Supplements to Build Strength & Muscle

Recombinant human growth hormone — the classic performance and 'anti-aging' hormone. FDA-approved as a prescription injectable ONLY for growth-hormone deficiency and a handful of other conditions, where replacement reliably improves body composition. But its anti-aging and athletic reputation OUTSTRIPS the evidence: in healthy older adults and athletes, randomized trials and systematic reviews (Liu 2007/2008) show only small body-composition changes, NO functional or strength benefit, and MORE adverse events — edema, arthralgia, carpal tunnel, and impaired glucose tolerance. Distributing or using it for anti-aging or sport is illegal in the US, and it is NOT a dietary supplement. This is a gated harm-reduction reference, not a recommendation.

An orally-active, non-peptide ghrelin mimetic (growth-hormone secretagogue) grouped with the GH-secretagogue peptides. Honest appraisal: real human RCTs show it reliably raises GH and IGF-1 and modestly increases fat-free mass — but the trials that tested whether that translates into real clinical benefit FAILED. It did not improve strength or physical function in healthy elderly, did not slow Alzheimer's (n=563), and the hip-fracture-recovery trial was stopped early for a heart-failure safety signal. It is an investigational drug Merck never brought to market, not a regulated supplement, and it is banned in sport.

An investigational myostatin/activin 'trap' whose only human trial in patients was STOPPED for safety. ACE-031 is a fusion protein of the activin receptor type IIB (ActRIIB) extracellular domain and an IgG1-Fc, engineered by Acceleron Pharma to soak up myostatin and related ligands and thereby release the brake on muscle growth. It has real human data — a single-dose study in healthy postmenopausal women showed a genuine ~3% gain in lean mass — but its phase 2 trial in boys with Duchenne muscular dystrophy was HALTED after the second dosing regimen because of bleeding-related safety signals (nosebleeds/epistaxis and telangiectasias, dilated surface blood vessels). It is NOT an approved drug, development was discontinued, and anything sold grey-market under this name is unregulated. This entry exists to inform, not to recommend.

Insulin is a life-saving prescription hormone for diabetes — and, used illicitly by bodybuilders as an off-label 'anabolic,' one of the most dangerous performance drugs in existence. The theory is nutrient partitioning: insulin drives glucose and amino acids into muscle and suppresses muscle-protein breakdown. But there is NO controlled evidence that insulin builds muscle or improves performance in healthy, non-diabetic athletes — and a non-diabetic who injects it risks profound, sometimes FATAL hypoglycemia (coma, seizures, brain injury, death), plus fat gain. This is a harm-reduction reference documenting a popular, deadly misuse, NOT a recommendation and NOT a dietary supplement.

A myostatin/activin-binding protein with essentially NO human evidence as an injectable supplement — the real human data are from gene-therapy trials that deliver the follistatin GENE, not the grey-market peptide sold online. Follistatin is a naturally occurring protein that binds and neutralizes myostatin and activin, the molecules that restrain muscle growth. In animals, follistatin (or the follistatin gene) produces dramatic, myostatin-knockout-like muscle hypertrophy, and small open-label gene-therapy trials in Becker muscular dystrophy and inclusion-body myositis reported walking-distance gains. But none of that is the same as injecting recombinant follistatin peptide, which has never been tested in a controlled human supplement trial. It is not an approved drug or a regulated supplement, and the grey-market injectable is unregulated. This entry exists to inform, not to recommend.

The pharmaceutical-grade version of IGF-1 — an FDA/EMA-approved prescription injectable, but approved ONLY for a rare childhood growth disorder (severe primary IGF-1 deficiency / Laron syndrome), where it genuinely raises height velocity in clinical trials. It is the regulated counterpart to the grey-market igf-1-lr3 peptide bodybuilders inject, and shares the same core risks. Crucially, there is NO trial supporting its off-label use for muscle, performance, or anti-aging in healthy adults — and IGF-1's documented harms (hypoglycemia, intracranial hypertension, lymphoid/tonsillar hypertrophy, and a theoretical cancer concern because IGF-1 is mitogenic) are real. Not a dietary supplement, not a longevity drug.

A synthetic long-acting analog of growth-hormone-releasing hormone (GHRH), promoted online to raise GH and IGF-1 for muscle, fat loss and 'anti-aging'. Honest appraisal: the only real human data are two small early-phase pharmacokinetic / safety studies from ~2006 that showed it raises GH and IGF-1 for days — they were never followed by efficacy trials in muscle, body composition or aging. There are NO human outcome RCTs. It is not a dietary supplement: it is sold 'for research use only', is injectable, and is banned by WADA. The original DAC version's clinical development was abandoned.

