Kisspeptin is sold in gyms as a way to raise testosterone without testosterone. The first half of that is real: in small, well-run trials, the peptide lifts luteinising hormone (LH) within minutes and testosterone within hours. What the pitch leaves out is what happened when a drug company tried to turn it into a medicine. Given continuously, the same signal switched the system off — so reliably that the analogue went into prostate-cancer trials as a castration agent. This page sets out what was measured and in whom; it reports research and gives no usage guidance, per our editorial standards.
What it is
Kisspeptin is a family of peptides made in the hypothalamus. They act on the kisspeptin receptor (KISS1R, once called GPR54) on the neurons that release gonadotropin-releasing hormone (GnRH), which in turn tells the pituitary to release LH and FSH, and LH tells the testes to make testosterone. Kisspeptin-10 is the shortest fragment that keeps full activity at the receptor; kisspeptin-54 is the longer natural form used in most fertility research. The plain-language entry is Peptide Lexicon's kisspeptin page; this page is about the performance question.
That position in the chain matters. Kisspeptin sits one step above gonadorelin (synthetic GnRH) and two steps above hCG, which is why WADA files all three together.
What it does in men, trial by trial
| Study | Who | What was given | What was measured |
|---|---|---|---|
| George 2011, JCEM | Healthy men | IV kisspeptin-10 boluses 0.01–3 µg/kg; infusions | LH 4.1 → 12.4 IU/L at 30 min (1 µg/kg, n = 6); 3 µg/kg gave a smaller rise than 1 µg/kg; 22.5-h infusion, testosterone 16.6 → 24.0 nmol/L (n = 4) |
| George 2013, Clin Endocrinol | 5 men with type 2 diabetes and low testosterone, 7 controls | IV bolus 0.3 µg/kg; 11-h infusion 4 µg/kg/h | LH rose in both groups; testosterone 8.5 → 11.4 nmol/L in four men during the infusion |
| Ullah 2019, Andrologia | Healthy young, middle-aged and older men | Single IV bolus 1 µg/kg | LH rose in every age group; testosterone rose only in the youngest group |
| Yeung 2026, Eur J Endocrinol | 15 healthy men, 12 controls (Imperial College) | Subcutaneous infusions: acute dose-response; continuous 5 days; 8 h a day for 12 days | LH, FSH and testosterone rose acutely; after 5 days continuous, LH and FSH were back to placebo levels (testosterone still raised); the 8-h-on, 16-h-off schedule kept LH up to day 12 |
Two patterns run through all four. The rise is fast and real — it is the reason research groups use the peptide to probe the reproductive axis, in registered studies of delayed puberty, IVF and hypothalamic amenorrhoea. And more is not more: the tripled bolus in 2011 gave less, older men's testes answered less, and a continuous signal lost its effect on the pituitary within days. The 2026 authors' stated goal was to find a schedule that does not desensitise, and their answer was pulses by pump.
What happened when it was held on: TAK-448
Takeda developed TAK-448, a stabilised analogue of kisspeptin-10. In its two phase 1 studies (MacLean 2014, JCEM, PMID 24762108):
- A single injection raised testosterone about 1.3- to 2-fold within 48 hours in men over 50.
- A 14-day continuous infusion above 0.1 mg a day did the opposite: testosterone fell below baseline by 60 hours and reached a sustained below-castration level by day 8.
- In men with prostate cancer, a one-month depot took testosterone below 20 ng/dL in four of five patients at the higher doses, and PSA fell by more than half.
The company's own rat work had shown the same shape — a transient rise, then testosterone "to castrate levels within 3–7 days", faster than leuprolide (Matsui 2014, PMID 24747751).
Takeda did also test the stimulating direction. NCT02381288, a phase 2 trial of TAK-448 in middle-aged and older men with low testosterone, enrolled 17 men and was terminated; the registry gives the reason as "the study did not meet the primary endpoint" (change in average serum testosterone after six weeks). A second Takeda phase 2, in men with hypogonadotropic hypogonadism (NCT02369796, 15 enrolled), is also listed as terminated.
This is the finding the gym pitch omits. The only company to put a kisspeptin agonist into men with low testosterone stopped the trial, and the same molecule, dosed to stay on, became a hormone-suppressing drug.
The muscle question has no data
PubMed, 2026-09-24. kisspeptin[tiab] returns 3,312 records; with clinical-trial or randomised-trial publication types, 61. Restricted to human studies that mention muscle, lean mass or strength: 11 — and none of the 11 measured skeletal-muscle size or strength. They cover airway and vascular smooth muscle, heart muscle in the lab, myasthenia gravis, and male obesity and hormones.
ClinicalTrials.gov, 2026-09-24. An intervention search for kisspeptin returns 36 records. They are fertility, puberty, hypothalamic amenorrhoea, insulin secretion and the two terminated Takeda trials. None has a muscle, strength, body-composition or performance endpoint.
