Side-by-side · Research reference
Follistatin-344vsMGF
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AHuman-MechanisticHUMAN-REVIEWED4/58 cited
BAnimal-StrongHUMAN-REVIEWED14/55 cited
Follistatin-344
Myostatin/Activin Antagonist · Research Use
15–25%FST/MSTN ratio ↑
344 AACirculating isoform
ResearchPhase status
Research · No approved protocol
MGF
IGF-1Ec Splice Variant · Muscle-Specific
SQ · Research context only
01Mechanism of Action
Parameter
Follistatin-344
MGF
Primary target
Myostatin (MSTN/GDF-8) and Activin A
Satellite cells (Pax7+) in skeletal muscleMoore 2018
Pathway
FST-344 binds MSTN/Activin → prevents ActRIIB receptor engagement → disinhibits muscle anabolism
Mechanical stress → IGF-1Ec mRNA upregulation → Local E-domain peptide release → Satellite cell activation
Downstream effect
Elevated follistatin/myostatin ratio, increased muscle protein synthesis, attenuated muscle atrophy signalingJeong 2026
Satellite cell proliferation, myoblast differentiation, muscle fiber repair
Feedback intact?
Yes — indirect antagonist, preserves endogenous regulation
—
Origin
Endogenous glycoprotein, 344-AA isoform lacking heparin-binding domain (vs FST-315)
Alternative splicing of IGF-1 gene (exons 4-6) produces IGF-1Ec precursor; E-domain cleaved post-translationallyArmakolas 2016Vassilakos 2017
Antibody development
Not documented in available trials (endogenous protein)
—
02Dosage Protocols
Parameter
Follistatin-344
MGF
Clinical protocol
None — no approved dosing regimen
Follistatin-344 measured as endogenous biomarker, not administered exogenously in cited trials.
—
Research context
Endogenous modulation via exercise + nutrition
Resistance training + EAA intake elevated FST/MSTN ratio by 15–25% in 12-week RCT (older women).
—
Evidence basis
Human observational / biomarker studies
Animal models + in vitro only
Half-life
Not established
Circulating isoform; lacks tissue-binding domain of FST-315.
—
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
Follistatin-344
MGF
Primary target
Muscle mass preservation, not direct lipolysis
—
Indirect fat effect
Increased lean mass → elevated resting metabolic rate
Not primary mechanism. Muscle-sparing during deficit.
—
Clinical evidence
Lorcaserin trial (6 mo) showed no MAFI axis changes during fat lossRamirez-Cisneros 2026
Suggests follistatin not primary driver of fat loss in weight-reduction interventions.
—
GLP-1RA studies
Liraglutide (35 days) — no significant MAFI axis modulation despite fat/lean changes
—
04Side Effects & Safety
Parameter
Follistatin-344
MGF
Clinical safety data
None — no human exogenous administration trials in literature
—
Theoretical risks
Excessive myostatin inhibition → muscle overgrowth, impaired glucose tolerance
Based on myostatin-null animal models and clinical myostatin inhibitor trials.
—
Endogenous elevation (exercise)
No adverse effects reported in 12-week resistance + EAA trials
—
Cancer risk (theoretical)
Myostatin inhibition may promote tumor growth in malignancy (preclinical data)
—
Regulatory status
Not approved for human use — research peptide only
—
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
Follistatin-344
- ·Active malignancy
- ·No approved protocol — research use only
MGF
- ·Active malignancy or history of IGF-1-sensitive cancers (prostate, colorectal, breast, osteosarcoma)
- ·No established therapeutic use — investigational only
Relative Contraindications
Follistatin-344
- ·Insulin resistance / Type 2 diabetes (monitor glucose)
- ·Pregnancy / lactation (unknown safety profile)
MGF
- ·Family history of IGF-1-axis malignancies
- ·Use outside research setting
05Administration Protocol
Parameter
Follistatin-344
MGF
1. Regulatory status
Follistatin-344 is not approved for human administration. All cited studies measure endogenous serum follistatin as a biomarker, not as an exogenous therapeutic agent.
MGF (E-domain peptide) has no approved clinical protocol. All published data derive from animal models or in vitro experiments.
2. Endogenous modulation
Resistance exercise combined with essential amino acid (EAA) supplementation elevated the follistatin/myostatin ratio by 15–25% in 12-week randomized trials. Protein intake (1.2–1.5 g/kg/day) synergizes with training to upregulate endogenous follistatin.
Commercially available MGF corresponds to the 24-amino-acid human E-domain (hEc). Rodent E-domain (Eb) is structurally distinct and not interchangeable.
3. Measurement context
Serum follistatin and follistatin/myostatin ratio are used diagnostically in sarcopenia screening and as biomarkers of muscle anabolic balance in clinical trials.
Rodent studies used peptide-eluting polymeric microstructures (cardiac) or direct intramuscular injection. Routes and doses non-translatable to humans.Peña 2015Shioura 2014
4. Research consideration
Gene therapy and recombinant follistatin delivery are under preclinical investigation for muscular dystrophy and sarcopenia. No human safety or efficacy data for exogenous FST-344 administration.
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
Follistatin-344
+ BPC-157
Multi-pathwayFollistatin-344 (myostatin antagonist) and BPC-157 (tissue repair peptide) address complementary pathways in muscle recovery. FST-344 promotes muscle protein synthesis by disinhibiting myostatin signaling, while BPC-157 accelerates healing of tendons, ligaments, and microtears via angiogenesis and collagen synthesis. Combined, they may support both hypertrophy and structural repair during high-volume training or injury recovery.
- Follistatin-344
- No approved protocol — endogenous modulation via resistance exercise + EAA
- BPC-157
- 250–500 mcg SQ · twice daily · near injury site or systemic
- Duration
- 4–8 weeks
- Primary benefit
- Muscle hypertrophy + accelerated soft tissue repair
+ TB-500
ModerateTB-500 (thymosin beta-4 fragment) promotes cell migration, angiogenesis, and anti-inflammatory signaling in muscle and connective tissue. Follistatin-344's anabolic signaling may synergize with TB-500's regenerative effects during muscle damage or overtraining, particularly in older adults where both myostatin inhibition and tissue repair are rate-limiting.
- Follistatin-344
- Endogenous upregulation (resistance training + protein)
- TB-500
- 2–5 mg SQ · twice weekly · loading phase 4 weeks, then maintenance
- Frequency
- Twice weekly TB-500, daily training stimulus for FST
- Primary benefit
- Enhanced recovery, reduced inflammation, muscle growth support
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