A grey-market injectable 'research peptide' with NO human efficacy trials of the analog itself — the muscle-growth marketing is extrapolated from cell-culture and animal work. IGF-1 LR3 (Long R3 IGF-1) is a synthetic, engineered analog of human IGF-1: three residues are changed and a 13-amino-acid extension is added so it binds the IGF-1 receptor normally but barely binds the IGF-binding proteins that normally regulate native IGF-1. The result is a far longer-acting, less-regulated IGF-1 signal — which is exactly why bodybuilders inject it and exactly why it is concerning. It was created as a laboratory reagent (it drives cell proliferation in culture and organ/myoblast growth in fetal-sheep infusions), not as a medicine. There has never been a published human trial of IGF-1 LR3 for muscle, strength, or anything else. It is not an approved drug or a regulated supplement; it is an unregulated grey-market injectable. Activating the IGF-1 axis carries theoretical cancer-promotion risk (IGF-1 receptors are overexpressed on many tumors), and in animal infusions it suppressed insulin secretion and lowered blood glucose — a real hypoglycemia signal. This entry exists to inform, not to recommend.

An injectable analogue of growth-hormone-releasing hormone (the first 29 amino acids of GHRH) that stimulates the pituitary to release growth hormone. Honest appraisal: this WAS an FDA-approved prescription drug (Geref) with real human trials — for diagnosing GH deficiency and treating GH-deficient children — but it was discontinued commercially. Its current marketing as a compounded 'anti-aging' peptide is off-label and is NOT what those trials validated.

A synthetic ghrelin-receptor (GHS-R1a) agonist that triggers a pulse of growth hormone from the pituitary. Honest appraisal: the human data are short biomarker studies (acute GH/IGF-1 rises and a validated diagnostic GH-stimulation test) — it's approved ONLY in Japan as a diagnostic agent. The injectable/intranasal use sold grey-market for muscle, fat loss, and anti-aging has NO outcome trials, and it's banned in sport by WADA.

A synthetic hexapeptide growth-hormone secretagogue (a ghrelin-receptor / GHS-R1a agonist) promoted online to raise GH and IGF-1 for muscle and 'anti-aging'. Honest appraisal: the real human data are short pharmacokinetic and provocative-test studies showing it transiently raises GH (and cortisol) and triggers strong hunger — it is used clinically mainly as a diagnostic GH/HPA-axis stimulus, not as a treatment. Cardioprotection and tissue-cytoprotection are mostly PRECLINICAL (rat) findings, though a small open-label phase I/II stroke trial (GHRP-6 combined with EGF) reported safety and a functional-recovery signal. There are NO human RCTs for any muscle, fat-loss or anti-aging use. It is not a dietary supplement: it is an injectable 'research use only' chemical and is banned by WADA.

A selective synthetic pentapeptide growth-hormone secretagogue (ghrelin/GHS-R1a agonist) sold for research use only. Honest appraisal: the evidence is mostly animal pharmacology showing it triggers a clean GH pulse; an early human PK/PD study confirmed it does release GH in people, but only as a short biomarker pulse — no human efficacy data exist. Its one real clinical-outcome story — a phase-2 trial as a postoperative-ileus drug — FAILED its endpoint (no significant difference vs placebo), and that clinical development stalled. It is not an approved medicine, not a regulated dietary supplement, and is banned in sport.

A grey-market injectable 'research peptide' with NO human efficacy trials — the muscle-growth marketing is extrapolated from cell-culture and animal work. MGF (mechano growth factor) is not a separate hormone but an alternatively spliced variant of the IGF-1 gene — the IGF-1Ec isoform — that muscle produces transiently after mechanical loading or damage. Its distinctive C-terminal 'E peptide' is thought to help activate satellite (muscle stem) cells and kick off repair before the mature IGF-1 portion takes over. That biology made it interesting to muscle physiologists; grey-market vendors then turned the synthetic E-peptide (often as 'PEG-MGF', a PEGylated longer-lasting version) into an injectable for bodybuilders. There has never been a published human trial of injected MGF for muscle, strength, or recovery. The real evidence is preclinical: in animals, MGF injection into injured muscle reduced fibrosis and inflammation but did NOT improve fiber regeneration; in cells, MGF E-peptide promotes proliferation and shows neuroprotective effects. It is not an approved drug or a regulated supplement; it is an unregulated grey-market injectable. Because MGF is part of the IGF-1 system, activating that axis carries the same theoretical cancer-promotion concerns, and an unsterile injectable adds infection risk. This entry exists to inform, not to recommend.

