IGF-1 LR3 vs Mechano Growth Factor (MGF)
Both trade on IGF-1 biology in muscle, but one is a long-acting laboratory reagent and the other is a load-induced splice variant your own muscle already makes.
Short answer
IGF-1 LR3 and MGF are both graded preclinical / minimal, which leaves little or no controlled human data to choose between them. IGF-1 LR3 is the one sold for muscle growth, while MGF targets muscle growth and recovery. Both are sold gray-market as research chemicals.
IGF-1 LR3
An engineered long-acting IGF-1 with zero human muscle-building trials; the risks (hypoglycemia, the growth-factor/cancer concern, a WADA ban) follow straight from the biology.
Full IGF-1 LR3 evidence reviewMechano Growth Factor (MGF)
IGF-1Ec / PEG-MGF
A real load-induced IGF-1 splice variant in muscle biology, but the injected PEG-MGF product has no controlled human outcome trials.
Full Mechano Growth Factor (MGF) evidence reviewIGF-1 LR3 vs Mechano Growth Factor (MGF): head to head
- FDA status / approved use
IGF-1 LR3
Unapproved research-grade product; prohibited at all times in sport under WADAMechano Growth Factor (MGF)
Unapproved research-grade peptide, not an approved medicine- Marketed for
IGF-1 LR3
Muscle growthMechano Growth Factor (MGF)
Muscle growth, recovery- Outcome areas
IGF-1 LR3
Muscle / strength / lean massMechano Growth Factor (MGF)
Muscle / strength / lean mass; Injury recovery / tissue repair- Evidence grade
IGF-1 LR3
Preclinical / minimalMechano Growth Factor (MGF)
Preclinical / minimal- How it works
IGF-1 LR3
Long-acting IGF-1 analog that evades binding proteins, extending anabolic growth signalingMechano Growth Factor (MGF)
Load-induced IGF-1 variant that pushes muscle satellite cells to multiply- Route and dosing
IGF-1 LR3
Injection; no established human doseMechano Growth Factor (MGF)
Injection, usually as pegylated PEG-MGF; no established dose- Headline human result
IGF-1 LR3
Not establishedMechano Growth Factor (MGF)
Not established- Strongest evidence
IGF-1 LR3
Watts, Int J Epidemiol 2023. Little or no controlled human outcome data for the marketed useIGF-1 LR3 evidence reviewPubMed 35726641Mechano Growth Factor (MGF)
Yang & Goldspink, FEBS Lett 2002. Little or no controlled human outcome data for the marketed useMechano Growth Factor (MGF) evidence reviewPubMed 12095637- Key safety signal
IGF-1 LR3
Hypoglycemia; chronically raising IGF-1 is tied to higher cancer riskMechano Growth Factor (MGF)
No human safety data or established dose; promotes cell growth; vial contents unverified- How it is obtained
IGF-1 LR3
Sold gray-market as a research chemical; no approved or legitimately compounded human productMechano Growth Factor (MGF)
Sold gray-market as a research chemical; no approved or legitimately compounded human product
| IGF-1 LR3 | Mechano Growth Factor (MGF) | |
|---|---|---|
| FDA status / approved use | Unapproved research-grade product; prohibited at all times in sport under WADA | Unapproved research-grade peptide, not an approved medicine |
| Marketed for | Muscle growth | Muscle growth, recovery |
| Outcome areas | Muscle / strength / lean mass | Muscle / strength / lean mass; Injury recovery / tissue repair |
| Evidence grade | Preclinical / minimal | Preclinical / minimal |
| How it works | Long-acting IGF-1 analog that evades binding proteins, extending anabolic growth signaling | Load-induced IGF-1 variant that pushes muscle satellite cells to multiply |
| Route and dosing | Injection; no established human dose | Injection, usually as pegylated PEG-MGF; no established dose |
| Headline human result | Not established | Not established |
| Strongest evidence | Watts, Int J Epidemiol 2023. Little or no controlled human outcome data for the marketed useIGF-1 LR3 evidence reviewPubMed 35726641 | Yang & Goldspink, FEBS Lett 2002. Little or no controlled human outcome data for the marketed useMechano Growth Factor (MGF) evidence reviewPubMed 12095637 |
| Key safety signal | Hypoglycemia; chronically raising IGF-1 is tied to higher cancer risk | No human safety data or established dose; promotes cell growth; vial contents unverified |
| How it is obtained | Sold gray-market as a research chemical; no approved or legitimately compounded human product | Sold gray-market as a research chemical; no approved or legitimately compounded human product |
marks a row where the two differ. “Not established” marks a cell the available evidence does not answer. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
- Preclinical / minimal:
- Evidence is largely animal, in-vitro, or anecdotal. Little or no controlled human outcome data for the marketed use.
