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Follistatin 344

Also known as

FST-344 · FS-344 · FS344 · FST344 · Follistatin-344 · Follistatin · FST-344 (precursor → FS-315) · FS344 / FS315 isoform family · AAV1-FS344 (gene-therapy context) · recombinant follistatin (research peptide)

Community talk. May be wrong. Not medical advice. Not a protocol. Not for human or animal use.

Open in the directory ↗
Peptide Some talk Mixed Vial IM / SubQ; AAV IM Growth factors

Mixed and contested.

What people say Follistatin-344 is a precursor isoform associated with the circulating FS-315 form. Gray-market recombinant vials, AAV gene transfer and plasmid products are different modalities whose effects and amounts cannot be converted across one another. Doses people talk about
Training-day IM chartsAbout 50 or 100 mcg before training

Community and protocol-blog charts with rest days off; sometimes split across trained muscles, but not human dose finding or validated local targeting.

Daily SC chartsAbout 100 mcg/day; 100–200 mcg/day for 10–30 days; separate 200–300 and 250 mcg/day upper/table lines

Gray-market community and app/protocol-table figures with unresolved product identity and PK; not an established benefit-risk range or dose-finding result.

Intermittent SC charts100–300 mcg two to three times weekly; separate 500 mcg twice weekly for 4–5 weeks

Community research-protocol, calculator and vendor-chart alternatives, not clinical arms or a progression.

Sparse weight-based charts1.0 / 1.5 / 2.5 mcg/kg/day

Sparse community-practitioner heuristics; at 80 kg these convert to about 80–200 mcg/day. Not trial-derived dose finding.

Aggressive outliersApproximately 1 mg load followed by about 100 mcg bilaterally daily for about 20 days, or 500 mcg bilateral IM plus high rest-day SC totals

Aggressive anecdotal forum outliers with confounding and no validated product identity, safety, or dose finding.

These are preserved community or vendor-chart contexts, not validated human hypertrophy dosing; AAV vector doses are a separate modality and are excluded from this comparison.

Half-life & effect duration

Half-life in the body
  • Community estimate · recombinant proteinAbout 90 minutes
Felt duration people report
  • Early sensationsHunger within 30 minutes in one account; fatigue varies
  • Continued useFullness, vascularity, strength claims or weeks of lethargy
  • Other accountsNo weight change or no effect
Timing context & sources
How it may feel Reports conflict: some describe injection-site pain, fatigue, hunger, fullness or strength change, while others report little or no effect. Product testing and multi-drug co-use make even apparently detailed logs uncertain.
Cycles people discuss The profile preserves incompatible community calendars: short daily subcutaneous runs, training-day intramuscular blocks and less frequent high-amount schedules. None is a validated clinical hypertrophy cycle. Timing No reviewed human PK table was found for a verified gray-market recombinant FST-344 vial. Roughly 90-minute claims remain repeated lore; engineered Fc fusion and AAV expression data concern different products and endpoints. Stacks Growth-hormone-pathway agents, IGF-1 products and anabolic steroids frequently co-occur, so physique changes cannot be assigned to follistatin alone. Watch for Fakes / impure / substituted product: Analytical surveys: only ~9/17 labeled FS products contained follistatin; positives often His-tagged with oligomers; others contained GHRPs/MGF. Null results and weird sides may be wrong molecule.
Related
ACE-031BimagrumabYK-11FLGR-242

Tap a line to jump into the full notes. Research only — may be wrong.

Timing context & sources

Half-life in the body

No human pharmacokinetic range was established for an independently verified gray-market recombinant FST-344 vial.

An engineered FST315-Fc animal paper was designed to prolong exposure, and human AAV1.CMV.FS344 research concerns ongoing gene expression after intramuscular vector delivery. Neither measures the parent protein in a retail vial.

Gray-market product testing found frequent substitution and oligomerized His-tagged material. Isoform, tag, formulation, route, assay and identity are therefore unresolved before any numeric half-life can be transferred.

Felt duration people report

Inspected reports conflict across immediate hunger or fatigue, several-week lethargy, fullness or vascularity, no weight change and no effect.

One French ten-day report claimed three kilograms without body-composition verification plus hunger within 30 minutes and severe fatigue; another user reported hunger without fatigue, and a four-week account reported no weight change with slight water retention, fullness and lethargy. English discussion also included both strength claims and explicit null or fake-product skepticism.