A synthetic hexapeptide growth-hormone secretagogue (a ghrelin-receptor / GHS-R1a agonist) that triggers a sharp pituitary GH pulse. Honest appraisal: real human studies confirm it acutely raises GH, but the GH response partially DESENSITIZES (attenuates) with continued dosing, it also raises cortisol and prolactin, and there are NO body-composition or clinical outcome trials. A grey-market, research-use-only injectable — not an approved drug or a regulated dietary supplement, and WADA-banned.

The primary male androgen and an FDA-approved prescription drug for diagnosed male hypogonadism — and a Schedule III CONTROLLED SUBSTANCE. For men with genuinely low testosterone, randomized trials show real benefits: the Testosterone Trials (TTrials) improved sexual function, mood, anemia and bone density in older hypogonadal men, and the large TRAVERSE trial found TRT non-inferior to placebo for major cardiac events. But those benefits were modest and indication-specific, NOT a longevity or anti-aging result. It is prescription-only; non-medical, supraphysiologic, and 'anti-aging' use is illegal and carries serious harms — erythrocytosis, suppressed sperm production/fertility, cardiovascular and psychiatric risk. This is a harm-reduction reference, not a recommendation, and testosterone is NOT a dietary supplement.

An investigational monoclonal antibody that blocks the activin type II receptor (ActRII) — the receptor through which myostatin and activin restrain muscle — producing a striking body recomposition (fat DOWN, lean muscle UP) but NO proven functional benefit. In a phase 2 trial in adults with type 2 diabetes and obesity, bimagrumab caused a large loss of fat mass and a real gain in lean mass over 48 weeks, which is why it is now being developed as a metabolic / obesity drug. But the muscle-disease story is a cautionary one: its pivotal phase 2b trial in inclusion-body myositis (RESILIENT) added muscle yet FAILED its primary walking endpoint, and a 2025 systematic review concluded it had no effect on disease progression. It is NOT an approved drug, NOT a dietary supplement, and NOT a longevity drug — gaining muscle on a scan is not the same as moving or living better. This entry exists to inform, not to recommend.

An injectable anabolic-androgenic steroid (AAS) — brand Deca-Durabolin, the long-acting decanoate ester of 19-nortestosterone — and a DEA Schedule III CONTROLLED SUBSTANCE. It has genuine randomized-trial evidence in supervised, catabolic-illness settings: it adds lean body mass and weight in HIV-associated wasting, adds muscle mass and physical function in dialysis patients, and raises hemoglobin in dialysis anemia (a historic FDA-approved indication, since largely replaced by erythropoietin). But it suppresses the hypothalamic-pituitary-gonadal axis — and because it is a long-ester 19-nortestosterone with progestogenic activity, that suppression and the resulting sexual dysfunction ('deca dick') can be prolonged. It worsens the lipid profile (lowers HDL), is associated with cardiac remodelling/cardiomyopathy and premature atherosclerosis in long-term high-dose users, and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding/performance use is illegal without a prescription and carries real cardiovascular, endocrine and sexual harm. Informational, harm-reduction entry only — not a recommendation.

A prescription oral anabolic-androgenic steroid (AAS) — brand Anavar/Oxandrin — and a DEA Schedule III CONTROLLED SUBSTANCE. It has genuine randomized-trial evidence in FDA-approved, supervised muscle-wasting settings: it adds lean body mass, speeds wound healing and shortens hospital stay in severe burns, raises body weight in HIV-associated wasting, and modestly increases adult height in Turner syndrome. But it is 17α-alkylated and hepatotoxic (dose-related transaminase rises, cholestasis, and — with anabolic steroids generally — peliosis and liver tumours), it sharply lowers HDL and raises LDL cholesterol, and it suppresses the hypothalamic-pituitary-testicular axis and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding use is illegal without a prescription and carries real liver, lipid, and endocrine harm. Informational, harm-reduction entry only — not a recommendation.

