Retatrutide (sometimes shortened in forums as “retatrutide peptide” or even “LY3437943”) is an investigational peptide that blends three hormone pathways—glucagon‑like peptide‑1 (GLP‑1), glucose‑dependent insulinotropic polypeptide (GIP) and glucagon—into one long‑acting molecule. Early trials show extraordinary weight‑loss and metabolic effects, but the drug is still in clinical development, so curious readers often ask: what is retatrutide, and how does it compare with semaglutide, tirzepatide and other modern anti‑obesity medications? This in‑depth guide for peptide enthusiasts, health aficionados and researchers answers that question by explaining how retatrutide works, summarizing the evidence, comparing it with alternatives and highlighting practical considerations for future use.