Unverified labeled products, no analytical confirmation, co-use, translation context, self-selected reporting and missing objective measurements prevent a typical onset, duration or prevalence estimate.

  • Think Steroids forum — Follistatin (opens in a new tab)Brief thread includes claims of strength gain and retention alongside repeated skepticism, experimental-product warnings, requests for LC/MS verification and reports of no reliable result.Unverified products and identities, anonymous posts, co-use and no standardized follow-up or measurements.
  • Think Steroids France — Essai de follistatine (opens in a new tab)Same-author posts describe a ten-day subcutaneous product, claimed three-kilogram change without body-composition verification, hunger within 30 minutes and severe fatigue; later replies dispute identity and include hunger without fatigue.Unverified product, translated forum context, self-report, no composition testing and no controlled body-composition measurement. A current independent direct re-fetch was blocked by Incapsula; substantial indexed content was read and the described passages were corroborated.
  • Think Steroids France — Inhibiteurs de myostatine: follistatin, ACVR2B, ACE-031 (opens in a new tab)A four-week FST self-report described no weight change, slight water retention, a fuller or more vascular look and severe lethargy while noting the limited information base.Anonymous unverified product report with subjective appearance and no analytical identity or controlled outcome measurement. A current independent direct re-fetch was blocked by Incapsula; substantial indexed content was read and the described passages were corroborated.

Other context in this card

What people say 14

  • Lean mass / size (peptide logs): Fuller look, scale weight, and “lean tissue” claims over multi-week runs appear in BB forums and biohacker write-ups — heavily confounded by surplus calories, training, AAS, GH peptides, and product authenticity. forum
  • Dramatic early scale claims: Scattered logs describe multi-pound gains in 1–3 weeks (sometimes with flu-like sides); attribution is unreliable and stacks are rarely clean. anecdote
  • Strength / pumps: Some users report overload capacity, pump, and trained-muscle soreness after IM into working muscles; others report zero noticeable effect. anecdote
  • Recomp language: Fat-loss or “dryer leaner” language often rides along with size claims without DEXA-grade methods. forum
  • Longevity / clinic plasmid marketing: Commercial plasmid FST-344 offerings claim lean-mass upticks, fat down, epigenetic-age talk, and multi-month expression after infrequent SC dosing — independent verification and healthy-athlete relevance remain contested; not equivalent to research-peptide cycles. forum
  • Stack confound: Gains frequently co-occur with AAS, insulin, HGH/secretagogues, IGF-1 LR3, YK-11, or hard camps — single-agent credit is weak. forum
  • Null / placebo lore: A large fraction of community posts report no meaningful change; authenticity, short half-life, and overhyped gene-therapy expectations are the usual explanations. forum
  • 2026-09 X log: “I did a follistatin 344 cycle and the only thing i got was PIP.” Null plus injection pain — the classic gray-vial story. anecdote
  • Iron Den 2026 acquaintance rumor: One member said a non-seller looked different at 2 weeks of a planned 4-on/4-off; the board’s first question was fake pics / what else is growing. forum
  • Mice (AAV FS-344): Single gene-delivery of follistatin-344 produced large, lasting skeletal-muscle increases (often cited as among the strongest of several myostatin-pathway inhibitors tested; multi-year durability in some models). animal
  • Nonhuman primates: IM AAV1-FS344 → larger/stronger treated quads over multi-month follow-up; preclinical write-ups emphasize tolerability and no clear reproductive-hormone disruption in those protocols. animal
  • Human gene-therapy hook: Phase 1/2a AAV1.CMV.FS344 in Becker muscular dystrophy (and related sIBM work) reported functional walk-test improvements in early patients without serious adverse events in initial cohorts — disease context, not healthy-athlete proof. trial
  • Broader than myostatin-only: Also neutralizes activins and other TGF-β family ligands in preclinical summaries — part of both efficacy hype and off-target caution. animal
  • mRNA / nanoparticle animal work: SC nanoparticle FS mRNA to liver → hepatic expression → circulating follistatin and ~10% lean-mass edge after multi-week dosing in mice (different delivery class again). animal

