New Data Show Lower Activity, Muscle Loss and Mood Changes Linked to GLP‑1 Weight Drugs

Overview

• A wearable‑device study presented at the endocrine meeting found adults with obesity who started GLP‑1 weight drugs reduced average daily steps from about 5,047 to 4,487 and cut moderate‑to‑vigorous activity from 28 to 22 minutes per day.
• An observational analysis reported roughly 40% of patients stop GLP‑1 therapy within one year, nearly 60% by two years, and about 41.5% of those who stop resume treatment within a year; tirzepatide showed lower discontinuation risk than older GLP‑1 agents.
• Clinical and published data document meaningful loss of lean (muscle) mass with these drugs, and a phase‑2 trial found adding apitegromab reduced lean‑mass loss by about 1.9 kg and preserved roughly 54.9% more lean mass over 24 weeks versus placebo, with phase‑3 testing still required.
• Patients and clinicians are reporting emotional side effects such as anhedonia and reduced libido that may reflect GLP‑1 effects on brain reward circuits, leading experts to advise psychiatric screening and dose or drug changes when mood or pleasure decline is severe.
• Physicians urge supervised care that pairs GLP‑1 treatment with high‑protein nutrition, resistance training and monitoring, and surgical societies warn that bariatric surgery remains an essential option while unsupervised or clandestine use poses health risks.