Mounjaro is the brand name for tirzepatide, a first-in-class dual GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptor agonist developed by Eli Lilly. FDA-approved in May 2022 for type 2 diabetes, it has rapidly become the most prescribed new weight-loss medication in the United States — largely due to its superior efficacy over semaglutide in head-to-head clinical trials.
Unlike semaglutide which only activates GLP-1 receptors, tirzepatide activates both GIP and GLP-1 receptors simultaneously. GIP receptors are expressed throughout the body including fat tissue, muscle, and the central nervous system. This dual action creates a more powerful and complementary appetite-suppressing and metabolic effect than a single receptor approach alone.
In the SURMOUNT-1 trial, patients on 15mg tirzepatide lost an average of 22.5% of their body weight over 72 weeks — the highest weight loss ever recorded for an FDA-approved non-surgical intervention. In the direct head-to-head SURMOUNT-5 trial (2025), tirzepatide produced 20.2% weight loss versus 13.7% for semaglutide 2.4mg.