Doses people talk about 20

  • Training-day IM low protocol (widely charted): ~50 mcg intramuscular ~30 minutes pre-workout on training days only; rest days off. Often paired with ~8 weeks on / ~8 weeks off in protocol blogs. forum
  • Advanced pre-workout IM band: ~100 mcg IM pre-workout (sometimes split bilaterally into the trained muscle group) on training days. forum
  • Daily SC consensus band: ~100 mcg once daily SC is the most repeated “standard start / working” figure across bodybuilding peptide write-ups. forum
  • Common daily working range: ~100–200 mcg/day SC for roughly 10–30 day blocks, then multi-week off. forum
  • Upper daily community band: ~200–300 mcg/day appears in “advanced” or short aggressive charts; several writers claim little extra above ~200 mcg/day. forum
  • PeptIQ-style table values: Starting ~100 mcg daily SC; “standard” ~250 mcg daily SC also appears in app/protocol tables — still community, not trial dosing. forum
  • Self-report buckets: Small anonymized user samples cluster most often at ~50–100 mcg per injection, with a secondary ~100–200 mcg bucket. forum
  • 2–3× weekly band: Some research-protocol summaries cite ~100–300 mcg SC two to three times weekly instead of true daily. forum
  • High-per-shot / low-frequency alternative: ~500 mcg per injection twice weekly for ~4–5 weeks appears on calculator/protocol pages as a minority schedule. forum
  • Aggressive anecdote extremes (not standards): Forum logs of ~1 mg “load,” then ~100 mcg bilaterally daily for ~20 days; or ~500 mcg IM bilateral pre-workout plus high rest-day SC totals — confounded, expensive, and side-risk heavy. anecdote
  • Weight-based heuristics (sparse): Some practitioner charts list ~1.0 / 1.5 / 2.5 mcg/kg/day bands (e.g., 80 kg → ~80–200 mcg) but most people default to flat 100 mcg. Not trial-derived. forum
  • Timing debates: (1) ~30 min pre-workout IM training days; (2) post-workout SC with food; (3) morning daily SC; (4) AM/PM split of daily total — no head-to-head PK winner published for gray-market vials. forum
  • Route fight: IM-into-target-muscle camp vs systemic SC camp. IM lore chases local hypertrophy and training-window timing; SC lore treats short half-life + circulating FS-315 as whole-body. Many serious logs still use SC for convenience. forum
  • Plasmid clinic products: Marketed as infrequent SC administrations with multi-month expression — separate product class from 1 mg lyophilized research vials. forum
  • Cost realism: True biotech recombinant human follistatin is historically very expensive per mg; cheap multi-mg “research” vials drive authenticity skepticism. forum
  • Scarce / ~$100 per vial (2026 Iron Den): Board said it “picked up steam June–July” then got hard to find. Price is not a COA. forum
  • Do not paste FLGR milligrams or Jay’s 20-day 100 mcg quarterly onto a 1 mg lyophilized research vial. That mix-up is on a live 2026 BB thread. forum
  • Gene therapy ≠ mcg chart: AAV1-FS344 clinical work used vector-genome doses (order of 10^11–10^12 vg/kg class IM multi-site quads in BMD protocols) — cannot be converted to research-vial mcg. trial
  • Framing: Community and vendor-chart research ranges only — not medical advice, not clinical prescriptions, not validated athletic protocols. No human RCT has established a hypertrophy dose for injectable recombinant FS-344. forum
  • Quality / identity risk: Black-market testing (e.g., Reichel et al. class work) found only a subset of labeled “FS344/FS315” products actually contained follistatin; positives were often His-tagged with oligomers; some fakes carried MGF or GHRP-2 instead. trial

