Women and GH secretagogues: why men's data don't transfer

Women and men release growth hormone differently

Growth hormone is released in pulses, and the pattern differs by sex. A 1998 study comparing young men and women found that men had large nocturnal pulses and relatively small ones during the day, while women had more continuous secretion and more frequent pulses of more uniform size (human study) ¹. At rest, women in a 1999 study secreted 3.69 times more growth hormone per burst than men, with higher secretion between bursts and a larger total output (human study) ².

Age and body weight matter too. In 130 healthy adults spanning five decades, 24-hour pulsatile secretion fell with age and, even more strongly, with body mass index; the greater secretion in women was no longer detectable after age 50, and women over 50 had lower IGF-1 than men of similar age (human study) ³. A single fasting growth hormone test, the authors noted, says little about 24-hour secretion ³.

Estrogen changes growth hormone's effect

Estrogen does not just change how much growth hormone is released; it changes what growth hormone does. A 2004 review in Endocrine Reviews explains that oral, but not transdermal, estrogen impairs growth hormone's metabolic action in the liver, lowering IGF-1 production and fat burning, which can mean loss of lean tissue and gain of fat in postmenopausal women, and a weaker response to growth hormone treatment (review) ⁴. The route matters because estrogen swallowed as a pill passes through the liver first.

A randomised trial in 196 postmenopausal women confirmed it: oral estradiol lowered IGF-1 compared with placebo and with transdermal estradiol, while transdermal estradiol had no effect (randomised trial) ⁵. The pill makes a practical difference: in women with growth hormone deficiency, those on contraceptive pills containing ethinylestradiol needed significantly higher growth hormone doses and responded less than women on no estrogen or transdermal estrogen (clinical record review) ⁶.

Who the secretagogue studies actually included

Against that biology, look at who was studied. Ipamorelin's key human study of how the body handles it used eight healthy men at each dose level (human study) ⁷. The tesamorelin trials behind its approval were 86% men (drug label) ⁸. CJC-1295's 2006 study enrolled healthy adults aged 21 to 61, without separate results by sex in the abstract (human study) ⁹. An exception was a two-year trial of MK-677 (ibutamoren) in 65 adults aged 60 to 81, which included men, women taking hormone therapy and women not taking it (randomised trial) ¹⁰.

Much of ipamorelin's animal research, ironically, was in female rats ¹¹. But rat growth hormone patterns are themselves strongly sex-specific, and rodent results are not a substitute for human data. When a trial does include women, the useful question is whether it reports results for them separately; many do not, which leaves a pooled average dominated by whichever sex made up most of the participants, as with tesamorelin's mostly male trials ⁸.

Do women respond differently? A clue from growth hormone itself

The clearest evidence on sex differences in response comes from growth hormone itself rather than secretagogues. In a 26-week randomised trial in 57 women and 74 men aged 65 to 88, growth hormone raised lean body mass by 1.0 kg in women but 3.1 kg in men, and with added sex hormones by 2.1 kg against 4.3 kg; strength did not rise significantly in either sex except for a marginal gain in men given growth hormone with testosterone (randomised trial) ¹². Women responded, but less, and the strength gains people seek did not follow. Fat mass fell in women given growth hormone, with or without hormone therapy ¹², which is closer to what many women using these peptides say they want, but that was growth hormone itself, given by injection under medical supervision.

A related peptide shows how stark sex differences in hormone responses can be. Kisspeptin-10, which stimulates the reproductive axis, raised LH and FSH in men at low doses but did not change them in women in the first half of the menstrual cycle even at maximal doses (human study) ¹³. It is a reminder that a peptide's effect in men cannot simply be assumed in women.

Menopause, age and estrogen replacement

Part of the fall in growth hormone with age in women appears tied to menopause, but age itself matters too. A study compared eight women with premature menopause, aged 25 to 40, with eight postmenopausal women aged 51 to 70, before and after transdermal estradiol. Estradiol raised mean and basal growth hormone in both groups without changing pulse frequency, pulse size or IGF-1, and the younger women secreted significantly more growth hormone than the older women regardless of treatment (human study) ¹⁴. So a postmenopausal woman's growth hormone system differs from a premenopausal woman's, and both differ from a man's.

