Ipamorelin vs MGF
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Ipamorelin
Ipamorelin is a selective growth hormone secretagogue (GHS) and ghrelin receptor agonist. It stimulates GH release with high selectivity — minimal cortisol or prolactin elevation compared to older GHRPs. Widely used in research protocols for body composition, sleep quality, and recovery.
Full profileMGF
MGF (Mechano Growth Factor) is a splice variant of IGF-1 produced locally in muscle tissue in response to mechanical loading (exercise, especially eccentric loading). Unlike circulating IGF-1 which is produced primarily by the liver, MGF is generated within the muscle itself and acts locally to activate satellite cells (muscle stem cells) — the cells responsible for muscle repair, growth, and adaptation. It is considered the primary local anabolic signal generated by resistance training.
Full profile| Ipamorelin | MGF | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | NNC 26-0161, Ipamorelin acetate | Mechano Growth Factor, IGF-1Ec, Insulin-like Growth Factor splice variant |
| Evidence | Investigational (in trials) | Preclinical only |
| Dosing range | 100mcg–300mcg mcg, 1–3x daily (typically pre-sleep and/or pre-workout) | 100mcg–300mcg mcg, Post-workout (within 30–60 minutes of training), 3–4x weekly |
| Administration | Subcutaneous injection, Intramuscular injection | Intramuscular injection (into worked muscle — critical for local effect), Subcutaneous injection (produces more systemic distribution) |
| Key side effects | Water retention (mild), Tingling / numbness in extremities, Increased appetite, Headache (transient) | Localized muscle swelling at injection site (normal response), Hypoglycemia (less pronounced than IGF-1 DES but present), Very short half-life means side effects are brief, Potential overuse injury if post-workout injection is used consistently without adequate recovery |
| Cited sources | 3 references | 3 references |
Key differences
- Evidence level differs: Ipamorelin is investigational (in trials), while MGF is preclinical only.
- Administration: Ipamorelin — Subcutaneous injection, Intramuscular injection; MGF — Intramuscular injection (into worked muscle — critical for local effect), Subcutaneous injection (produces more systemic distribution).
- Frequency: Ipamorelin is typically 1–3x daily (typically pre-sleep and/or pre-workout); MGF is Post-workout (within 30–60 minutes of training), 3–4x weekly.
How each works
Ipamorelin
Ipamorelin selectively stimulates GH release via the ghrelin receptor (GHS-R1a) without significantly elevating ACTH or cortisol — the feature that distinguishes it from GHRP-6 and GHRP-2 (Raun et al., 1998, in swine/rodent models). Human data are limited: a PK study in 40 volunteers established a ~2-hour half-life (Gobburu et al., 1999), and a Phase 2 trial for postoperative ileus (Beck et al., 2014) failed its primary endpoint. It is not FDA-approved, and claims about body composition or recovery are extrapolated from GH physiology, not human outcome trials.
MGF
MGF is encoded by the IGF-1 gene but produced via alternative splicing that generates a unique 49-amino acid C-terminal E-peptide (Ec peptide). The Ec peptide has distinct biological activity from the IGF-1 domain — it directly activates satellite cell proliferation through a receptor pathway separate from the standard IGF-1R. Studies in rodents show that local MGF injection produces significant muscle hypertrophy in the injected limb without systemic IGF-1 elevation. MGF expression spikes within 30 minutes of resistance exercise and declines over 24–48 hours — aligning precisely with the post-exercise anabolic window.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.