How it may feel 9

  • Injection day 0: Usually no systemic “buzz.” IM into trained muscle can produce sharp local soreness (some logs describe hobbling after leg IM). SC more often mild site irritation. forum
  • Hours post-dose: No well-validated acute performance high; pre-workout timing is habit/window lore, not proven peak-plasma data for gray-market vials. forum
  • Days 1–3: Little cosmetic change expected. Tagged / impure product lore includes flu-like malaise; fatigue and site pain are the main early complaints. forum
  • Weeks 1–2: Some claim fuller look, recovery noise, or pumps — still early for true myofibrillar hypertrophy attribution. Non-responders already common. forum
  • Weeks 2–3: Anecdotal “lean mass week” window in aggressive logs (sometimes with other PEDs); reassess authenticity if zero signal. anecdote
  • Weeks 3–4: Common checkpoint for weight, measurements, strength feel, and joint/tendon comfort under heavier loading. forum
  • Weeks 4–8: End of many community “on” blocks (especially 6–8 week training-day IM charts or extended daily SC runs). Results mixed; tendon-adaptation lag talk rises if loads climbed fast. forum
  • Short-cycle camps (10–30 days): Many daily-SC charts end here with a multi-week off before any re-run. forum
  • PIP-only cycle talk (2026-09): Current social-media log with no cosmetic change claimed — pain without the screenshot. anecdote

Cycles people discuss 11

  • Short daily-SC camp (very common in write-ups): ~10–14 days conservative first look; ~20–30 days standard “on,” then ~3–4 weeks off before any re-run. Rationale lore: let myostatin/follistatin axis re-equilibrate and watch for delayed sides. forum
  • Advanced short high-dose: ~10–20 days at ~200–300 mcg/day then ≥4 weeks off appears in some tables. forum
  • Training-day IM camp: ~6–8 weeks “on” of pre-workout IM (training days only), often mirrored by ~8 weeks off (e.g., 8/8). forum
  • Twice-weekly high-shot camp: ~4–5 weeks at high mcg per injection, then break — minority schedule. forum
  • Longevity-style peptide speculation: Lower ~50–100 mcg, ~10–14 days, a few times per year with long offs — explicitly speculative and often confused with gene-therapy data. forum
  • Pulsing: Rest-day skips when protocol is pre-workout IM only; daily SC charts usually dose every day of the short block. forum
  • Re-runs: Seasonal bulk restarts appear; no multi-year gray-market safety registry. forum
  • Continuous open-ended use: Generally discouraged in cautious threads (axis disruption, cost, authenticity, unknown chronic TGF-β-family sequestration). forum
  • Exit flags discussed: Visual changes (CSCR-class worry after extreme doses), severe flu-like illness, progressive unexplained symptoms, fertility red flags, or zero benefit with verified product — community stop talk, not a medical algorithm. forum
  • 4 on / 4 off showed up on Iron Den as one acquaintance’s 2026 plan. Minority next to the usual 10–30 day SC camps. forum
  • Gene contrast: Vector/plasmid work = single or infrequent administration with prolonged expression — not multi-week peptide cycling. trial

Timing 9

  • PK gap: Clear published human pharmacokinetic tables for gray-market lyophilized FST-344 injectables are sparse to absent. forum
  • ~90-minute circulating half-life lore: Widely repeated in peptide blogs and pharmacology critiques of unmodified recombinant follistatin (rapid clearance; poor drug-like candidate vs engineered long-acting analogues). This is the main reason daily or near-daily dosing appears in charts. forum
  • Conflicting site claims: Some app/wiki pages list multi-hour to ~day-scale half-life figures without primary citations — treat as unverified marketing/PK noise next to the short-HL consensus. forum
  • Why frequent dosing (peptide): Assumed short coverage → daily SC or training-day IM during hypertrophy blocks; twice-weekly high-dose is the outlier workaround. forum
  • Pre-workout ~30 min timing: Habit and training-window storytelling, not validated Tmax data for research vials. forum
  • Post-workout SC timing: Aligns dose with elevated protein synthesis / food — preference lore. forum
  • Plasmid marketing duration: Some clinic products claim non-heritable effects lasting on the order of ~1 year per course — different modality. forum
  • Gene-therapy durability: Lasting muscle size comes from ongoing local/systemic expression after vector delivery, not from a long half-life of a single injected protein bolus. animal
  • Analogue research note: Academic/industry work continues on engineered follistatin constructs with lower clearance and more myostatin-selective profiles because native-like FS pharmacokinetics are unfavorable. trial

