IGF-1 LR3
A modified version of IGF-1 with extended half-life and reduced IGF binding protein affinity, used for muscle growth.
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This information is for educational purposes. Peptide therapy should be guided by a licensed healthcare provider. Connect with a Noho clinician
What is IGF-1 LR3?
IGF-1 LR3 is a modified form of insulin-like growth factor 1 with an arginine substitution at position 3 and a 13-amino acid N-terminal extension. These modifications dramatically reduce binding to IGF binding proteins (IGFBPs), increasing its bioavailability and half-life from ~15 minutes to ~20 hours. It is primarily used in research and by bodybuilders for muscle growth.
Why People Talk About It
Enhanced muscle growth (hyperplasia)
EmergingExtended IGF-1 activity vs native IGF-1
ModerateRecovery from training
EmergingHow It Works
IGF-1 LR3 is a supercharged version of the body's main growth signal. It promotes muscle cell growth and even the creation of new muscle cells, while lasting much longer in the body than natural IGF-1.
Common Questions
Safety Information
Common Side Effects
Cautions
- • Significant hypoglycemia risk
- • May promote growth of existing tumors
- • Not FDA-approved
- • Organ growth with chronic use
What We Don't Know
Long-term safety is poorly characterized. Theoretical cancer risk from chronic IGF-1R activation.
Published Research
20 studiesThe role of the insulin-like growth factor 1 (IGF-1) in skeletal muscle physiology
Type I insulin-like growth factor receptor signaling in skeletal muscle regeneration and hypertrophy
IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep
Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration
Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets
Impaired muscle regeneration and myoblast differentiation in mice with a muscle-specific KO of IGF-IR
Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats.
IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys.
Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection.
Insulin-like growth factor-I and more potent variants restore growth of diabetic rats without inducing all characteristic insulin effects.
Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs.
Prolonged administration of IGF peptides enhances growth of gastrointestinal tissues in normal rats.
Treatment with IGF-I peptides improves function of the remnant gut following small bowel resection in rats.
Preferential intestinal delivery of long[Arg3] insulin-like growth factor (LR3IGF-I) over IGF-I in preweaning and adult rats.
Transport of circulating IGF-I and LR3IGF-I from blood to extracellular wound fluid sites in rats.
Effects of insulin-like growth factor-I and LR3IGF-I on regional blood flow in normal rats.
The role of insulin-like growth factors in small intestinal cell growth and development.
Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice.
Insulin-like growth factor-I and analogues increase growth in artificially-reared neonatal pigs.
Effects of chronic renal failure on plasma clearance of insulin-like growth factor I, des-(1-3)IGF-I, and LR3IGF-I.
Always consult a qualified clinician
This information is for educational purposes. Peptide therapy should be guided by a licensed healthcare provider. Connect with a Noho clinician
Related Peptides
IGF-1 DES
EmergingA truncated form of IGF-1 missing the first 3 amino acids, with 10x greater potency and very short half-life for localized effects.
MGF
EmergingA splice variant of IGF-1 produced in response to mechanical stress on muscles, promoting satellite cell activation and muscle repair.
PEG-MGF
PreliminaryA PEGylated version of MGF with extended half-life for systemic muscle growth and recovery effects.
MK-677
ModerateAn orally active growth hormone secretagogue that mimics ghrelin to stimulate GH and IGF-1 release.
Quick Facts
- Class
- Growth Factor Analogue
- Evidence
- Emerging
- Safety
- Limited Data
- Updated
- Mar 2026
- Citations
- 20PubMed
Also known as
Tags
Related Goals
Evidence Score
Clinical Trials
View Clinical TrialsLinks to ClinicalTrials.gov for reference. Listing does not imply endorsement.
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