SARMs
Andarine (S-4)
A SARM also called S-4, with animal evidence for bone and body-composition effects; those findings do not establish human osteoporosis or physique benefits.
Controlled rat bone study; human efficacy and long-term safety remain unestablished here
Also known as: S-4
Practical use
Evidence interpretation and clinical context
- Check the starting condition
- Preserve the ovariectomy model in any description of the result.
- Name the actual endpoint
- Use bone density or laboratory bone strength when that is what was measured.
- Avoid a human conversion
- The study does not supply a human treatment or performance protocol.
Overview
Andarine was investigated as a nonsteroidal androgen-receptor modulator. One prominent experiment used ovariectomized rats, a model of estrogen loss, to test preservation of bone rather than athletic performance.
Risks and limitations
The rat study cannot establish human visual, endocrine, liver or cardiovascular safety. It also cannot validate a product sold under the S-4 name. An improvement in animal bone measurements is insufficient to define a clinical benefit-risk balance.
How to read this
Bone mineral density, laboratory breaking strength and fractures in people are different outcomes. A study can improve the first two without ever measuring the third.
Research explained
Selective Androgen Receptor Modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats.
Who was studied
120 female rats allocated across sham-operated and ovariectomized groups; the experiment lasted 120 days.
What was found
S-4 preserved several bone-mineral measures and ex vivo bone strength after ovariectomy, while reducing fat mass in the studied groups.
What it cannot establish
The intervention began around experimentally induced hormone loss. It was not a human fracture-prevention trial or a study of healthy trained adults.
Read the original studyRegulatory status
FDA states that SARMs are unapproved drugs, not dietary supplements.
Supporting sourceThe prevention-model limitation
Starting an intervention at ovariectomy examines prevention of experimental deterioration. That differs from treating established osteoporosis years after menopause.
Supporting sourceClaims versus findings
Not demonstrated
Stronger rat bones prove fewer fractures in people.
The experiment assessed bone properties in rats rather than clinical fractures in human participants.
Check the evidenceCommon questions
Does this paper establish a cutting effect in athletes?
No. Its body-composition findings come from the same hormone-deficient rat model.
SourceSources
Regulatory status — primary or official source
Sources checked 2026-10-01.
General education; not a personal treatment plan.