So any claim that kisspeptin builds muscle is an inference: that the testosterone rise these trials produced — from 16.6 to 24.0 nmol/L during a day-long infusion — would, if sustained, add muscle. The trials never sustained it, and when Takeda tried, it could not.
What the dose figures mean, and what they do not
Every human figure above comes from supervised research, most of it by intravenous line or infusion pump: George 2011 used 0.01–3 µg/kg boluses and 1.5–4 µg/kg per hour infusions; the 2026 study used 180 nmol per hour continuously for five days and 150 nmol per hour for eight hours a day over twelve. Kisspeptin-10 weighs about 1,302 g/mol, so 150 nmol an hour for eight hours is roughly 1.6 mg a day delivered as a slow, even stream. Those are descriptions of what was done in a clinical research unit, not a comparison point for a vial. Peptifact's page on the kisspeptin figures that circulate covers the numbers in commerce.
Status in sport and at FDA
- WADA: named in S2.2.1 — testosterone-stimulating peptides in males, alongside chorionic gonadotrophin, LH and gonadorelin — prohibited at all times. The section-by-section map is on WADA status by compound.
- FDA: no kisspeptin drug is approved. Kisspeptin-10 was added to FDA's Category 2 list of bulk substances for compounding on 29 September 2023, the list of substances FDA has identified as presenting significant safety risks, set out on peptide therapy.
How it compares with the neighbours
Kisspeptin, gonadorelin and hCG are the three testosterone-axis peptides lifters meet, and they sit at three rungs of one ladder: kisspeptin acts on the GnRH neuron, gonadorelin is GnRH acting on the pituitary, and hCG mimics LH at the testis. None is an anabolic agent in its own right; each works only as far as the rung below it responds. For the wider question of whether any peptide beats the basics on muscle, the ledger is peptides for muscle growth, and the testosterone question for the one supplement with real data is on creatine and testosterone.
The honest summary
- In healthy men, kisspeptin-10 raises LH within 30 minutes and testosterone within hours — in four small trials.
- A tripled dose gave less LH; older men's testosterone did not rise; continuous exposure desensitised the pituitary within five days.
- The potent analogue TAK-448, held on, pushed testosterone to castration levels by day 8.
- Its trial in men with low testosterone was terminated for missing its primary endpoint.
- No human study has measured muscle, strength or body composition.
- Prohibited in sport at all times (S2.2.1); not approved; on FDA's compounding Category 2 list since 2023.
Limits of this page
The four trials are small and short, and hormone rises measured over hours or days say nothing about months. The PubMed and registry counts depend on the query wording and were taken on one date. TAK-448 is a more potent, longer-lived molecule than kisspeptin-10, so its castration effect is the clearest evidence of what sustained receptor stimulation does, not a measurement of kisspeptin-10 itself. The terminated trial's results are not posted to the registry, so the size of the miss is not known.
Sources and dates
- George JT, Veldhuis JD, Roseweir AK, et al. Kisspeptin-10 is a potent stimulator of LH and increases pulse frequency in men. J Clin Endocrinol Metab 2011;96:E1228–36 — PMID 21632807
- George JT, Veldhuis JD, Tena-Sempere M, et al. Kisspeptin-10 stimulates serum testosterone and LH secretion in men with type 2 diabetes and mild biochemical hypogonadism. Clin Endocrinol 2013;79:100–4 — PMID 23153270
- Ullah H, Nabi G, Zubair H, et al. Age-dependent changes in the reproductive axis responsiveness to kisspeptin-10 administration in healthy men. Andrologia 2019;51:e13219 — PMID 30590872
- Yeung AC, Phylactou M, Koysombat K, et al. Chronic subcutaneous kisspeptin-10 stimulates gonadotropin secretion for 12 days in healthy men. Eur J Endocrinol 2026;195:206–16 — PMID 42549827
- MacLean DB, Matsui H, Suri A, et al. Sustained exposure to the investigational kisspeptin analog, TAK-448, down-regulates testosterone into the castration range in healthy males and in patients with prostate cancer. J Clin Endocrinol Metab 2014;99:E1445–53 — PMID 24762108
- Matsui H, Masaki T, Akinaga Y, et al. Pharmacologic profiles of investigational kisspeptin/metastin analogues, TAK-448 and TAK-683, in adult male rats. Eur J Pharmacol 2014;735:77–85 — PMID 24747751
- ClinicalTrials.gov API v2, read 2026-09-24: NCT02381288 (Takeda, terminated, "did not meet the primary endpoint"), NCT02369796 (Takeda, terminated); intervention search
kisspeptin→ 36 records, none with a muscle or performance endpoint. - PubMed, searched 2026-09-24:
kisspeptin[tiab]→ 3,312; with trial publication types → 61; with muscle, lean mass or strength and humans[mh] → 11, all titles read. - World Anti-Doping Agency, 2026 Prohibited List, S2.2.1 — as mapped on this site's WADA status by compound.