{"id":"peg-mgf","name":"PEG-MGF","aliases":["mechano growth factor","MGF","IGF-1Ec","pegylated mechano growth factor"],"url":"https://lyoresearch.com/compounds/peg-mgf","class":{"id":"growth-hormone-and-igf","name":"Growth hormone, IGF-1 and growth factors","url":"https://lyoresearch.com/classes/growth-hormone-and-igf"},"summary":"Mechano growth factor is a splice variant of IGF-1 that muscle makes briefly after loading or damage; its distinctive tail is thought to signal muscle stem cells to divide. PEG-MGF is a synthetic version of that tail with polyethylene glycol attached to make it last longer, sold for muscle repair and growth. No human study has ever administered it: the entire human literature measures how much MGF muscle expresses after exercise, growth hormone or ultrasound. It is not approved anywhere and is named on the Prohibited List.","overall_grade":"D","overall_grade_meaning":"no human evidence","human_trials":"0 — every human study measures the body's own MGF","regulatory_status":"Not approved; research reagent","molecule":{"formula":null,"molecular_weight":null,"cas":null,"pubchem_cid":null,"note":"A pegylated peptide with no single defined structure in public databases"},"pharmacokinetics":{"basis":"none","route":"Injected as sold; no human study","half_life":"No human pharmacokinetic data","licensed_regimen":null,"product":null,"source":null},"outcomes":[{"outcome":"Muscle growth or repair (injected)","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"0 controlled","evidence":"No human study of any design has given MGF or PEG-MGF. Claims rest on rodent injections and on human studies that only measured natural MGF expression.","references":[{"citation":"Hameed M, Lange KH, Andersen JL, et al. The effect of recombinant human growth hormone and resistance training on IGF-I mRNA expression in the muscles of elderly men.","where":"J Physiol, 2004","url":"https://pubmed.ncbi.nlm.nih.gov/14565994/"},{"citation":"Searches of PubMed and trial registries for administered mechano growth factor or PEG-MGF in humans.","where":"LYO literature search, September 2026","url":"https://pubmed.ncbi.nlm.nih.gov/?term=%22mechano+growth+factor%22+human"}]},{"outcome":"MGF expression after exercise (the body's own)","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"Several small physiology studies","evidence":"Human muscle raises MGF messenger RNA after resistance exercise and growth hormone, more in young than old. Real and interesting; it says nothing about injecting a synthetic fragment.","references":[{"citation":"Hameed M, Lange KH, Andersen JL, et al. The effect of recombinant human growth hormone and resistance training on IGF-I mRNA expression in the muscles of elderly men.","where":"J Physiol, 2004","url":"https://pubmed.ncbi.nlm.nih.gov/14565994/"}]},{"outcome":"Safety in humans","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":true,"human_studies":"None","evidence":"Unknown. A long-acting IGF-1-derived peptide would be expected to share IGF-1's concerns, including effects on glucose and on cell proliferation, and none of that has been measured.","references":[]}],"regions":[{"region":"European Union","status":"Unauthorised medicinal product","note":"No marketing authorisation anywhere. Supplying it for human use is an offence under national medicines law."},{"region":"United States","status":"Not approved","note":"Research reagent 'not for human use'; no clinical programme."},{"region":"United Kingdom","status":"Unlicensed medicine","note":"No MHRA licence."},{"region":"Australia","status":"Prescription-only / unapproved","note":"Not on the ARTG; imports are seized."},{"region":"Canada","status":"Not authorised","note":"No Drug Identification Number."},{"region":"Sport (WADA)","status":"Prohibited at all times","note":"Mechano growth factors are named on the Prohibited List under growth factors (S2), in and out of competition."}],"faq":[{"q":"Does PEG-MGF build muscle?","a":"Nobody knows. It has never been given to a human in any study. The rodent injections that drive the claim used the peptide in muscle directly, not a pegylated version in the blood."},{"q":"Is MGF real?","a":"Yes — as something muscle makes after loading. Human studies have measured it for twenty years. That is a fact about physiology, not about a product."},{"q":"Is it legal?","a":"It is not an approved medicine anywhere, and it is explicitly named on the WADA list. Selling it for human use is an offence in the EU and UK."}],"references":[{"cite":"Hameed M, Lange KH, Andersen JL, et al. The effect of recombinant human growth hormone and resistance training on IGF-I mRNA expression in the muscles of elderly men.","where":"J Physiol, 2004","url":"https://pubmed.ncbi.nlm.nih.gov/14565994/","note":"Measures natural MGF expression; nothing administered."},{"cite":"Searches of PubMed and trial registries for administered mechano growth factor or PEG-MGF in humans.","where":"LYO literature search, September 2026","url":"https://pubmed.ncbi.nlm.nih.gov/?term=%22mechano+growth+factor%22+human","note":"No human administration study identified."},{"cite":"Dominikowski A, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.","where":"Front Endocrinol, 2026","url":"https://pubmed.ncbi.nlm.nih.gov/42395176/","note":"Review of the evidence gap across the class."}],"last_reviewed":"2026-09-10","literature_searched_to":"2026-09-10","changelog":[{"date":"2026-09-10","note":"Initial publication. Grade D: no human administration study exists."}],"license":"CC BY 4.0 — cite as “LYO Research” with a link.","methodology":"https://lyoresearch.com/methodology"}