Longevity & AgingBimagrumab plus semaglutide boosts weight loss beyond semaglutide alone in phase 2 obesity trial
Most weight lost on obesity drugs is fat, but roughly 25–40% comes from lean tissue such as muscle. Bimagrumab is an antibody that blocks activin type II receptors, which promotes fat loss and muscle growth. This phase 2 trial (BELIEVE) randomized 507 adults with obesity to placebo, bimagrumab, semaglutide, or combinations for 48 weeks, followed by an extension to week 72. At week 48, average weight change was −3.3 kg with placebo, −9.3 kg with high-dose bimagrumab, −14.2 kg with semaglutide 2.4 mg, and −17.8 kg with the high-dose combination. The authors report that the combination preserved lean mass while reducing visceral fat. Bimagrumab was linked to muscle spasms, diarrhea and acne, and more treatment discontinuations due to side effects than other groups.