A 17α-methylated ORAL anabolic-androgenic steroid (brand Halotestin) and a DEA Schedule III controlled substance. Unlike purely veterinary or research steroids, fluoxymesterone DOES have real — if narrow and now largely historical — human prescription indications: androgen replacement in hypogonadal men, delayed puberty in boys, and palliative treatment of androgen-responsive metastatic breast cancer in women, with older use in hereditary angioedema. So there IS some genuine human clinical literature, including a randomized breast-cancer trial and case series. But it is notoriously HEPATOTOXIC: because it is 17α-alkylated, it causes cholestatic jaundice, peliosis hepatis (blood-filled liver cavities, sometimes fatal), and is linked to hepatic adenoma/carcinoma. It is strongly androgenic and virilizing, suppresses the hypothalamic-pituitary-testicular axis, and severely worsens lipids. Illicit bodybuilding use is for pre-contest strength and aggression. This is NOT a dietary supplement and NOT a longevity or performance drug this library endorses — informational, harm-reduction entry only, gated out of recommendations. The score sits low: real but narrow legacy indications cannot offset heavy hepatotoxicity and the absence of any healthy-population benefit.

A VETERINARY anabolic-androgenic steroid — trenbolone (acetate/enanthate, brands Finaplix/Revalor) — used only as a cattle growth promoter, NOT in humans, and a DEA Schedule III controlled substance. There are ZERO human efficacy trials and no human approval: the evidence base is animal toxicology, environmental endocrine-disruptor work on trenbolone as a feedlot/aquatic contaminant, and forensic residue/anti-doping detection — none of which shows a human benefit. A 19-nor (nandrolone-derived) steroid, trenbolone does NOT aromatize to estrogen but is highly androgenic and a strong progesterone-receptor agonist. In animals it causes potent HPTA/testosterone suppression with testicular damage and impaired fertility, and its metabolites (17β- and 17α-trenbolone) are documented aquatic endocrine disruptors that masculinize female fish at nanogram-per-litre levels. Illicit human users report severe HPTA shutdown, aggression, night sweats, insomnia, 'tren cough', severely worsened lipids, kidney strain, and progestin-driven prolactin effects/gynecomastia. It is NOT a dietary supplement, NOT a longevity drug, and illegal to possess or use without authorization. Informational, harm-reduction entry only — not a recommendation, and there is no legitimate human use to recommend.

A potent prescription ORAL anabolic-androgenic steroid (AAS) — brand Anadrol/Anapolon — and a DEA Schedule III CONTROLLED SUBSTANCE. It is FDA-approved for certain anemias, and it has real randomized-trial evidence in supervised muscle-wasting settings: it adds body weight and lean/body cell mass in HIV-associated wasting, raises lean mass and strength in older men, and increases haemoglobin and muscle mass in dialysis patients; a Cochrane review found it raises haemoglobin in the anaemia of chronic kidney disease. But it is 17α-alkylated and markedly HEPATOTOXIC — the dominant, headline harm: dose-related transaminase elevations in 27–43% of patients in the HIV trial, and (for anabolic steroids generally) cholestasis, peliosis hepatis with fatal liver rupture, and hepatic adenoma/carcinoma. It also sharply lowers HDL and raises LDL cholesterol, suppresses the hypothalamic-pituitary-testicular axis, and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding use is illegal without a prescription and carries those liver, lipid, and endocrine harms unmonitored. Informational, harm-reduction entry only — not a recommendation.

A VETERINARY anabolic-androgenic steroid — boldenone undecylenate, brand Equipoise ('EQ') — licensed for horses, NOT humans, and a DEA Schedule III controlled substance. There are ZERO human efficacy trials and no human approval: the entire evidence base is animal toxicology, livestock growth-promoter studies, and forensic residue/anti-doping detection work, none of which shows a human benefit. What that animal literature does show is harm: testicular degeneration and androgen-receptor down-regulation with suppressed LH/FSH/testosterone, liver and kidney oxidative damage, cardiac toxicity, and a rise in red-cell mass — and because boldenone aromatizes to estrogen, illicit users report gynecomastia on top of the shared AAS harms (HPTA suppression, adverse lipids, virilization). It is NOT a dietary supplement, NOT a longevity drug, and illegal to possess or use without authorization. Informational, harm-reduction entry only — not a recommendation, and there is no legitimate human use to recommend.

An injectable DHT-derived anabolic-androgenic steroid (Masteron/Masteril) — chemically 2α-methyl-dihydrotestosterone propionate, so it is NON-AROMATIZABLE and behaves as a weak anti-estrogen. Its only real human evidence is historical and obsolete: in the 1960s-70s it was an approved palliative hormonal therapy for advanced/metastatic breast cancer (response rates roughly 35-45% in older comparative trials), where it was eventually displaced by tamoxifen and aromatase inhibitors and withdrawn. There are NO modern human trials for the bodybuilding 'cutting'/'hardening' use it is now sought for — that use is entirely off-label and unsupported. As a 5α-reduced DHT derivative it drives androgenic harm (male-pattern hair loss, prostate stimulation, virilization in women), worsens lipids, and suppresses the HPTA. It is a DEA Schedule III controlled substance, NOT a dietary supplement and NOT a longevity drug. Informational, harm-reduction entry only — not a recommendation.

