SR9009, also called Stenabolic, is a synthetic compound people take in the hope of getting some of the benefits of cardio without doing as much of it: better endurance, easier fat loss, a faster metabolism at rest. It is popular in cutting and endurance circles and usually grouped with Cardarine as an "exercise mimetic." It is not a steroid or a SARM, it does not touch your hormones.
Every benefit attributed to SR9009 comes from studies in mice, there are no human trials at all, and the oral form is barely absorbed. People still anecdotally report endurance and fat-loss effects.
Deep-dive
SR9009 was developed in the lab of Thomas Burris at Scripps and first described in a 2012 Nature paper as a synthetic agonist of REV-ERB, a pair of nuclear receptors (REV-ERBα and REV-ERBβ) that sit inside the circadian clock machinery and act as transcriptional repressors, switching certain genes off. REV-ERB helps set the daily rhythm of metabolism in liver, fat, and skeletal muscle. The idea behind SR9009 is that pharmacologically activating REV-ERB nudges that machinery toward burning fuel rather than storing it.
The endurance finding. The result that built SR9009's reputation came from a 2013 Nature Medicine paper by Woldt and colleagues. Mice lacking REV-ERBα in muscle had fewer mitochondria, worse oxidative function, and reduced running capacity. Going the other way, activating REV-ERBα, either by overexpressing it or by dosing SR9009, increased mitochondrial number and improved exercise capacity, working through the Lkb1-Ampk-Sirt1-Ppargc-1α pathway that drives mitochondrial biogenesis. The often-quoted line that treated animals "get muscle like an athlete who has been training" comes from this work. It is a real, well-conducted study, but it is a mouse study.
The metabolic findings. The original 2012 work showed that chronically dosing REV-ERB agonists in diet-induced obese mice reduced fat mass without changing how much the mice ate, raised energy expenditure by roughly 5%, and improved blood lipids and glucose. Later mouse work has been broadly consistent: a 2025 study found that low-dose SR9009 blunted the weight gain and insulin resistance caused by circadian disruption, and suggested lower doses may carry a better safety margin than the high doses used in earlier experiments. REV-ERB agonism has also shown anti-atherosclerotic and anti-inflammatory effects in mice.
The big caveat: it may not even work through REV-ERB. In 2019 a PNAS paper from Mitchell Lazar's group built a mouse model with both REV-ERBα and REV-ERBβ genetically deleted, then dosed those cells with SR9009. The compound still changed cell viability, metabolism, and gene transcription, in cells that had no REV-ERB at all. The authors' conclusion was blunt: the effects of SR9009 cannot be attributed solely to REV-ERB, and the drug should not be used as a stand-in for REV-ERB activity. This matters because the entire mechanistic story sold to consumers is "SR9009 activates REV-ERB, REV-ERB does these good things." That chain has a broken link. Some of what SR9009 does in a cell is through an unknown mechanism, and "unknown mechanism" is not a reassuring thing to read about a compound you are putting in your body daily. SR9009 also contains a nitrothiophene group, a structural motif flagged as a potential toxicophore.
The bioavailability problem. Even setting mechanism aside, the oral form barely gets into you. Pharmacokinetic work in mice found oral absorption around 2%, and the compound is cleared fast, with a plasma half-life of only a few hours. This is why dosing protocols tell you to split into three or four doses a day, and why some users move to sublingual or injectable forms to get around first-pass metabolism. The mouse studies that produced all the impressive results used injected SR9009, not oral. So even the rodent evidence does not directly transfer to someone swallowing a capsule.
The cancer angle, in both directions. REV-ERB agonists including SR9009 have been studied as potential anticancer agents. A 2018 Nature paper by Sulli and colleagues found SR9009 and SR9011 were selectively lethal to cancer cells and to oncogene-induced senescent cells in mice, by blocking autophagy and de novo lipogenesis, without obvious toxicity to normal tissue. That sounds like a point in favour, but it cuts both ways: a compound potent enough to kill cells by shutting down autophagy is a compound with real biological force, and autophagy is a process healthy cells, including muscle, also rely on. The same 2013 endurance paper noted REV-ERBα loss increased autophagy in muscle; chronic suppression of autophagy is not obviously benign. None of this has been characterised in humans taking SR9009 recreationally.
Women. There is essentially no female-specific human data, because there is no human data at all. The mouse studies were largely conducted in male animals, which is a real limitation worth naming rather than glossing over. Mechanistically, REV-ERB and the circadian clock interact with oestrogen signalling, and circadian biology differs between the sexes, so it is plausible that response differs too, but that is inference, not evidence. There is no basis for a sex-specific dose because there is no validated dose for anyone. A woman considering SR9009 is in exactly the same evidence vacuum as a man, with the added unknown that the limited animal work may not represent her physiology well.
