Tirzepatide: Science & Profile
Last updated July 2, 2026 · Medically reviewed by David Chen, MD, PhD
Tirzepatide is a dual agonist: a single molecule that activates both the GLP-1 and GIPreceptors at once. GIP amplifies GLP-1's appetite-suppressing effect and helps blunt nausea, which is part of why tirzepatide tends to outperform single-receptor semaglutide head to head.
Tirzepatide Science
GLP-1 and GIP are hormones your body already makes to regulate hunger and insulin response. Tirzepatide is a single molecule that mimics these 2 hormones at once, so their effects stack.
What the trials show
In SURMOUNT 1 (2022), participants lost roughly 20.9% of body weight at the 15 mg dose over 72 weeks, and the SURMOUNT 5 head-to-head (2025) showed greater weight loss than semaglutide. It also delivers large HbA1c reductions in type 2 diabetes (SURPASS 2) and has shown benefit in obstructive sleep apnea and heart failure.
How it is dosed
Tirzepatide starts at 2.5 mg once weekly and increases by 2.5 mg every four weeks until the target maintenance dose is reached. Model the full schedule and projected loss in the dosing calculator.
Status and side effects
Sold as Mounjaro and Zepbound, tirzepatide is FDA-approved for diabetes and obesity. Side effects are predominantly gastrointestinal and concentrate during escalation; see the full side-effect breakdown or compare it against semaglutide and retatrutide.
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