More on what it is 10

  • Why people search it: “Remove the myostatin parking brake” hype — myostatin (GDF-8) caps skeletal muscle mass; neutralizing it is the Belgian-Blue / double-muscle story applied to gray-market peptides and gene-therapy headlines. forum
  • Mechanism (popular): High-affinity binding and sequestration of TGF-β superfamily ligands — especially myostatin (GDF-8) and activins (A/B); also discussed for GDF-11 and related BMPs. Bound ligands cannot activate ActRIIB-class receptors on muscle cells → satellite-cell / hypertrophy talk. forum
  • Critical split: Gene therapy (AAV vector genomes or plasmid constructs that express FS for weeks–months) ≠ multi-week daily mcg shots of lyophilized “Follistatin-344” research peptide. Do not convert vg/kg charts into vial mcg. forum
  • 2026 BB-forum identity mix: Iron Den treated BLL’s long-acting modified product as “FS-344” and quoted Jay’s 100 mcg/day × 20 days quarterly chart. That is not the gray-vial IM/SC mcg culture and is not FLGR milligrams either. forum
  • What it is: Full-length glycoprotein isoform of human follistatin. “344” is the unprocessed amino-acid count; after cleavage of the signal peptide and further processing it yields the main circulating form often called FS-315. A different splice path yields FS-288 (more tissue-bound / gonadal association in textbooks). trial
  • Why 344 specifically in research: FS-344 → mature FS-315 was preferred in AAV muscle gene-delivery programs because circulating FS-315 was argued to have more favorable myostatin vs FSH off-target balance than shorter/tissue-bound isoforms (FS-288 class). trial
  • Evidence honesty: Strongest lasting muscle-size data are animal gene-delivery (mice, nonhuman primates) and early human AAV trials in disease (Becker MD, sIBM) — not large RCTs of gray-market recombinant peptide for healthy bodybuilders. animal
  • What it is not: Not a steroid, not a SARM, not a GH secretagogue, not IGF-1, not FDA-approved for bodybuilding, recomp, or “anti-aging,” and not the same as oral “follistatin” food-supplement marketing. trial
  • Regulatory / sport: Research-only / gray-market for physique talk. WADA S4 (hormone and metabolic modulators) lists agents preventing ActRIIB activation including myostatin-binding proteins such as follistatin — prohibited for tested athletes; detection methods for black-market FS344 (often His-tagged) exist. trial
  • 2026-08 gene-therapy preprint is not a vial: Sequential VEGF-A165 plasmid then AAV9-FST344 in mice reported more mass and more vessels than AAV-FST alone. Animal gene delivery. animal

Stacks 11

  • GH-axis stack: FS-344 + CJC-1295 (DAC or no-DAC) / Ipamorelin — “myostatin brake off + GH/IGF-1 drive.” No clinical combo data. forum
  • Direct IGF stack: FS-344 + IGF-1 LR3 (sometimes DES/PEG-MGF talk) — dual growth-pathway lore; hypo and organ-growth cautions from the IGF side dominate risk talk. forum
  • HGH / Tesamorelin: Advanced bulk logs sometimes pair recombinant GH or Tesamorelin with myostatin-class agents — heavy confound. forum
  • Connective-tissue buffer: FS-344 + BPC-157 + TB-500/TB-4 (“Wolverine-adjacent”) during aggressive loading — rationale is tendon/ligament lag if muscle strength jumps faster than connective tissue. forum
  • AAS / PED base: Often layered onto testosterone or full cycles in advanced BB forums — results cannot be credited to follistatin alone. forum
  • SARM / YK-11 myostatin class: YK-11 is discussed as an oral agent that may upregulate endogenous follistatin in vitro; stacks with injectable FS-344 or epicatechin appear in “Operation Follistatin”-style experiments. forum
  • Epicatechin: Natural-myostatin/follistatin pathway supplement talk; often cheap “base” next to expensive FS vials in YouTube/log experiments. forum
  • MK-677: Oral GH secretagogue paired for recovery/appetite/IGF-1 tone during FS blocks. forum
  • Basics still get credit: Progressive overload, surplus protein/calories, and sleep are repeatedly named when results look real. forum
  • Stack sequencing lore: Some guides suggest running FS alone for a first short block before adding partners — so sides and non-response are easier to attribute. forum
  • Vs ACE-031 / ActRIIB decoys: Comparison stacks more than co-administration — ACE-031 had clinical lean-mass signals but vascular AEs (nosebleeds, telangiectasia) halted development; FS is positioned as ligand trap vs receptor decoy. trial

