IGF-1 LR3 vs PEG-MGF vs Sermorelin
A three-way comparison to help you find the right peptide for your research goals.
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 →PEG-MGF
PEG-MGF (PEGylated Mechano Growth Factor) is a variant of IGF-1 that is produced in response to muscle damage. PEGylation extends its half-life from minutes to several hours, making it practical for use.
Full details →Sermorelin
Sermorelin is a synthetic analog of GHRH consisting of the first 29 amino acids of the natural hormone. It was previously FDA-approved for GH deficiency diagnosis and treatment in children.
Full details →Side-by-Side Comparison
| Aspect | IGF-1 LR3 | PEG-MGF | Sermorelin |
|---|---|---|---|
| Mechanism | 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. | Activates muscle satellite cells (stem cells) and promotes their fusion to existing muscle fibers for repair and growth. MGF is produced naturally in response to mechanical stress on muscles. | Binds to GHRH receptors in the pituitary gland to stimulate natural GH production and release. Maintains the body's natural feedback mechanisms for GH regulation. |
| Typical Dosage | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. | Research protocols typically use 200-400mcg injected into targeted muscle groups 2-3 times weekly, usually post-workout. | Typical dosing: 200-500mcg administered once daily, usually before bed. Some protocols use twice daily dosing. |
| Administration | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. | Intramuscular injection, ideally into muscles trained that day. Best administered post-workout when satellite cell activation is relevant. | Subcutaneous injection, preferably at bedtime to work with natural GH release patterns. Can be combined with GHRPs for synergistic effects. |
| Side Effects | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. | Injection site soreness, potential hypoglycemia, and localized swelling. Generally well-tolerated. | Generally well-tolerated. May cause injection site reactions, headache, flushing, or dizziness. Less side effects than direct GH administration. |
| Best For |
What They Have in Common
IGF-1 LR3, PEG-MGF, Sermorelin are all commonly used for:
Key Differences
Unique to IGF-1 LR3:
Unique to Sermorelin:
Detailed Analysis
Commonalities
Both IGF-1 LR3 and PEG-MGF are commonly used for Muscle Growth, Recovery & Healing.
Which Should You Choose?
IGF-1 LR3 has stronger evidence for Muscle Growth.
Commonalities
Both IGF-1 LR3 and Sermorelin are commonly used for Muscle Growth, Fat Loss, Recovery & Healing.
Which Should You Choose?
IGF-1 LR3 has stronger evidence for Muscle Growth.
Commonalities
Both PEG-MGF and Sermorelin are commonly used for Muscle Growth, Recovery & Healing.
Which Should You Choose?
Both peptides have similar evidence levels for their shared goals. Your choice may depend on specific use case, availability, or personal response.