GLP‑1 weight‑loss injections mainly burn fat, not muscle, in first three months

A 2026 meta‑analysis that combined 24 studies involving more than 1,000 patients treated with GLP‑1 weight‑loss drugs (including semaglutide) showed an average body‑weight reduction of about 9 % after three months. Fat loss accounted for roughly 17 % of body weight and visceral fat decreased markedly, while lean‑tissue loss was only about 2 % (≈ 2 kg). Muscle proportion of body composition and grip‑strength measurements remained stable, suggesting a protective effect on muscle mass.

Researchers propose that GLP‑1 agents may improve muscle blood flow and glucose utilisation, limiting muscle breakdown compared with plain calorie restriction. The advantage wanes after 12 months, especially in older adults, people with sarcopenia, or those with insufficient protein intake. Adequate dietary protein and resistance training are recommended to maintain muscle while using the injections.