Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Ostarine (MK-2866 / Enobosarm) | YK-11 | |
|---|---|---|
| Category | SARMs | SARMs |
| Standard Dose | Research indicates 10-25 mg daily orally for 8-12 weeks. Phase 2 clinical trials used 1-3 mg/day with significant lean mass gains. | Research indicates 5-15 mg daily orally for 6-8 weeks. No human clinical trials exist — all dosing data is anecdotal. |
| Timing | Once daily, morning or evening. Consistent timing. Half-life approximately 24 hours. No food timing requirements. | Split into 2 daily doses (morning and evening) due to presumed short half-life (~6-10 hours based on structural analysis). Consistent timing essential. |
| Cycle Duration | 8-12 week cycles. PCT may be required depending on suppression level and cycle length. | 6-8 week cycles maximum. PCT strongly recommended. Avoid extended use due to unknown long-term safety profile. |
| Evidence Level | moderate_human | theoretical |
Ostarine (enobosarm/GTx-024) is a nonsteroidal selective androgen receptor modulator that binds the androgen receptor with high affinity, inducing a conformational change that recruits coactivator proteins preferentially in muscle and bone tissue over prostate and seminal vesicles. This tissue selectivity arises from differential AR cofactor recruitment and 5-alpha reductase metabolism. Ostarine promotes lean body mass by activating AR-mediated transcription of anabolic genes (MYC, IGF-1) in myocytes while minimizing androgenic effects in reproductive tissues. It has demonstrated dose-dependent increases in lean mass in Phase 2 trials.
Research indicates 10-25 mg daily orally for 8-12 weeks. Phase 2 clinical trials used 1-3 mg/day with significant lean mass gains.
Once daily, morning or evening. Consistent timing. Half-life approximately 24 hours. No food timing requirements.
8-12 week cycles. PCT may be required depending on suppression level and cycle length.
YK-11 is a synthetic steroidal compound classified as a gene-selective partial agonist of the androgen receptor. Uniquely among SARMs, YK-11 does not induce the N/C terminal interaction of the AR required for full transcriptional activation, instead selectively activating a subset of AR-dependent genes. Its primary distinguishing mechanism is potent induction of follistatin expression, which directly antagonizes myostatin — a key negative regulator of skeletal muscle mass. This dual action (partial AR agonism + myostatin inhibition via follistatin) theoretically provides anabolic stimulus beyond what full AR agonists alone can achieve.
Research indicates 5-15 mg daily orally for 6-8 weeks. No human clinical trials exist — all dosing data is anecdotal.
Split into 2 daily doses (morning and evening) due to presumed short half-life (~6-10 hours based on structural analysis). Consistent timing essential.
6-8 week cycles maximum. PCT strongly recommended. Avoid extended use due to unknown long-term safety profile.
Take our free assessment to get personalized recommendations based on your health goals, current stack, and biomarkers.
Get Your Free Protocol →or take the assessment →