A 17α-methylated ORAL anabolic-androgenic steroid — methyldrostanolone — that was sold from around 2005 as the illicitly-marketed designer 'prohormone' supplement Superdrol before being banned and scheduled. It has NO legitimate human therapeutic use, NO human efficacy trials, and is a DEA Schedule III controlled substance (placed there under the Designer Anabolic Steroid Control Act of 2014). The honest description of its human evidence base is a string of CASE REPORTS of severe drug-induced liver injury — cholestatic hepatitis and jaundice, sometimes with renal failure — in young men who took Superdrol, alongside forensic/analytical detection and a few animal and in-vitro pharmacology studies. The 17α-methyl group that lets it survive oral dosing is exactly what makes it hepatotoxic. Documented harms are severe: cholestatic liver injury that can WORSEN after stopping, severe HDL/lipid suppression, suppression of the hypothalamic-pituitary-testicular axis, renal injury (including bile-cast nephropathy secondary to liver failure) and hypertension. It is NOT a dietary supplement, NOT a longevity drug, and there is no benefit this library endorses — informational, harm-reduction entry only.

A non-steroidal SARM (enobosarm / MK-2866) developed for muscle wasting and cancer cachexia. Real, large randomized trials show it genuinely adds lean body mass — but it has NEVER been approved: the pivotal cancer-cachexia program met its lean-mass endpoints while missing physical-function endpoints, so a durable functional benefit is unproven. Sold widely as a grey-market 'body-recomp' research chemical, it carries documented drug-induced liver injury, HDL/lipid suppression, and testosterone (HPTA) suppression, is banned by WADA, and the products sold online are frequently mislabelled. Real anabolic signal, unproven function, real harms.

A prescription oral anabolic-androgenic steroid (AAS) — brand Winstrol — and a DEA Schedule III CONTROLLED SUBSTANCE. Its one approved indication is prophylaxis of hereditary angioedema (HAE), where decades of cohort and systematic-review evidence confirm it reduces attack frequency. But it is 17α-alkylated and hepatotoxic (cholestasis, and — for AAS as a class — peliosis and liver tumours), and it causes one of the most DRAMATIC HDL crashes of any drug studied — a classic crossover trial measured a 33% fall in HDL, a 71% fall in HDL2, and a 29% rise in LDL. It also suppresses the HPTA and virilizes. It is NOT a dietary supplement and NOT a longevity drug; non-medical bodybuilding ('cutting') use is illegal without a prescription and unmonitored. Informational, harm-reduction entry only — not a recommendation.

The original oral anabolic-androgenic steroid (AAS) — Dianabol / metandienone, synthesised by John Ziegler for US weightlifters in the late 1950s — and the archetypal bulking steroid of mid-century Olympic doping. It is 17α-alkylated (so it survives oral dosing) and strongly estrogenic. Its FDA approval was WITHDRAWN and it is now a DEA Schedule III CONTROLLED SUBSTANCE with no legitimate medical use; it survives only as an illicit bodybuilding drug. There is genuine older controlled evidence that 100 mg/day adds body weight, total body potassium/nitrogen and lean mass in training men (the Hervey crossover trials) — it really was a working 'performance' steroid. But that benefit comes with the defining harms: it is hepatotoxic (cholestasis, peliosis hepatis, liver tumours for AAS as a class), strongly estrogenic (gynecomastia and water retention from aromatization), it crushes HDL and raises LDL cholesterol, and it suppresses the hypothalamic-pituitary-testicular axis. It is NOT a dietary supplement, NOT a longevity drug, and has no approved indication at all. Informational, harm-reduction entry only — not a recommendation.

