IGF-1 LR3
Insulin-like Growth Factor 1 Long R3
What is IGF-1 LR3?
IGF-1 LR3 is a synthetic analog of insulin-like growth factor 1 with a modification that reduces binding to IGF-binding proteins, extending the half-life from ~10 minutes (native IGF-1) to approximately 20-30 hours. This dramatically increases bioavailability and anabolic activity.
IGF-1 LR3 binds to IGF-1 receptors on muscle cells, triggering protein synthesis, nitrogen retention, satellite cell activation, and potentially muscle fiber hyperplasia — new cell creation rather than just hypertrophy. It also promotes fat oxidation through receptor signaling in adipose tissue.
Research Evidence
In vitro and animal studies demonstrate significant upregulation of protein synthesis, satellite cell activation, and muscle mass increases. Mechanism is well-characterized at the cellular level.
IGF-1 receptor signaling in fat cells promotes lipolysis. Combined anabolic and fat-mobilizing effects are the basis for body composition protocol use.
Community use in bodybuilding is extensive. Controlled human trials are limited due to regulatory concerns. Anecdotal reports of significant body composition changes are consistent.
Evidence grades: Gold = RCT human data · Silver = multiple animal studies, consistent · Bronze = limited or preliminary
Dosing Protocols
Reconstitution Guide
| Vial Size | BAC Water | Concentration | Target draw |
|---|---|---|---|
| 1 mg | 1 ml | 1000 mcg/ml | 50mcg = 5 units |
| 1 mg | 2 ml | 500 mcg/ml | 50mcg = 10 units |
Frequently Asked Questions
What is the difference between IGF-1 LR3 and regular IGF-1?
The LR3 modification reduces binding to IGF-binding proteins (IGFBPs). Native IGF-1 is rapidly bound by IGFBPs giving it a half-life of ~10 minutes. IGF-1 LR3 has a half-life of 20-30 hours, making it far more bioavailable and longer-acting.
Can IGF-1 LR3 cause hypoglycemia?
Yes — this is the primary safety concern. IGF-1 receptors share significant homology with insulin receptors and can lower blood glucose, especially in a fasted state. Always inject post-meal or post-workout with carbohydrates available.
References
- [1]Ballard FJ, Francis GL, Ross M, et al. Natural and synthetic forms of insulin-like growth factor-1 (IGF-1). Biochem Biophys Res Commun. 1987;149(1):398-404.
- [2]Tomas FM, Knowles SE, Owens PC, et al. Effects of full-length and truncated insulin-like growth factor-I on nitrogen balance. J Endocrinol. 1992;132(1):141-145.
This profile was prepared using AI-assisted research synthesis. Citations are provided where applicable — verify with primary sources before clinical application.
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