Stenabolic

Stenabolic (SR9009) is a synthetic agonist of the nuclear receptors REV-ERBα and REV-ERBβ — two core components of the circadian transcriptional machinery. Unlike SARMs, it has zero affinity for the androgen receptor. It's a circadian-clock drug that happens to reprogram skeletal-muscle and hepatic metabolism as a downstream consequence, which is why the bodybuilding and looksmaxxing community co-opted it as an "exercise mimetic."

REV-ERB Agonism and Circadian Repression#

REV-ERBα/β are transcriptional repressors: when activated, they suppress BMAL1 and the downstream clock-gene network. This collapses the normal oscillatory control of metabolic genes and locks tissues into a pattern that favors fatty-acid oxidation, glucose uptake, and mitochondrial turnover. In mice, pharmacologic REV-ERB activation produced measurable shifts in locomotor rhythms, energy expenditure, and adiposity within days.

"Activation of REV-ERB with synthetic agonists such as SR9009 altered circadian behavior, increased energy expenditure, and reduced fat mass in mice while improving dyslipidemia and hyperglycemia." — Solt, LA et al., Nature (2012)

The practical read-through: the fat-loss and lipid-lowering effects people chase with SR9009 are downstream of circadian repression, not direct lipolysis. This is also why late-evening dosing wrecks sleep — you're directly hitting the clock.

Mitochondrial Biogenesis and Mitophagy in Skeletal Muscle#

The finding that made SR9009 famous: REV-ERBα activation in skeletal muscle simultaneously increases mitochondrial biogenesis and upregulates autophagic clearance of defective mitochondria. The net effect is denser, cleaner mitochondrial pools — the same adaptation endurance training produces, reached pharmacologically.

"REV-ERBα stimulation in skeletal muscle by SR9009 increases mitochondrial biogenesis and mitophagy, resulting in enhanced endurance and a muscle phenotype similar to that induced by exercise training." — Woldt, E et al., Nature Medicine (2013)

In treadmill tests, SR9009-treated mice ran substantially longer before exhaustion. This is the mechanistic basis for the "better wind, higher sustainable HR zones" that experienced users report during cuts — more mitochondria burning more fat per unit of oxygen. Subsequent work confirmed the receptor is genuinely required for exercise adaptation:

"Muscle-specific loss of Rev-erb impairs mitochondrial remodeling and blunts endurance improvements in response to training, reinforcing Rev-erb's critical role in exercise adaptation." — Hu, Z et al., Nature Communications (2025)

Hepatic Lipid and Glucose Handling#

In liver, REV-ERB activation suppresses lipogenic gene programs and downregulates cholesterol and bile-acid synthesis pathways. In rodent models this translates to lower plasma triglycerides, lower total cholesterol, and improved fasting glucose (Solt et al., 2012). This is the rationale users lean on when stacking SR9009 alongside harsh orals to blunt lipid damage — though it should be flagged plainly: this is mechanistic extrapolation from mice, not clinical evidence in humans running AAS. Don't treat it as oral harm-reduction in the way you'd treat a statin or citrus bergamot.

The Off-Target Problem#

Here's the mechanism fact that community writeups tend to skip: a sizeable chunk of SR9009's effects are not actually mediated by REV-ERB. Dierickx and colleagues engineered cells completely lacking both REV-ERBα and REV-ERBβ, then dosed them with SR9009 — and still saw changes in proliferation and metabolism.

"We found that SR9009 affected cellular metabolism and proliferation even in cells completely lacking REV-ERBα and REV-ERBβ, indicating substantial off-target pharmacology." — Dierickx, P et al., PNAS (2019)

Translation: SR9009 is doing something else in addition to REV-ERB agonism, and we don't fully know what. This matters for two reasons. First, the clean "exercise in a capsule" marketing story is oversold — the real pharmacology is messier. Second, the off-target activity includes antiproliferative effects on dividing cells, which is why users with active malignancy should stay away regardless of how quiet the subjective side-effect profile feels.

Why the Short Half-Life Defines the Protocol#

SR9009 is highly lipophilic, poorly soluble, and chewed up on first pass through the liver via multiple phase-I routes (reduction, N-dealkylation, hydroxylation).

"SR9009 exhibits poor oral bioavailability (~2% in rodents) and is rapidly metabolized through multiple hepatic phase-I routes, leading to a short plasma half-life." — Geldof, L et al., International Journal of Molecular Sciences (2016)

Every practical dosing decision flows from this. Oral BA of ~2% means you absorb a fraction of what's on the label, and a 2–4 hour plasma half-life means that fraction is gone by mid-afternoon if you front-loaded. That's why protocols split the daily dose across 3–4 administrations — one pre-training, one mid-day, one late afternoon, with the final dose kept 4+ hours before bed so you don't crush your sleep on the same mechanism you're trying to exploit for fat oxidation. Once-daily dosing is the single most common mistake with this compound, and it's why half the "SR9009 did nothing" reports exist.

