Comparison
Follistatin-344 vs IGF-1 LR3
Follistatin-344 is myostatin inhibitors; IGF-1 LR3 is IGF & growth factors. They are compared here because they are frequently considered against each other, not because they act alike.
| Follistatin-344 | IGF-1 LR3 | |
|---|---|---|
| Class | Myostatin inhibitors | IGF & growth factors |
| Evidence | Animal models only | Animal models only |
| Human trials | ~1 | None published |
| Half-life | ~30 minutes | ~20-30 hours |
| Reported range | 100-300 mcg | 20-50 mcg |
| Frequency | Once daily, short cycles | Once daily |
| Routes | Subcutaneous, Intramuscular | Subcutaneous, Intramuscular |
| FDA approved | No | No |
| Research use only | Yes | Yes |
| Banned in sport | Yes | Yes |
| Studied for | Muscle hypertrophy research, Muscular dystrophy gene therapy research | Muscle hypertrophy research, Cell-culture growth supplement, Recovery |
| Reported side effects | Injection-site reactions, Headache, Poorly characterised | Hypoglycaemia, Injection-site swelling, Headache, Jaw pain |
Follistatin-344
Follistatin-344 is a precursor isoform of the endogenous glycoprotein follistatin, which binds and neutralises activin A and myostatin. Removing myostatin inhibition permits muscle hypertrophy and hyperplasia, an effect demonstrated dramatically in gene-therapy animal models. The injectable protein is cleared within minutes and does not reproduce those results, which is the key practical caveat: the striking animal data comes from sustained genetic expression, not from injections.
IGF-1 LR3
IGF-1 LR3 substitutes arginine for glutamic acid at position 3 and adds a 13-residue N-terminal extension. The position-3 substitution sharply reduces affinity for IGF binding proteins, so a much larger fraction remains free and active in circulation, extending the functional half-life from minutes to more than a day. It activates the IGF-1 receptor to drive protein synthesis, satellite-cell proliferation and hyperplasia, and it also has appreciable affinity for the insulin receptor, which accounts for its hypoglycaemic effect.
Follistatin-344 vs IGF-1 LR3: common questions
What is the difference between Follistatin-344 and IGF-1 LR3?
Follistatin-344 is myostatin inhibitors and IGF-1 LR3 is IGF & growth factors, so they act on different pathways. Follistatin-344: A natural myostatin-binding glycoprotein, of interest for muscle growth but with a very short circulating half-life. IGF-1 LR3: An IGF-1 analog modified to evade binding proteins, giving it far longer activity than native IGF-1.
Which has stronger evidence, Follistatin-344 or IGF-1 LR3?
They sit at the same evidence level: animal models only. Follistatin-344 has about 1 human studies and IGF-1 LR3 about 0.
Are Follistatin-344 and IGF-1 LR3 FDA approved?
Neither is FDA approved for any indication.
References
Regulatory and primary sources
- WADA Prohibited List ↗ · current year
- FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
- CAS Registry Number 946870-92-4 ↗ · chemical identity
Published literature
- Relative Energy Deficiency in Sport (REDs): Endocrine Manifestations, Pathophysiology and Treatments.Endocr Rev 2024.PubMed 38488566 · doi:10.1210/endrev/bnae011
- Effects of 16 Weeks of Resistance Training on Muscle Quality and Muscle Growth Factors in Older Adult Women with Sarcopenia: A Randomized Controlled Trial.Int J Environ Res Public Health 2021.PubMed 34201810 · doi:10.3390/ijerph18136762
- Effectiveness of low-load resistance training with blood flow restriction vs. conventional high-intensity resistance training in older people diagnosed with sarcopenia: a randomized controlled trial.Sci Rep 2024.PubMed 39558011 · doi:10.1038/s41598-024-79506-9
- Adipokines, Hepatokines and Myokines: Focus on Their Role and Molecular Mechanisms in Adipose Tissue Inflammation.Front Endocrinol (Lausanne) 2022.PubMed 35909571 · doi:10.3389/fendo.2022.873699
- Hormonal treatments for endometriosis: The endocrine background.Rev Endocr Metab Disord 2022.PubMed 34405378 · doi:10.1007/s11154-021-09666-w
- Transcytosis of LDL Across Arterial Endothelium: Mechanisms and Therapeutic Targets.Arterioscler Thromb Vasc Biol 2025.PubMed 40013359 · doi:10.1161/ATVBAHA.124.321549
- The impact of weight loss on fat-free mass, muscle, bone and hematopoiesis health: Implications for emerging pharmacotherapies aiming at fat reduction and lean mass preservation.Metabolism 2024.PubMed 39481534 · doi:10.1016/j.metabol.2024.156057
- Effects of 12-week whole-body vibration training versus resistance training in older people with sarcopenia.Sci Rep 2025.PubMed 40011687 · doi:10.1038/s41598-025-91644-2
- Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris.Appl Microbiol Biotechnol 2023.PubMed 37261455 · doi:10.1007/s00253-023-12606-0
- IGF-1 has plaque-stabilizing effects in atherosclerosis by altering vascular smooth muscle cell phenotype.Am J Pathol 2011.PubMed 21281823 · doi:10.1016/j.ajpath.2010.10.007
- Novel insulin-like growth factor-methotrexate covalent conjugate inhibits tumor growth in vivo at lower dosage than methotrexate alone.Transl Res 2009.PubMed 19446281 · doi:10.1016/j.trsl.2009.02.005
- 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.J Alzheimers Dis 2025.PubMed 39610283 · doi:10.1177/13872877241299056
- The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.Front Endocrinol (Lausanne) 2026.PubMed 42395176 · doi:10.3389/fendo.2026.1822475
- Involvement of insulin-like growth factor-1 and its binding proteins in proliferation and differentiation of murine bone marrow-derived macrophage precursors.Endocrine 1998.PubMed 9867252 · doi:10.1385/ENDO:9:2:185
Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.