Retatrutide vs IGF-1 LR3
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Retatrutide
Retatrutide is an investigational triple agonist targeting GIP, GLP-1, and glucagon receptors. Phase 2 trials showed unprecedented weight loss of up to 24% at 48 weeks, making it potentially the most effective obesity treatment studied.
Full details →IGF-1 LR3
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified version of IGF-1 with extended half-life and enhanced potency. The modifications prevent binding to IGF binding proteins, increasing bioavailability.
Full details →Side-by-Side Comparison
| Aspect | Retatrutide | IGF-1 LR3 |
|---|---|---|
| Mechanism | Triple receptor activation provides complementary metabolic effects: GLP-1 and GIP reduce appetite and improve insulin sensitivity, while glucagon receptor activation increases energy expenditure and promotes hepatic fat oxidation. | Binds to IGF-1 receptors to promote protein synthesis, muscle growth, and fat metabolism. The LR3 modification (13 amino acid extension and arginine substitution) extends half-life from minutes to 20-30 hours. |
| Typical Dosage | Clinical trials used doses from 1mg to 12mg weekly. Optimal dosing still being determined in ongoing Phase 3 trials. | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. |
| Administration | Subcutaneous injection once weekly. Currently only available through clinical trials - not yet FDA approved. | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. |
| Side Effects | Similar GI effects to other incretin-based therapies: nausea, diarrhea, vomiting, constipation. Dose-dependent severity. | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. |
| Best For |
What They Have in Common
Both Retatrutide and IGF-1 LR3 are commonly used for: