Side-by-side · Research reference

MGFvsRetatrutide

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-StrongHUMAN-REVIEWED14/55 cited

BPhase 2HUMAN-REVIEWED10/41 cited

MGF

IGF-1Ec Splice Variant · Muscle-Specific

IGF-1EcSplice variantArmakolas 2016

24-AASynthetic E-domain

Animal onlyHuman evidence

SQ · Research context only

Retatrutide

Triple-receptor agonist · Phase 3

1–12 mgWeekly doseJastreboff 2023

24.2%Body-weight ↓Jastreboff 2023

~6 daysHalf-life (est)

SQ · Abdomen · Once weekly

01Mechanism of Action

Parameter

MGF

Retatrutide

Primary target

Satellite cells (Pax7+) in skeletal muscleMoore 2018

GLP-1R + GIPR + Glucagon receptor (triple agonism)Jastreboff 2023

Pathway

Mechanical stress → IGF-1Ec mRNA upregulation → Local E-domain peptide release → Satellite cell activation

Triple-receptor activation → ↑insulin (GLP-1+GIP), ↓gastric emptying, ↑lipid handling, ↑energy expenditure (glucagon component)Jastreboff 2023

Downstream effect

Satellite cell proliferation, myoblast differentiation, muscle fiber repair

Maximal weight loss across class. Glucagon component drives lipolysis and energy expenditure beyond GLP-1+GIP aloneJastreboff 2023

Feedback intact?

—

Origin

Alternative splicing of IGF-1 gene (exons 4-6) produces IGF-1Ec precursor; E-domain cleaved post-translationallyArmakolas 2016 Vassilakos 2017

Synthetic peptide engineered for balanced affinity at three incretin / glucagon receptorsJastreboff 2023

Antibody development

—

02Dosage Protocols

Parameter

MGF

Retatrutide

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.

—

Evidence basis

Animal models + in vitro only

Phase 2 trial; Phase 3 ongoingJastreboff 2023

Standard dose

—

12 mg / week (max efficacy)Jastreboff 2023

Phase 2 trial dose. Phase 3 dosing TBD.

Frequency

—

Once weekly

Titration schedule

—

2 mg → 4 mg → 8 mg → 12 mg over 16 weeks

Duration

—

Indefinite for chronic indication (presumed)

Reconstitution

—

Investigational; not commercially available

Timing

—

Any time of day

Half-life

—

~6 days (estimated from class)

04Side Effects & Safety

Parameter

MGF

Retatrutide

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

—

GI symptoms

—

Nausea, vomiting, diarrhea (very common, dose-dependent)Jastreboff 2023

Heart rate

—

↑ resting HR (3–7 bpm at 12 mg)Jastreboff 2023

Glucose handling

—

Glycemic improvement; rare hyperglycemia from glucagon component

Pancreatitis risk

—

Class warning

Thyroid C-cell tumours

—

Class warning (presumed)

Pregnancy / OB

—

Avoid (insufficient data)

Absolute Contraindications

MGF

·Active malignancy or history of IGF-1-sensitive cancers (prostate, colorectal, breast, osteosarcoma)
·No established therapeutic use — investigational only

Retatrutide

·MTC personal or family history (presumed class effect)
·Pregnancy / breastfeeding

Relative Contraindications

MGF

·Family history of IGF-1-axis malignancies
·Use outside research setting

Retatrutide

·Severe gastroparesis
·History of pancreatitis
·Severe cardiovascular disease (HR signal)

05Administration Protocol

Parameter

MGF

Retatrutide

1. No validated protocol

MGF (E-domain peptide) has no approved clinical protocol. All published data derive from animal models or in vitro experiments.

Investigational peptide. Research vials reconstituted with bacteriostatic water per label.

2. Synthetic peptide form

Commercially available MGF corresponds to the 24-amino-acid human E-domain (hEc). Rodent E-domain (Eb) is structurally distinct and not interchangeable.

SQ — abdomen, thigh, or upper arm. Rotate weekly.

3. Animal delivery models

Rodent studies used peptide-eluting polymeric microstructures (cardiac) or direct intramuscular injection. Routes and doses non-translatable to humans.Peña 2015 Shioura 2014

Once weekly, same day.

4. WADA prohibition

MGF peptides prohibited in sport since 2005. Detection via LC-MS established for full-length MGF products.Thevis 2014

Refrigerate 2–8 °C. Light-protected.

5. Research context only

Any human use falls outside approved medical practice and regulatory frameworks. No safety or efficacy data exist.

27–31G, 4–8 mm insulin syringe.

06Stack Synergy

MGF

+ BPC-157

Multi-pathway

View BPC-157 →

MGF 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

Moderate

View TB-500 →

TB-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

Retatrutide

— no documented stacks