What does Follistatin do?

Follistatin is described as an endogenous protein that can reduce myostatin signaling. The source frames it mainly as a research target for muscle growth, myostatin inhibition, and body composition, with stronger clinical discussion around gene-transfer approaches rather than ordinary peptide injection.

How does Follistatin work?

The source describes follistatin as binding myostatin, also known as GDF-8, and some related activin-family ligands. By holding those ligands away from activin type II receptors, follistatin may reduce signals that normally restrain muscle fiber growth.

Is Follistatin FDA approved?

No. The supplied source lists Follistatin as not FDA approved and describes its current clinical status as investigational gene therapy trials.

What side effects are reported for Follistatin?

Reported effects in the source include muscle soreness, injection-site reactions, flu-like symptoms, a slight LDL cholesterol increase, possible FSH suppression, and product quality concerns in non-regulated contexts. The source also notes that responses may differ by dose, duration, and individual factors.

What typical dose is reported for Follistatin?

The source reports limited community dose information and points to research protocols. It also includes a research row of 100-300 mcg daily by subcutaneous injection with variable protocol duration, but this should be treated as source-reported research context rather than dosing guidance.

This entry is not a peptide · It is included because this compound is commonly discussed alongside peptide research.

Hormonal Clinical Trials - human trials under way

Follistatin

Also known as: FST

At a glance

PeptiGuide dataset · reviewed Aug 2026

What it is

Myostatin-binding protein studied in muscle and body-composition research

Status

Clinical Trials

Evidence level: human studies

Typical dose

100–300mcg

Subcutaneous injection

Researched for

Muscle growth, myostatin inhibition, body composition

Trial progress

PrePreclinical
IPhase I
IIPhase II
IIIPhase III
IVPhase IV
FDAFDA approved

Not applicable - Emerging human evidence with important limitations

Use the tools

In plain language

Endogenous protein discussed for myostatin inhibition and muscle-related research.
Source status is investigational gene therapy trials, with human-trial evidence noted.
Community dosing information is limited; the source points readers toward research protocols.
Researched areas include muscle growth, myostatin inhibition, and body composition.

How it's thought to work

Follistatin is presented as a protein that interacts with myostatin/GDF-8 and related activin-family signals. The source describes this binding as preventing those ligands from engaging activin type II receptors, which may reduce signaling pathways that normally limit skeletal-muscle growth. Because it can affect more than one TGF-beta family ligand, its biological effects may be broader than a myostatin-only blocker.

What the research shows

Where the research stands

The source highlights early human work with AAV1.CMV.FS344 gene transfer delivered into quadriceps muscle in six men with Becker muscular dystrophy. It reports functional improvement on the 6-minute walk test in several participants, mixed individual responses, biopsy findings consistent with less fibrosis and larger or more normalized fibers, and no serious adverse effects in that small study. The same general gene-transfer strategy is also described as having been studied in sporadic inclusion body myositis. Important limitations remain: the cited human evidence is small, open label, locally delivered, and not yet supported by large placebo-controlled trials. The source distinguishes this research from non-study use of injectable follistatin for physique goals, where controlled human evidence is described as essentially absent.

What it shows

✓ Human studies

Emerging human evidence with important limitations

△ Limitations

Study protocols describe research and are not dosing recommendations.

Bottom line: Investigational - Gene therapy trials Not FDA Approved

Typical dosing

CommunityCommunity dataset

Limited community data available

See research protocols

Range: See research dosing

Community-reported information is sparse and points back to research protocols rather than a well-established use pattern.

Research dosing

Study-specific protocolsHuman trials under way - protocols are study-specific

Doses observed in studies

100-300 mcg daily

Research Literature - Observed in studies

Study protocols describe research and are not dosing recommendations.

Duration: Variable protocols
Administration: Subcutaneous injection
Frequency: Daily

Timing & administration

Best time to take

Morning

Once daily

Food recommendation

With or without food

Why this timing?

The source links daily consistency to the goal of steadier exposure while describing follistatin as a myostatin-inhibiting protein.

Possible side effects

Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.

Muscle soreness
Injection site reactions
Flu-like symptoms
Slight LDL cholesterol increase
Potential FSH suppression
Product quality concerns

Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.

Sources

PubMed ClinicalTrials.gov FDA.gov

Frequently asked questions

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Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.

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Educational resource, not medical advice. Talk to your clinician before acting on anything here.

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Follistatin

In plain languageIn plain language

How it's thought to workHow it's thought to work

What the research showsWhat the research shows