, bimagrumab’s activin‑receptor–blocking mechanism appeared to help preserve lean mass, addressing a key limitation of GLP‑1–based therapies, which can contribute to significant muscle loss.

Clinical takeaway: When treating patients with obesity—particularly those at risk for low muscle mass—consider that emerging combination strategies like bimagrumab plus semaglutide may offer enhanced fat‑mass reduction while better preserving lean tissue, though these agents remain investigational and are not yet available for clinical use.

Source:

Heymsfield SB, et al; BELIEVE trial investigators. (2026, March 2). Nat Med. Bimagrumab plus semaglutide alone or in combination for the treatment of obesity: a randomized phase 2 trial. https://pubmed.ncbi.nlm.nih.gov/41772149/