Side-by-side · Research reference
IGF-1 LR3vsMGF
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AAnimal-StrongHUMAN-REVIEWED10/58 cited
BAnimal-StrongHUMAN-REVIEWED14/55 cited
IGF-1 LR3
IGF-1 Analogue · Research
3–10×Potency vs IGF-I
Low IGFBPBinding affinity
ResearchStatus
Research only · SQ typical in animal models
MGF
IGF-1Ec Splice Variant · Muscle-Specific
SQ · Research context only
01Mechanism of Action
Parameter
IGF-1 LR3
MGF
Primary target
IGF-1 receptor (IGF-1R)McTavish 2009
Satellite cells (Pax7+) in skeletal muscleMoore 2018
Pathway
IGF-1R → IRS-1 → PI3K/Akt → Cell proliferation, protein synthesis, anti-apoptosisMuhlbradt 2009
Mechanical stress → IGF-1Ec mRNA upregulation → Local E-domain peptide release → Satellite cell activation
Downstream effect
Enhanced cell proliferation, muscle anabolism, inhibition of apoptosis, increased telomerase activity
Satellite cell proliferation, myoblast differentiation, muscle fiber repair
Feedback intact?
No — exogenous IGF analogue bypasses GH-mediated regulation
—
Origin
Synthetic 83-AA analogue: 13-AA N-terminal extension + Arg substitution at position 3
Alternative splicing of IGF-1 gene (exons 4-6) produces IGF-1Ec precursor; E-domain cleaved post-translationallyArmakolas 2016Vassilakos 2017
Antibody development
—
—
02Dosage Protocols
Parameter
IGF-1 LR3
MGF
Research dose (animal models)
Variable by protocol and species
In vivo murine atherosclerosis studies used sustained delivery.
—
In vitro typical concentration
10–1000 ng/mLThomas 2007
Dose-dependent effects on follicle growth and estradiol production.
—
Half-maximal stimulation
0.6 nM LR3 vs 1.5 nM native IGF-1Price 2004
2.5-fold greater potency in lung fibroblast proliferation.
—
Evidence basis
Animal / in vitro only
Animal models + in vitro only
Human use
Not FDA-approved; no published human trials
—
Synthetic peptide
—
24-amino-acid E-domain sequence
Corresponds to human IGF-1Ec exons 4-6 region.
Rodent cardiac model
—
200 μg/kg via peptide-eluting microstructures
Post-MI injection; improved ejection fraction by 8 weeks.
Acute delivery (mouse MI)
—
Single bolus within 12 hrs post-infarctionShioura 2014
Delayed decompensation; no human protocol established.
Human evidence
—
None — no published clinical trials
All dosing extrapolated from animal models.
Detection in doping
—
Full-length MGF detected via LC-MS in illicit productsThevis 2014
WADA-prohibited since 2005; no therapeutic indication.
03Metabolic / Fat Loss Evidence
Parameter
IGF-1 LR3
MGF
Mechanism
IGF-1R activation → lipolytic signaling; secondary to anabolic effects
—
Direct lipolytic evidence
Minimal — primarily anabolic/anti-apoptotic in literature
—
Atherosclerotic plaque effects
Reduced stenosis and core size in ApoE-KO micevon 2011
Plaque stabilization via vSMC phenotype modulation, not direct fat loss.
—
Human data
None published
—
04Side Effects & Safety
Parameter
IGF-1 LR3
MGF
Hypoglycemia risk
Theoretical — IGF-1 analogues can lower blood glucose
—
Excessive cell proliferation
Mitogenic signaling; theoretical tumor promotion risk
—
Telomerase activation
2–10-fold increase in prostate cancer cells (PC-3, DU-145, LAPC-4)Wetterau 2003
Critically involved in cancer cell immortalization.