What users actually report. Community reports are genuinely split, more so than for most compounds. Some endurance and physique users describe improved work capacity, longer time before fatigue during cardio, and easier fat loss during a cut, with effects coming on within a couple of weeks. Others, including people using third-party-tested product, report feeling nothing at all across a full bottle despite trying various dosing schedules. The most consistent thread in the negative reports is the bioavailability issue: oral SR9009 underperforming or doing nothing. Where reports are more consistent is on the absence of hormonal side effects and the lack of stimulation, it is not a stimulant and people do not describe a "kick." Treat the positive reports as a real but unreliable signal, and weigh them against the fact that there is no human trial to confirm any of it.
Dosage:
- Typical reported range is 10 to 40 mg per day, with most people landing around 20 to 30 mg. There is no validated human dose, this range comes entirely from community practice, not trials
- Split the daily amount into 3 to 4 smaller doses spread across the day. The half-life is only a few hours, so a single dose does not hold blood levels
- Take doses earlier in the day rather than late evening. SR9009 acts on the circadian clock and late dosing has a clearer rationale for disrupting sleep than helping it
- Oral capsules and powder are poorly absorbed. Sublingual liquid is used to partly bypass first-pass metabolism. Injecting it is something some users do to solve the absorption problem, but injecting a research chemical with no human safety data and known unstable chemistry carries infection and contamination risk on top of everything else, and is not a step to take lightly
- Often stacked with Cardarine for endurance and cutting.
- Cycles of roughly 8 to 12 weeks are common in community use.
- Third-party testing matters more here than almost anywhere else.
Here's what you can expect:
If it works for you, the realistic picture from user reports is improved endurance and work capacity during cardio, and somewhat easier fat loss during a calorie deficit, showing up over the first couple of weeks rather than immediately. It is not a stimulant, there is no acute hit, and it will not change how a single workout feels the way caffeine does. It does not build muscle and it does not affect hormones.
There is a real chance you notice nothing, especially on the oral form. A meaningful share of users, including those using tested product, report no effect across an entire cycle. This is the single most common disappointment with SR9009 and it is consistent with how badly the oral form is absorbed.
Side effects & risks:
- The honest headline risk is the unknown. There are no human trials, so there is no human safety profile, no documented side effect list, no long-term data, and no established safe dose. Everything below is inference from animal work and community reports, not established fact
- No hormonal side effects. SR9009 does not suppress testosterone, aromatise, or affect the HPTA, this is one of the few things that can be stated with reasonable confidence and it is the main reason people pick it over steroids or SARMs
- Reported side effects from community use are generally mild and inconsistent: fatigue or flatness, headaches, mild GI discomfort, and disrupted sleep if dosed late. Because there is no trial data, it is impossible to say how common these actually are or whether they are dose-related
- Mechanistic concerns worth knowing about, even though they are unquantified in humans: SR9009 contains a nitrothiophene group flagged as a potential toxicophore; it suppresses autophagy, a cleanup process healthy cells including muscle depend on; and the 2019 finding that much of its activity is REV-ERB-independent means some of what it does in your body is through a mechanism nobody has identified
- The cancer data is double-edged. REV-ERB agonists kill cancer cells in mice, but that same potency is a reason for caution, not comfort, in a healthy person dosing chronically. Anyone with a current or recent cancer diagnosis should avoid it outright given how directly it interferes with autophagy and lipogenesis
- SR9009 is on the World Anti-Doping Agency prohibited list. Any tested athlete will fail a drug test, metabolites are detectable
Blood markers
Lipid panel (LDL, HDL, triglycerides), baseline before starting and rechecked at the end of a cycle. The proposed benefit in animals is improved blood lipids, so this is the one place you might see an objective signal, and it is worth knowing whether you do.
Fasting glucose and HbA1c, baseline and end of cycle. REV-ERB agonism affects glucose handling in animal studies, and these markers tell you whether anything is actually moving.
Liver enzymes (ALT, AST), baseline and end of cycle. There is no human hepatotoxicity data either way, which is exactly why you want a reference point, the compound contains a flagged structural motif and is metabolised by the liver.
Full blood count and kidney function (creatinine, eGFR), baseline, as general safety markers for any unproven research chemical run for weeks at a time.
Realistically, nobody actually needs SR9009, there is no deficiency it corrects and no human-validated benefit it delivers. The people who should be most rigorous about baseline and follow-up bloodwork are the ones who have already decided to use it anyway: run the panels, compare before and after, and let your own numbers tell you whether it is doing anything or just sitting on a shelf in your bloodstream doing nothing.
SR9009 is an unapproved research chemical, sold for laboratory use only and not as a supplement or medicine, and is banned in sport by WADA.
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