The dual GLP-1 / GIP agonist behind Mounjaro and Zepbound — delivering the largest weight-loss results seen in any approved medication to date.
Tirzepatide is a dual agonist that activates both the GLP-1 receptor (like semaglutide) and the GIP receptor (glucose-dependent insulinotropic polypeptide). The combined signal produces greater insulin sensitivity, appetite suppression, and fat loss than single-receptor GLP-1s.
FDA approved as Mounjaro (type 2 diabetes, 2022) and Zepbound (obesity, 2023). The SURMOUNT-1 trial showed an average 20.9% body-weight loss at the 15 mg dose — roughly 40% better than semaglutide’s best-case result.
FDA approved. Prescription-only. Available from compounding pharmacies and research suppliers (outside official supply chain). Not WADA prohibited.
Same mechanism as semaglutide: reduces appetite, slows gastric emptying, enhances glucose-dependent insulin release. Provides the core appetite and glycemic control.
GIP enhances fat metabolism and improves glucose handling in adipose tissue, while partially offsetting GLP-1’s GI side effects. Early data suggest GIP may help preserve lean mass during weight loss.
The dual agonism produces greater HbA1c reductions, larger weight loss, and better insulin sensitivity than either receptor alone — true pharmacological synergy.
Tirzepatide has one of the most rapidly expanding evidence bases in metabolic medicine — SURPASS (diabetes) and SURMOUNT (obesity) Phase 3 programs covered tens of thousands of patients.
| Benefit | Evidence |
|---|---|
| Weight loss | SURMOUNT-1: ~20.9% body-weight loss at 15 mg over 72 weeks |
| HbA1c reduction | SURPASS program: HbA1c drops up to 2.5% at 15 mg in type 2 diabetes |
| Sleep apnea | SURMOUNT-OSA (2024): clinically meaningful reductions in AHI in obese OSA patients |
| MASH / NAFLD | Significant improvements in liver fat content and fibrosis markers |
| Cardiovascular risk | SURPASS-CVOT ongoing; existing data suggest CV safety, favorable lipid changes |
| Heart failure | SUMMIT trial (2024): improved outcomes in HFpEF with obesity |
Build your protocol, log every dose, monitor your body's response, and get reminders so you never miss a dose.
Start Tracking FreeEach step is 4 weeks minimum. Extend steps if side effects are significant — do not advance early.
| Weeks | Weekly Dose |
|---|---|
| 1–4 | 2.5 mg |
| 5–8 | 5 mg |
| 9–12 | 7.5 mg |
| 13–16 | 10 mg |
| 17–20 | 12.5 mg |
| 21+ | 15 mg (max) |
Many users stop titrating once they hit a dose that provides satisfying appetite control without side effects — often 5, 7.5, or 10 mg. Max dose isn’t always necessary.
Research tirzepatide typically comes as a 10 mg or 30 mg lyophilized vial. Branded Mounjaro/Zepbound pens come pre-filled.
10 mg vial + 2 mL BAC water = 5 mg/mL
| Dose | Volume | Syringe Units |
|---|---|---|
| 2.5 mg | 0.50 mL | 50 units |
| 5 mg | 1.00 mL | 100 units |
| 7.5 mg | 1.50 mL | 150 units (split if needed) |
| 10 mg | 2.00 mL | 200 units |
For higher doses (12.5 & 15 mg) reconstitute with less BAC water (1 mL → 10 mg/mL) to keep injection volume manageable. 10 mg vial at 2.5 mg/week = 4 weeks; at 10 mg/week = 1 week.
Use our free peptide calculator to figure out your reconstitution volume, draw amount, and syringe units.
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Tirzepatide has a similar side effect profile to semaglutide, with slightly better GI tolerance at equivalent efficacy (the GIP component appears to reduce nausea).
FDA boxed warning for thyroid C-cell tumors (rodent data). Avoid with MTC or MEN2 history.
Tirzepatide vs. semaglutide?
The 2025 SURMOUNT-5 head-to-head trial (PMID 40353578) in obesity without T2D showed ~20.2% weight loss with tirzepatide vs. ~13.7% with semaglutide at 72 weeks at maximum tolerated doses — a meaningful advantage for tirzepatide, but not the “40% more” often cited in cross-trial comparisons. The earlier SURPASS-2 head-to-head was in T2D vs. semaglutide 1 mg (not 2.4 mg). GI tolerance is similar or slightly better; tirzepatide is more expensive.
Sleep apnea benefit?
Worth noting for anyone with comorbid OSA: PMID 38912654 (SURMOUNT-OSA) demonstrated clinically meaningful reductions in apnea-hypopnea index with tirzepatide in patients with moderate-to-severe OSA and obesity.
Do I need to strength train?
Yes — rapid weight loss causes muscle loss. Resistance training 2–3×/week plus 1 g protein per pound lean mass is essential to preserve muscle.
Can I switch from semaglutide to tirzepatide?
Yes. Most clinicians restart at 2.5 mg tirzepatide for 4 weeks, then titrate up. Some start at 5 mg if already established on 1.7+ mg semaglutide.
Can I stop once I’m at goal weight?
Most people regain weight when stopped. SURMOUNT-4 (PMID 38078870) directly quantified this: participants who switched to placebo after 36 weeks of tirzepatide regained roughly 50% of the lost weight over the following 52 weeks, while those who continued tirzepatide maintained their loss. Long-term maintenance dosing (5–10 mg) or a very structured taper with sustained nutrition/training is usually needed.
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StackTrax guides cover peptides and compounds that are not FDA-approved for the uses discussed. The dosing, reconstitution, and safety information is compiled from published research and community protocols for educational purposes only.
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