—
Oocyte degeneration
Increased oocyte degeneration at high doses (≥1000 ng/mL) in bovine folliclesThomas 2007
—
Unregulated anabolism
Bypasses physiological GH/IGF-1 feedback; no pulsatility control
—
Unknown human safety profile
No published human trials; safety data absent
—
Human safety data
—
None — no clinical trials published
Theoretical IGF-1 axis risk
—
Chronic IGF-1Ec overexpression linked to cancer progression (prostate, colorectal, breast)
Tumor promotion
—
IGF-1Ec overexpressed in osteosarcoma, colorectal polyps with dysplasia, endometrial cancer
Antibody development
—
Unknown — no longitudinal human exposure data
Local injection reaction
—
Presumed similar to other peptides (erythema, induration) — no direct evidence
Dysregulated expression with age
—
Older adults (70+ yrs) show blunted IGF-1Ec response post-exercise vs youngMoore 2018
Absolute Contraindications
IGF-1 LR3
- ·Active malignancy or history of cancer
- ·Not approved for human use
MGF
- ·Active malignancy or history of IGF-1-sensitive cancers (prostate, colorectal, breast, osteosarcoma)
- ·No established therapeutic use — investigational only
Relative Contraindications
IGF-1 LR3
- ·Diabetes or glucose intolerance
- ·Family history of cancer
MGF
- ·Family history of IGF-1-axis malignancies
- ·Use outside research setting
05Administration Protocol
Parameter
IGF-1 LR3
MGF
1. Research use only
IGF-1 LR3 is not FDA-approved for human use. All administration data derives from animal or in vitro studies.
MGF (E-domain peptide) has no approved clinical protocol. All published data derive from animal models or in vitro experiments.
2. Typical research route
Subcutaneous or intraperitoneal injection in animal models. In vitro: added directly to culture medium at concentrations of 10–1000 ng/mL.Thomas 2007
Commercially available MGF corresponds to the 24-amino-acid human E-domain (hEc). Rodent E-domain (Eb) is structurally distinct and not interchangeable.
3. Reconstitution (research)
Lyophilised powder reconstituted in sterile water or buffered saline per manufacturer protocol. Store at 2–8 °C after reconstitution.
Rodent studies used peptide-eluting polymeric microstructures (cardiac) or direct intramuscular injection. Routes and doses non-translatable to humans.Peña 2015Shioura 2014
4. Stability
Enhanced stability vs native IGF-1 due to reduced IGFBP binding; exact half-life in vivo not fully characterized in humans.
MGF peptides prohibited in sport since 2005. Detection via LC-MS established for full-length MGF products.Thevis 2014
5. Research context only
—
Any human use falls outside approved medical practice and regulatory frameworks. No safety or efficacy data exist.
06Stack Synergy
IGF-1 LR3
+ GHRP-6
Multi-pathwayGHRP-6 stimulates endogenous GH release, which drives hepatic IGF-1 synthesis. IGF-1 LR3 provides exogenous, IGFBP-resistant IGF signaling. Combining upstream GH stimulation with downstream IGF receptor activation creates a dual-pathway anabolic effect. However, this bypasses natural feedback and carries compounded mitogenic risk.
- GHRP-6
- 100–200 mcg SQ · 2–3× daily
- IGF-1 LR3
- Research doses variable · post-workout typical in animal models
- Note
- Research context only — no human protocols exist
- Primary benefit
- Theoretical maximal anabolic signaling (GH + IGF axes)
+ Ipamorelin
Multi-pathwayIpamorelin (selective GHRP) stimulates pulsatile GH release without cortisol/prolactin elevation. IGF-1 LR3 directly activates IGF-1R independent of GH. This stack targets both upstream (GH secretion) and downstream (IGF receptor) nodes but eliminates physiological feedback, raising safety concerns around unchecked proliferation.
- Ipamorelin
- 200–300 mcg SQ · evening
- IGF-1 LR3
- Research doses only · timing variable
- Caution
- No human data; animal/in vitro only
- Primary benefit
- Dual-axis anabolic signaling (theoretical)
MGF
+ BPC-157
Multi-pathwayMGF activates satellite cells for muscle fiber repair; BPC-157 promotes angiogenesis, collagen synthesis, and tendon healing via distinct pathways (VEGF, FAK, integrin signaling). Theoretical synergy in post-injury contexts combines myogenic (MGF) and stromal (BPC-157) repair mechanisms. Both lack human validation.
- MGF
- No established dose
- BPC-157
- 250–500 mcg SQ near injury site
- Context
- Animal models only
- Primary benefit
- Theoretical multi-tissue repair (muscle + tendon/ligament)
+ TB-500
ModerateTB-500 (thymosin beta-4 fragment) enhances actin polymerization, cell migration, and angiogenesis—complementary to MGF satellite cell activation. Both upregulated post-injury; combined use presumed additive for muscle regeneration in preclinical models.
- MGF
- No established dose
- TB-500
- 2–5 mg SQ weekly
- Context
- Animal models only
- Primary benefit
- Satellite cell activation + enhanced migration/angiogenesis