Our verdict
Neither injectable is supported for muscle building, and the difference is in what kind of evidence each borrows. IGF-1 LR3 is an engineered analog that resists the IGF-binding proteins and stays active far longer than native IGF-1, with no controlled human trials of any kind for muscle growth and predictable mechanistic risks: hypoglycemia, the IGF-axis cancer concern, and a WADA ban. MGF, formally the IGF-1Ec splice variant, does have real human data, but it is about the body's own gene switching on after resistance exercise, not about injecting anything; the pegylated PEG-MGF product sold online has essentially no human outcome trials, no established dose, and no safety profile. They have not been compared directly, and the honest reading of the MGF literature is that training, not a vial, is what raises your MGF.
IGF-1 LR3 fits if
The LR3 page is the better read for understanding why a sustained, systemic growth-factor signal is the specific thing epidemiology and the Laron data counsel against amplifying.
Mechano Growth Factor (MGF) fits if
The MGF page is the better read for seeing how a genuine satellite-cell mechanism and a real human exercise-physiology finding get quietly swapped in for evidence about an injectable.
IGF-1 LR3 vs Mechano Growth Factor (MGF): common questions
- Is either IGF-1 LR3 or MGF FDA-approved?
- No. IGF-1 LR3 is an unapproved research-grade product; prohibited at all times in sport under WADA. MGF is an unapproved research-grade peptide, not an approved medicine.
- Which has stronger human evidence, IGF-1 LR3 or MGF?
- Neither. Both are graded preclinical / minimal, with little or no controlled human outcome data for the marketed use. The key source for IGF-1 LR3 is Watts, Int J Epidemiol 2023; for MGF, it is Yang & Goldspink, FEBS Lett 2002.
- What are the main safety concerns with IGF-1 LR3 and MGF?
- For IGF-1 LR3, watch for hypoglycemia; chronically raising IGF-1 is tied to higher cancer risk. MGF has no human safety data or established dose; promotes cell growth; vial contents unverified.
Key studies behind each
IGF-1 LR3
- Gellhaus B, Böker KO, Schilling AF, et al. (2023). Therapeutic Consequences of Targeting the IGF-1/PI3K/AKT/FOXO3 Axis in Sarcopenia: A Narrative Review. Cells. PubMed 38132107
- Watts EL, Perez-Cornago A, Fensom GK, et al. (2023). Circulating insulin-like growth factors and risks of overall, aggressive and early-onset prostate cancer: a collaborative analysis of 20 prospective studies and Mendelian randomization analysis. Int J Epidemiol. PubMed 35726641
- Bang P, Polak M, Bossowski A, et al. (2023). Frequency and Predictive Factors of Hypoglycemia in Patients Treated With rhIGF-1: Data From the Eu-IGFD Registry. J Clin Endocrinol Metab. PubMed 37579214
- Laron Z, Werner H. (2021). Laron syndrome - A historical perspective. Rev Endocr Metab Disord. PubMed 32964395
Mechano Growth Factor (MGF)
- Goldspink G. (2005). Mechanical signals, IGF-I gene splicing, and muscle adaptation. Physiology (Bethesda). PubMed 16024511
- Yang SY, Goldspink G. (2002). Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett. PubMed 12095637
- Hameed M, Orrell RW, Cobbold M, Goldspink G, Harridge SD. (2003). Expression of IGF-I splice variants in young and old human skeletal muscle after high resistance exercise. J Physiol. PubMed 12562960
- Ates K, Yang SY, Orrell RW, Sinanan AC, et al. (2007). The IGF-I splice variant MGF increases progenitor cells in ALS, dystrophic, and normal muscle. FEBS Lett. PubMed 17531227
The full evidence reviews
- IGF-1 LR3: a real anabolic hormone, engineered to last — and untested in people
IGF-1 is a genuine anabolic hormone and “Long R3” is engineered to dodge its binding proteins so it lasts far longer. But there are zero human muscle-building trials — and the risks (hypoglycemia, the growth-factor/cancer concern, a WADA ban) follow straight from the biology.
Updated August 2026
- Mechano Growth Factor (MGF): real repair biology, no human proof for the injectable
MGF is IGF-1Ec — a splice variant your muscle makes after loading, and a genuine satellite-cell signal in cell and animal models. But the human data is about your own gene switching on with exercise, not about injecting PEG-MGF, which has no human outcome trials at all.
Updated August 2026
Where to get it
Where to get peptide therapy
Clinician-led telehealth services that prescribe compounded peptides. The specific peptides offered vary by provider — confirm IGF-1 LR3 availability before ordering.
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