IGF-1 LR3
UnregulatedAlso known as: Insulin-like Growth Factor-1 Long R3, Long R3 IGF-1
Growth & AnabolicLast reviewed: April 28, 2026
A synthetic analog of insulin-like growth factor-1 (IGF-1) with an extended half-life due to a modified arginine-3 sequence. IGF-1 is naturally produced in the liver in response to growth hormone. The LR3 variant is approximately 3x more potent than native IGF-1 and resists binding to IGF-binding proteins, extending its activity.
Mechanism of Action
Binds to IGF-1 receptors throughout the body, stimulating cell growth, proliferation, and differentiation. Promotes protein synthesis, glucose uptake, and fat oxidation. Activates the PI3K/Akt/mTOR pathway — the primary anabolic signaling cascade. Unlike GH secretagogues, IGF-1 LR3 acts directly at the tissue level rather than through the pituitary.
Common Uses
- Muscle growth and hypertrophy
- Recovery from injury
- Fat loss
- Anti-aging protocols
- Athletic performance enhancement
Known Risks
- Hypoglycemia (blood sugar drop) — significant risk, especially post-workout
- Potential tumor growth promotion (IGF-1 pathway implicated in cancer)
- Acromegaly-like effects with chronic high-dose use
- Joint pain
- Water retention
- Limited long-term human safety data
- High abuse potential in athletic contexts
Regulatory Status
Not FDA-approved and not on any compounding list. Available as a research chemical. One of the more potent anabolic peptides — the hypoglycemia risk is real and requires careful dosing. Not affected by the 2026 regulatory changes.
Common Protocols
Protocol information is for educational reference only. Dosing varies significantly by individual, condition, and physician guidance. Always work with a licensed healthcare provider.
Subcutaneous or intramuscular injection
Typical Dose
20–100 mcg
Frequency
Once daily post-workout
Cycle Length
4–6 weeks maximum (receptor desensitization risk)
Inject immediately post-workout near the trained muscle group. Eat carbohydrates before injecting to prevent hypoglycemia — this is a real risk. Start at the low end (20 mcg) and assess tolerance. Cycle off for at least equal time to cycle length.
Related Compounds
Research References
This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any peptide therapy. Data is compiled from published research and regulatory sources and may not reflect the most recent developments.