Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| HGH (Somatropin) | IGF-1 LR3 | |
|---|---|---|
| Category | Growth Factors | Growth Factors |
| Standard Dose | Research indicates 1-2 IU daily for anti-aging and general optimization. 2-4 IU daily for body composition. 4-8+ IU daily in clinical GH deficiency (physician-supervised only). | Research indicates 20-50 mcg daily via subcutaneous or intramuscular injection. |
| Timing | Bedtime injection (mimics natural nocturnal GH surge) or morning fasted. Split dosing (AM + pre-bed) for higher doses. Always on empty stomach — carbohydrates blunt GH action. | Post-workout administration for muscle growth. Can be injected locally (intramuscularly) into target muscle groups. Morning dosing on rest days. |
| Cycle Duration | Continuous use is common in anti-aging protocols. 6-12 month minimum for full benefits. Clinical GHD treatment is typically lifelong. | 4-6 week cycles maximum. Longer cycles risk significant side effects and receptor desensitization. |
| Evidence Level | strong_human | moderate_human |
Human Growth Hormone (somatropin) is a 191-amino acid single-chain polypeptide produced by anterior pituitary somatotrophs. It binds the GH receptor (GHR), activating JAK2-STAT5 signaling and MAP kinase pathways. Systemically, HGH upregulates hepatic IGF-1 production, which mediates most of its anabolic effects through IGF-1R/PI3K/Akt/mTOR-driven protein synthesis. Direct GH effects include lipolysis activation, insulin antagonism, chondrocyte/osteoblast stimulation, and enhanced collagen synthesis. Effects are divided into direct (lipolysis, insulin antagonism) and indirect (IGF-1-mediated growth and anabolism).
Research indicates 1-2 IU daily for anti-aging and general optimization. 2-4 IU daily for body composition. 4-8+ IU daily in clinical GH deficiency (physician-supervised only).
Bedtime injection (mimics natural nocturnal GH surge) or morning fasted. Split dosing (AM + pre-bed) for higher doses. Always on empty stomach — carbohydrates blunt GH action.
Continuous use is common in anti-aging protocols. 6-12 month minimum for full benefits. Clinical GHD treatment is typically lifelong.
IGF-1 LR3 (Long Arginine 3-IGF-1) is an 83-amino acid synthetic analog of IGF-1 with an arginine substitution at position 3 and 13 additional N-terminal amino acids. These modifications eliminate binding to IGF-binding proteins, making it approximately 3x more potent than native IGF-1 with a half-life of 20-30 hours (vs 12-15 minutes for native IGF-1). It activates the IGF-1R tyrosine kinase receptor, triggering IRS-1/PI3K/Akt/mTOR and PI3K/Akt/GSK3-beta pathways to drive protein synthesis, muscle hypertrophy, and hyperplasia (new muscle cell formation).
Research indicates 20-50 mcg daily via subcutaneous or intramuscular injection.
Post-workout administration for muscle growth. Can be injected locally (intramuscularly) into target muscle groups. Morning dosing on rest days.
4-6 week cycles maximum. Longer cycles risk significant side effects and receptor desensitization.
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