Follistatin dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Follistatin is a natural protein that blocks myostatin and activin, two brakes on muscle growth. It is studied mostly as gene therapy for muscle wasting diseases.
Evidence grade for Follistatin: Limited. The rule: people have taken it in a published study, but fewer than 100 of them. The sum on this page: 2 completed trials, 12 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 12
- Human studies
- 2
- Found nothing
- 0
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
2 completed trials, 12 people given it
No first-hand reports gathered yet. That is a gap in what we have collected, not a finding that nothing has been reported.
Goal pages: Muscle and strength
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Follistatin is a protein your body makes. It blocks myostatin, a brake on muscle growth. Scientists have tested it by putting the follistatin gene into muscle. Nobody has tested a shot of the protein itself in people. It is not approved for anything.
What people take it for
- Building muscle faster.
- Muscle wasting diseases such as muscular dystrophy.
- Holding on to muscle with age.
What studies in people showed
The studies in people used gene therapy, and they are tiny. Six men with Becker muscular dystrophy had the gene put into their thigh muscles. Four of the six walked 29 to 125 metres further in six minutes afterwards. No harms were reported. Six men with inclusion body myositis, a muscle wasting disease, were also treated. The typical man gained 56 metres a year on the same walk test. Similar men who were not treated lost 26 metres a year. Neither study had a dummy group. In mice, extra follistatin built a lot of muscle, up to about four times normal.
What people report
Reports, not study results
The good
- In the gene therapy studies, most of the treated men walked further.
- No harms were reported in the Becker study.
The bad
- The studies in people used gene therapy, not the peptide sold online. Nobody has tested that in people.
Where these come from: These come from the two small gene therapy studies on this page. We have not collected user reports on this one yet.
My bottom line
The muscle science is real, but it comes from mice and from gene therapy in a dozen sick men. Nobody has shown a vial of follistatin does anything in a healthy lifter. Lift heavy, eat your protein and check your blood work first.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Follistatin has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Getting stronger12 people · 2 studies
Animal and lab work, not yet tested in people
Real results, but from animals or cells, not people. What works in a mouse often does not work the same way in a person. Nobody can patent this, so nobody would ever earn back the cost of a study in people. That is usually why there is none.
- Keeping or building muscle1 animal or lab study
34 of the 36 indexed goals have no study of any kind behind Follistatin
No study in people, animals or cells on this page reports a result for these. That does not prove Follistatin does nothing for them. It does mean anything you have heard about Follistatin and one of these did not come from a study cited here.
Show full evidence
What is Follistatin?
Follistatin is a natural protein that blocks myostatin and activin, two brakes on muscle growth. It is studied mostly as gene therapy for muscle wasting diseases.
Follistatin is a protein the body makes. It grabs and blocks myostatin and activin, two strong brakes on muscle growth.
In people, it has been tested as gene therapy, not as a peptide shot. Doctors put the follistatin gene into muscle using a carrier virus called AAV1. In six men with Becker muscular dystrophy, four walked further in six minutes afterwards. In six people with inclusion body myositis, a muscle wasting disease, the typical person gained 56 metres a year on a six-minute walk. Similar untreated people lost 26 metres a year. Both studies were tiny, and neither had a dummy group.
In mice bred to make extra follistatin, muscle grew a lot. In mice that also lacked myostatin, extra follistatin gave about four times normal muscle. That shows it blocks more than myostatin alone.
How does Follistatin work?
It soaks up myostatin and activin, which normally hold back muscle growth. With those brakes off, muscle fibres grow bigger.
The evidence, in charts
Fig. 1a · how many people
12people, across 2 studies in people cited here
| Study | People | Share |
|---|---|---|
| Molecular Therapy 2015 | 6 | 50% |
| Molecular Therapy 2017 | 6 | 50% |
One study holds 50% of these people, so the total rests more on one study than its size suggests. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
2 of 4 sources here are studies in people. The rest are not.
- Study in people · done in people250%
- Animal study · done in animals250%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 4 different years, 2001 to 2017, counted from the list of sources on this page. The newest source on file is from 2017, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Biologic
- Molecule weight
- ~35,000 Da
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
No amino acid sequence is on file for Follistatin, so none is drawn rather than guessed from a name.
The studies we cite
- Study in people2015A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy
A first small look at gene therapy for a muscle wasting disease, not an answer. Six men with Becker muscular dystrophy had the follistatin gene injected into their thigh muscles. Four of the six walked further in six minutes afterwards, by between 29 and 125 metres. Muscle samples showed less scarring. No harms were reported. Here is the problem. Everybody got the treatment, so there is nothing to compare against, and six people cannot tell you whether this works.
AAV1-delivered FS344 injected into the quadriceps of six patients: four improved six-minute walk distance (29 to 125 m), no adverse effects, reduced fibrosis on biopsy.
- Study in people2017Follistatin gene therapy for sporadic inclusion body myositis improves functional outcomes
Six men with a progressive muscle disease walked further after gene therapy, while untreated men like them got worse. The treated group gained a typical 56 metres a year on a six minute walk. The comparison men lost 26 metres a year. Here is the problem. Nobody was picked by chance for either group, so the men who got the treatment may have differed from the men who did not in ways that explain the gap. Six people is far too few to settle it.
Six treated patients gained a median 56 m/year on six-minute walk versus a 26 m/year decline in matched untreated controls; small, non-randomized.
- Animal study2001Regulation of myostatin activity and muscle growth
In mice bred to make extra follistatin in muscle, muscle mass rose a lot. Follistatin stops myostatin from docking on its receptor.
Follistatin blocks myostatin binding to ActRIIB; transgenic mice overexpressing follistatin in muscle showed dramatic increases in muscle mass.
- Animal study2007Quadrupling muscle mass in mice by targeting TGF-beta signaling pathways
In mice with no myostatin, adding a follistatin gene gave about four times normal muscle. So follistatin also blocks other brakes on muscle, called activins, not just myostatin.
A follistatin transgene in myostatin-null mice produced about four times normal muscle mass, showing follistatin also blocks regulators beyond myostatin (activins).
Common questions
Has Follistatin been tested in people?
Yes. 12 people given it across 2 completed trials cited here, 0 of which found nothing. Follistatin is a natural protein that blocks myostatin and activin, two brakes on muscle growth. It is studied mostly as gene therapy for muscle wasting diseases.
What is the Follistatin dosage?
No human dose established. Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose. 2 completed trials, 12 people given it
Is Follistatin FDA-approved?
Not FDA-approved; investigational (gene therapy)
Does follistatin build muscle in humans?
In animals, blocking myostatin adds muscle. Early gene therapy studies in people are under way. But follistatin is not an approved muscle building treatment, and the evidence in people is early.