We all know Semaglutide and Tirzepatide. But 2026 is the year of Retatrutide—and it completely rewrites the metabolic playbook. Here’s the breakdown your endocrinology rotation won't teach you (yet): 🔬 The Mechanism (3-for-1) Retatrutide is the first triple agonist: → GLP-1 (appetite suppression) → GIP (enhances insulin sensitivity, reduces nausea) → Glucagon (THIS is the game-changer) ⚡ Why Glucagon matters: For decades, we suppressed glucagon. Now we're activating it—in a pulsatile way. It directly stimulates energy expenditure (calorie burn) rather than just calorie restriction. In Phase 2 trials, subjects lost ~24% body weight at 48 weeks—a full 10% more than Tirzepatide—without a massive increase in side effects. 🧠 The "Oh Wow" for Med Students: Retatrutide showed unprecedented reduction in liver fat fraction (over 70% decrease in 24 weeks). That means it's currently being fast-tracked for MASH (Metabolic Dysfunction-Associated Steatohepatitis)—a condition with exactly zero good oral options right now. 📉 The Clinical Catch: Heart rate increases by ~5-10 bpm in the first 8 weeks. It's dose-dependent, it plateaus, and it's reversible—but if your patient has uncontrolled hypertension or pre-existing CAD, you pause and think twice. This isn't a "give and forget" drug. The Bigger Picture Takeaway: We are watching metabolic medicine shift from "restrict calories" to "restructure energy homeostasis." The receptor combinatorics alone (GLP-1 + GIP + Glucagon, or GLP-1 + Amylin + Calcitonin in future candidates) is becoming its own subspecialty. --- 🔬 Journal Club Question for the comments: If you had a 45-year-old obese patient with HFpEF (heart failure with preserved ejection fraction) and MASH—and their insurance denies Retatrutide—what's your second-line peptide alternative, and why? (Drop your reasoning—let's crowdsource this clinical dilemma.) 👇