A mild anabolic-androgenic steroid (AAS) — brand Primobolan — sold as an injectable enanthate ester (Primobolan Depot) and an oral acetate tablet, and a DEA Schedule III CONTROLLED SUBSTANCE. It is a derivative of dihydrotestosterone (DHT), so it is non-aromatizable (cannot convert to estradiol) and only weakly androgenic and weakly anabolic relative to testosterone. Its real clinical history is OLD and THIN: it was used decades ago to raise hemoglobin in bone-marrow-failure anemias (myelofibrosis, aplastic anemia, MDS) and, historically, as a palliative hormonal agent in advanced breast cancer — evidence that is mostly retrospective series and case reports, not modern RCTs. Off-label it is used in bodybuilding for lean-mass retention while dieting. The honest counterweight: it is NOT a dietary supplement and NOT a longevity drug; non-medical use is illegal without a prescription; the oral acetate form is 17α-methylated and carries hepatic risk while the injectable enanthate is not; and as an AAS it still suppresses the hypothalamic-pituitary-testicular axis, shifts lipids unfavourably, and can virilize. Informational, harm-reduction entry only — not a recommendation.

A nonsteroidal SARM with one small Phase-1 human RCT that did show dose-dependent lean-mass gain over 21 days — but at the cost of suppressed testosterone and HDL cholesterol even at low doses. It was never approved as a medicine, multiple case reports tie it to cholestatic liver injury, internet 'SARM' products are routinely mislabelled, and it is banned by the World Anti-Doping Agency. Sold only as an unregulated grey-market research chemical for body composition.

An unapproved selective androgen receptor modulator (SARM) sold grey-market for muscle and body composition. Its anabolic and anti-cancer data are preclinical (cells/animals); the only human studies are a Phase-1 breast-cancer safety trial and case reports of severe liver injury. WADA-banned, suppresses natural testosterone, and grey-market products are routinely mislabeled.

An early nonsteroidal SARM (S-4 / GTx-007) that was studied preclinically for muscle and bone but NEVER advanced to approval. There are NO human efficacy trials — the anabolic results are from castrated and ovariectomized rats (Gao 2005, Kearbey 2007). It is best known for a distinctive, reversible visual side effect (yellow-tinted vision and impaired night/dark adaptation), it suppresses the body's own testosterone axis, it is banned by the World Anti-Doping Agency, and it is sold only as an unregulated, frequently-mislabeled grey-market research chemical. The honest summary is preclinical-only with real trade-offs.

An oral 17α-alkylated anabolic-androgenic steroid (AAS) — 'Oral Turinabol', developed by Jenapharm in the 1960s — and a DEA Schedule III CONTROLLED SUBSTANCE. It is most notable as the central drug of the state-sponsored doping program of the former German Democratic Republic (East Germany), which administered androgens to several thousand athletes a year, including minors and women, often without their knowledge or consent. There are NO legitimate modern efficacy trials: the substantial human record is the documented harm of that coercive program (irreversible virilization in women and girls, hepatic injury, cardiovascular events, and psychological damage) plus anti-doping detection/pharmacology work. It is 17α-alkylated and hepatotoxic, suppresses the hypothalamic-pituitary-testicular axis, and virilizes. It is NOT a dietary supplement, NOT a longevity drug, and non-medical use is illegal without a prescription. Informational, harm-reduction entry only — not a recommendation.

A high-potency oral SARM with ZERO human efficacy data — its only published animal work was as a reversible male contraceptive in rats, where it built muscle and bone while shutting down the HPTA and suppressing sperm to infertility. Sold grey-market for body composition, it is NOT an approved drug or a lawful supplement, products are frequently mislabeled, and it is banned by WADA. The human literature is limited to anti-doping detection, not benefit. This entry exists to inform, not to recommend.

A synthetic steroidal SARM sold grey-market for muscle growth on the claim that it 'inhibits myostatin.' That claim rests entirely on a single cell-culture study where YK-11 induced follistatin in mouse myoblasts — there are NO animal efficacy trials and NO human data of any kind. It is a research chemical, not a supplement: unapproved, WADA-banned, frequently mislabeled, and suspected of liver toxicity by analogy to other SARMs.

A long-acting beta-2 adrenergic agonist used illicitly for fat loss / 'cutting' and as a livestock repartitioning agent — it is NOT a dietary supplement and is not approved for human use in the US (it is a veterinary drug, and an asthma medicine in a few countries). The 'fat-burner' reputation rests entirely on ANIMAL repartitioning studies (more lean mass, less fat in pigs and cattle); there is no human fat-loss RCT. The real human record is the harm: poisoning outbreaks from clenbuterol-tainted meat and recreational-overdose case series with tachycardia, severe hypokalemia, arrhythmia, and myocardial injury, plus cardiac hypertrophy in animals. It is WADA-banned. The cardiac toxicity, not the fat loss, is the story.