Quick Summary
- Retatrutide is a triple agonist (GLP-1 + GIP + Glucagon), while Tirzepatide is dual (GLP-1 + GIP).
- Retatrutide shows superior fat loss in trials — up to 24% total body weight vs 21% with Tirzepatide.
- Both are long-acting and dosed weekly, but Retatrutide may offer greater energy expenditure and thermogenesis.
- Peptides UK offers COA-verified research peptides, including both compounds.
What Are Retatrutide and Tirzepatide?
Both peptides are part of the incretin-mimetic class, developed to mimic gut hormones that regulate blood sugar, appetite, and fat metabolism.
- Tirzepatide (branded as Mounjaro) is FDA-approved and targets GLP-1 and GIP receptors.
- Retatrutide is under clinical development and targets GLP-1, GIP, and glucagon receptors — making it a triple agonist.
Mechanism of Action: Triple vs Dual Agonist
| Feature | Tirzepatide | Retatrutide |
|---|---|---|
| GLP-1 Activation | ✅ Appetite & insulin | ✅ Appetite & insulin |
| GIP Activation | ✅ Fat metabolism | ✅ Fat metabolism |
| Glucagon Target | ❌ No | ✅ Increases energy burn |
| Fat Oxidation | ✅ Moderate | ✅ High |
| Thermogenesis | ❌ Minimal | ✅ Significant |
Clinical Trial Results: Which Performs Better?
✅ Tirzepatide (SURPASS trials):
- Weight reduction: 15–21% depending on dose (5–15mg/week)
- Approved for type 2 diabetes
- Tolerability: mild to moderate GI effects
✅ Retatrutide (Phase 2 data):
- Weight reduction: 17–24.2% across 12–36 week protocols (5–15mg/week)
- Investigational; not yet approved
- Higher energy expenditure + glucagon-driven fat mobilization
Retatrutide vs Tirzepatide Dosage Comparison
| Week | Tirzepatide (mg) | Retatrutide (mg) |
| 1–2 | 2.5 | 1.0 |
| 3–4 | 5.0 | 2.5 |
| 5–6 | 7.5 | 5.0 |
| 7–8 | 10.0 | 7.5 |
| 9–12 | 12.5–15.0 | 10.0–15.0 |
Both follow slow titration (every 2–4 weeks) for optimal tolerability.
Legal Status and Use in Research
- Tirzepatide is FDA approved for type 2 diabetes; some off-label weight loss use.
- Retatrutide is investigational and available only for research purposes.
- In the UK and Ireland, both peptides can be legally purchased for research use through verified suppliers.
Buy Research-Grade Retatrutide and Tirzepatide
Peptides UK supplies both peptides with:
- ✅ Verified COA on each batch
- ✅ 99%+ purity
- ✅ Fast UK/Ireland shipping
- ✅ Research-use-only compliant packaging
Frequently Asked Questions (FAQs)
Which peptide is better for fat loss: Retatrutide or Tirzepatide?
Clinical data suggests Retatrutide may result in greater total fat loss due to its glucagon receptor activation.
Are both peptides once-weekly?
Yes. Both Retatrutide and Tirzepatide are long-acting and typically dosed once per week.
Can I use either peptide for weight loss?
Only Tirzepatide is FDA approved. Retatrutide is for research only and not for human use.
Disclaimer
This content is for research and educational purposes only. Retatrutide and Tirzepatide are investigational compounds and not approved for human consumption.
