IGF-1 LR3 vs MGF (Mechano Growth Factor)
Systemic long-acting IGF vs local muscle-repair growth factor
IGF-1 LR3
The growth signal one step downstream of GH, with an extended half-life and a real hypoglycaemia risk. The most directly anabolic peptide a non-medical user can buy, and the one with the most teeth.
Best for
Best when you want a whole-body, long-lasting anabolic IGF-1 signal.
Read full pageMGF (Mechano Growth Factor)
A splice variant of IGF-1 that the body produces locally inside exercising muscle. Used as a post-workout intramuscular shot to amplify the local growth signal in trained tissue only.
Best for
Best when you want a local repair burst around a specific worked or damaged muscle.
Read full pageKey difference
IGF-1 LR3 circulates systemically for hours to days; MGF is a splice variant that acts briefly and locally at the injection site. Systemic-and-long vs local-and-short.
Evidence quality
IGF-1 LR3
Limited human dataPharmacology in healthy adults and in pediatric short-stature trials established that IGF-1 LR3 elevates free IGF-1 levels meaningfully and produces measurable anabolic effects. Long-term safety and efficacy data in healthy adults seeking hypertrophy do not exist. The cancer-promotion concern is grounded in IGF-1's role in tumour biology — it is mechanistic, not just precautionary.
MGF (Mechano Growth Factor)
Preclinical onlyThe endogenous role of the IGF-1Ec splice variant in satellite-cell activation is well established in muscle biology — animal models from the early 2000s mapped the mechanism in detail. Injectable MGF for hypertrophy in healthy adults is supported by small case series and community use, not by completed RCTs. The half-life problem (minutes in circulation) makes traditional clinical trial design awkward, which is part of why the human literature is so thin.
Not sure which one fits? Open both full pages and read the contraindications first — they are usually the deciding factor.