Storage notes 2

  • No mix instructions here: STUDresearch does not list reconstitution, diluent volumes, or syringe unit charts. People reconstitute many different ways and vial labels differ — that content creates more confusion than clarity. forum
  • Storage (general talk only): Unopened research products are usually kept cool, dry, and away from light per the seller label. Anything after first use is product-specific — follow the label, not a universal forum SOP. forum

Watch for 21

  • Injection site (most common): Redness, swelling, itching, irritation; IM into trained muscle can be disproportionately sore (logs of severe post-leg-IM limp). forum
  • High injection-site pain / solvent issues: Some batches blamed for extreme pain — infection vs carrier vs impurity vs tagged protein debates. anecdote
  • Flu-like / systemic malaise: Especially linked in lore to “His-tagged” or impure black-market FS344; can include fatigue for the first few days. forum
  • Nonspecific: Headache, appetite up or sleep shifts, mild nausea at higher doses, occasional dizziness — minority and nonspecific. forum
  • Joint stiffness: Occasionally reported; also theoretical tendon/ligament lag if strength/size rise faster than connective tissue adaptation (myostatin-pathway animal tendon concerns are discussed). forum
  • Cancer / proliferation debate: Growth-pathway and metastasis theoretical concerns for active or prior malignancy; community and research write-ups flag active cancer as a common exclusion. No quantified gym-user incidence tables. forum
  • LDL / metabolic notes (gene-therapy marketing): Some plasmid-clinic summaries mention modest LDL rises in a subset of patients — different modality and not mapped cleanly onto peptide cycles. forum
  • Blood pressure / cardiovascular: Occasional “monitor if hypertensive” language on protocol sites — sparse hard data for recombinant peptide. forum
  • Tagged vs untagged lore: “Untagged” claimed more effective/cleaner; tagged product linked to flu-like sides and weaker results — community filter, not a controlled trial. forum
  • Legal / access: Research-chemical labeling; not approved for human consumption; clinic gene products occupy a different regulatory and cost tier. forum
  • Common exclusion talk: Active malignancy, pregnancy/breastfeeding, serious autoimmune disease, age <18, uncontrolled reproductive disorders — appear in both trial-style exclusions and community caution lists. forum
  • Heart-growth fear vs “skeletal not cardiac” counter is live on that 2026 Iron Den thread; neither side had a gray-vial echo dataset. forum
  • Practical opt-out: “Most peptide shops dropped it; MOTS-c / YK-11 actually do something for me.” forum
  • r/PharmaPE 2026: “Always sold out because nobody buys it because it’s mainly junk; only viral-vector data looks real.” Harsh, common. forum
  • FSH / HPG / fertility caution: Classical biology — follistatin binds activin and can suppress FSH; theoretical hypogonadal/fertility risk. FS344→FS315 was chosen in gene programs partly to reduce this vs FS288-class tissue binding; primate/early human AAV work reported no clear reproductive-hormone catastrophe, but that does not prove gray-market peptide safety for fertility. trial
  • Off-target TGF-β family ligands: Not myostatin-only — activins, GDF-11, BMPs enter theoretical risk talk (bone, hematopoiesis, broader growth pathways). trial
  • Central serous chorioretinopathy (CSCR) case talk: Case discussion of bodybuilders using very high SC follistatin exposure (order-of-1 mg class extreme dosing in reports) with temporary visual impairment that resolved over months — extreme-dose caution, not a common low-mcg finding. trial
  • Fakes / impure / substituted product: Analytical surveys: only ~9/17 labeled FS products contained follistatin; positives often His-tagged with oligomers; others contained GHRPs/MGF. Null results and weird sides may be wrong molecule. trial
  • Gene ≠ peptide risk transfer: Long-term vector immunogenicity, insertional, and expression risks do not equal short research-peptide exposure — and vice versa for daily systemic protein spikes. trial
  • WADA / testing: Prohibited as myostatin-pathway / ActRIIB-axis agent; anti-doping methods can distinguish exogenous (often His-tagged) FS344 from endogenous follistatin in research settings. trial
  • Never risk-free framing: Sparse controlled human peptide safety + high counterfeit rate + multi-ligand biology = high uncertainty even when individual logs look quiet. forum

Updated: 2026-09-11

Evidence mix Mostly community / anecdote tags Full: every bullet (trial + community). Use Scan for a faster bro-science read.
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