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Follistatin or FS-344 is perhaps the new best non-steroidal way to build muscle

Follistatin or FS-344 is perhaps the new best non-steroidal way to build muscle

Follistatin is an inhibitory protein which is found in every tissue type in all higher animals.  Although this discussion will focus on its ability to inhibit myostatin and thus inhibit the inhibition of muscle growth, I have to point out that follistatin does many other things all over your body and to use it just to grow muscle can have grave unforeseen consequences.  One of these other roles is the inhibition of FSH from the pituitary, thus it would participate in rendering a person sterile.


Mechanism Of Action

Follistatin seems to operate by binding to myostatin and inhibiting myostatin binding to the activin IIB receptor. However, In a study done by creating mice without genes for this receptor the results are shocking! The results show that knockout mice for the activin receptor IIB were much more muscular than normal control mice but the follistatin group were significantly more muscular than either the control or activin knockout group.  This shows that follistatin does more than just inhibit the activin receptor IIB. In one example the muscle mass was increased 194%-327%! with 66% increase in muscle cell count and 28% increase in muscle cell size! This shows that although follistatin is a myostatin inhibitor it may be the best non-steroidal mass builder for other reasons.

One hypothesis for why the follistatin group grew more muscle than the ARIIB knockout group was that myostatin is a member of the TGF Beta family. in this family there are cross receptor activation.  Perhaps the follistatin inhibited the binding of other TGF family members to their respective receptors.  This would indicate that myostatin has cousins which do similar things that we have not discovered yet.


The Future

At Ohio State University researchers used a common cold virus to vector the gene amplification of FS-344, the follistatin specific for muscle tissue. The mice that received this shot grew significantly more muscle than other test groups and the control. Additionally the strength of these animals continued to increase till the point of death where all other studied mice of any group grew weaker as they aged.



To increase the follistatin levels in your body may do more harm than good but to increase expression of the FS-344 protein may give you inhuman levels of muscle and strength for the rest of your life.  Perhaps A simpler method of just injecting a small amount into a specific muscle may be the most prudent first step into testing this drug on bodybuilders.  Most of the buzz on the forums declares this a waste of money. I suspect that the black market does not have real FS-344 but something else and that is why people aren’t seeing results.


Nothing in this article or on this site should be considered medical advice or as an endorsement to violate any law of the country in which you reside.  The information given is for fun and entertainment purposes only.  All claims are 100% dependent upon proper diet and exercise.  Please consult a medical practitioner prior to any diet and exercise program.