IGF-1 LR3
IGF-1 LR3 is a recombinant analog of endogenous IGF-1 with an arginine substitution at position 3 and a 13-amino acid N-terminal extension that dramatically reduces affinity for IGF binding proteins (IGFBPs), which normally sequester circulating IGF-1 and limit receptor access. This modification extends its plasma half-life from roughly 10 minutes (native IGF-1) to approximately 20–30 hours, enabling sustained downstream signaling at the IGF-1 receptor. It promotes muscle satellite cell activation, protein synthesis, fat oxidation, and glucose uptake in preclinical models, making it of high interest for muscle hypertrophy and tissue repair research. Sustained systemic IGF-1 elevation carries meaningful risks including hypoglycemia, acromegaly-like effects at high doses, and theoretical mitogenic concerns; no human clinical trials or regulatory approvals exist for IGF-1 LR3.
Evidence last reviewed: 19 Apr 2026
Not a routine supplement — not recommended for self-directed use.
Information here is educational only, not a recommendation to use. See our Safety page.
Verify this peptide on CertiPep
certipep.ch — anonymous purity & characterization service
Evidence is from research or clinical settings — does not imply safety outside supervised contexts.
The evidence for IGF-1 LR3 is primarily based on very low-quality case series, suggesting potential benefits for muscle growth and tissue repair. However, the absence of human clinical trials and documented risks limits its practical application.
Muscle growthGeneral population · Case seriesVery low
IGF-1 LR3 is theorized to enhance muscle growth by activating satellite cells and promoting anabolic signaling.
Tissue repairAthletes · Case seriesVery low
IGF-1 LR3 may aid in tissue repair by enhancing cellular regeneration processes.
Anabolic signalingBodybuilders · Case seriesVery low
IGF-1 LR3 is believed to enhance anabolic signaling pathways, potentially leading to increased muscle mass.