Common (most users)#

• Insomnia or disrupted sleep architecture — SR9009 directly modulates the core circadian clock via REV-ERB, so late dosing scrambles sleep onset and depth. Mitigation: keep the final dose at least 4 hours before bed, and front-load the day's splits (pre-breakfast, pre-training, mid-afternoon). If you're running a 4×/day protocol, cap the last dose at lunch.
• Transient fatigue or "flatness" in the first 1–2 weeks, particularly when stacking with cardarine. Usually self-resolves. Mitigation: don't start SR9009 in the same week as a new cut, a new training block, or another new compound — you won't know what's causing what.
• Appetite suppression — mild, welcome on a cut, annoying on a bulk. Mitigation: dose with meals on a bulk; time pre-workout on a cut when the suppression is useful.
• Underwhelming subjective response — by far the most common "side effect" is feeling nothing at all, usually from underdosed or dudded product compounded by the ~2% oral bioavailability. Mitigation: buy from HPLC-tested sources, split the dose 3–4× daily, and don't expect anything dramatic — this compound is a soft add-on, not a headline driver.

Uncommon (dose-dependent or individual)#

• Lipid changes in either direction — rodent data show improved triglycerides and cholesterol, but the off-target pharmacology means you can't predict your own response. Check a lipid panel at baseline and 6–8 weeks in.
• Mood flattening or blunted drive at the upper end of the dose range (30–40 mg/day). If you feel chemically "off," drop to 20 mg/day or discontinue.
• GI upset with oral liquid preparations, usually from the solvent (DMSO, PEG) rather than SR9009 itself. Mitigation: switch vendors or move to capsule form.
• Lingering grogginess if the compound stacks into the evening. Dose audit: where is your last administration, and how close to bedtime?

"SR9009 exhibits poor oral bioavailability (~2% in rodents) and is rapidly metabolized through multiple hepatic phase-I routes, leading to a short plasma half-life." — Geldof et al., IJMS (2016)

Rare but serious#

• Unknown oncological risk. Dierickx et al. demonstrated that SR9009 affects cell proliferation and metabolism independent of REV-ERB receptors — meaning it has substantial off-target activity on dividing cells that no one has characterized in humans. There is no cancer signal either way in human data because there is no human data. Warning sign to stop: any new or changing lump, unexplained weight loss, or persistent lymphadenopathy during a run.

"We found that SR9009 affected cellular metabolism and proliferation even in cells completely lacking REV-ERBα and REV-ERBβ, indicating substantial off-target pharmacology." — Dierickx et al., PNAS (2019)

• Unexplained hepatic or renal markers out of range at the 6–8-week bloodwork. Mechanism for this is speculative, but SR9009 is heavily hepatically metabolized and the off-target profile is broad. Stop if ALT/AST climb >3× ULN or creatinine drifts without an obvious training explanation.
• Severe circadian dysregulation — users who dose aggressively across 24 hours (or around shift work) have reported multi-week insomnia, appetite clock inversion, and mood disruption that persists beyond cessation. Stop and let the clock reset.

Hard contraindications#

• Pregnancy and breastfeeding. Zero reproductive-tox data. Do not use.
• Active malignancy or recent chemotherapy. The REV-ERB–independent effects on cell proliferation are uncharacterized; do not layer an unknown onto an active cancer course.
• Tested athletes. SR9009 is banned year-round by WADA under S4.5 (hormone and metabolic modulators). This is not a grey area.
• Late-evening dosing. Direct circadian-clock modulation. Keep the last dose in the first half of the day.
• Stacking with multiple other unvetted research compounds. SR9009's off-target profile is broad enough that if something goes wrong, you will not be able to attribute it. Run it alone or with well-characterized partners (cardarine, a GLP-1, AAS you already know your response to).

Gender-specific and PCT considerations#

SR9009 is non-hormonal — no androgen-receptor binding, no estrogen interaction, no HPTA suppression. Women can run the same dose range as men with no virilization risk, and no PCT is required for either sex after a cycle. That is the genuine upside of the compound's profile: whatever it does or doesn't do, it isn't leaving you with a hormonal hole to dig out of. The trade-off is that you're paying for that cleanliness with a compound that has zero human trials, meaningful off-target activity, and a pharmacokinetic profile that makes consistent dosing a chore. Bloodwork at baseline and mid-cycle (lipids, CMP, CBC) is the appropriate level of monitoring — not because SR9009 has a known organ-toxicity signal, but because anyone running experimental compounds should be watching their markers anyway.