That has a practical consequence for anyone comparing their response to someone else's: whether a woman is pre- or postmenopausal, and whether she uses oral or transdermal estrogen, changes both her growth hormone output and how her liver responds to it ^{14 5}.

Blood sugar effects by sex

Raising growth hormone tends to worsen insulin sensitivity, and the details differ by sex. In older adults given growth hormone, women showed higher insulin levels after a glucose drink without higher glucose, while men showed higher glucose and insulin; insulin sensitivity fell in both (randomised trial) ¹⁵. In the two-year MK-677 trial, which included women, fasting glucose rose by about 0.3 mmol/L and insulin sensitivity fell, effects our blood sugar guide covers in detail ¹⁰.

What women using these peptides report

A study of 23 discussion threads on nine bodybuilding forums found women using CJC-1295 for weight loss, muscle, skin, sleep and injury healing, usually alongside other performance and image drugs, and worrying about how sex differences in growth hormone pulses affect dosing and about long-term consequences (qualitative study) ¹⁶. Those worries are well founded: the dosing schedules circulating online were built on men's physiology and studies of men.

What this means in practice

Several practical points follow from the evidence. First, a woman's growth hormone pattern and IGF-1 depend on age, weight and whether she takes oral estrogen ^{3 5}. Second, IGF-1, often used online to judge a secretagogue's effect, is itself lowered by oral estrogen, so it is a poor guide for women on the pill or oral hormone therapy ^{5 6}. Third, growth-hormone-raising compounds affect blood sugar; our blood sugar guide covers MK-677's effects. Fourth, none of these research secretagogues is approved, so no dose has been established for anyone, women included ¹¹.

What a doctor would want to check

For the one approved growth hormone releasing peptide in this group, the label spells out monitoring that is a sensible guide for related compounds. The EGRIFTA WR label warns that glucose intolerance or diabetes may develop with tesamorelin and advises evaluating glucose status before and during treatment, and it contraindicates use in pregnancy ⁸. A doctor assessing a woman considering any growth-hormone-raising compound would also want to know her menopausal status and any estrogen she takes, since both change growth hormone and IGF-1 ^{14 5}, and would interpret an IGF-1 result with those in mind rather than against men's ranges ³. Our guide to talking to your doctor about peptides includes a script.

Pregnancy and fertility

The EGRIFTA WR label contraindicates tesamorelin in pregnancy, because reducing visceral fat offers no benefit in pregnancy and could harm the fetus (drug label) ⁸. The research secretagogues have no pregnancy safety data at all ¹¹. Anyone who is pregnant, trying to conceive or breastfeeding should not use them.

Sport

Growth hormone secretagogues and releasing peptides, including ipamorelin, CJC-1295 and MK-677, are named on the WADA Prohibited List under S2.2.4, for women and men alike ¹¹. Our WADA hub lists them.

Questions to ask before using a GH peptide

• Was the evidence for this peptide gathered in women at all?
• Am I taking oral estrogen or a combined pill, which changes growth hormone's effect and IGF-1?
• Am I pregnant, planning pregnancy or breastfeeding?
• Do I have blood sugar problems?
• Am I subject to anti-doping rules?

The bottom line

Women's growth hormone system works differently from men's: steadier, more frequent pulses, a sex difference that fades after 50, and a strong interaction with oral estrogen that lowers IGF-1 and blunts growth hormone's action. The human studies behind popular secretagogues were largely in men, and in older adults growth hormone itself built less lean mass in women than men. Doses and promises borrowed from men's data do not transfer.

Frequently asked questions

Do women release growth hormone differently from men?

Yes. Women have more frequent, more uniform growth hormone pulses, while men's release is dominated by large pulses at night. The difference fades after about age 50.

Does the birth control pill affect growth hormone?

Pills containing ethinylestradiol, and oral estrogen generally, blunt growth hormone's effect on the liver and lower IGF-1. Women with GH deficiency on such pills needed higher GH doses.

Is ipamorelin studied in women?

Its key human pharmacokinetic study used only men. Much of its animal work was in female rats, which does not substitute for human data.

Do women respond to growth hormone like men?

In a trial in older adults, growth hormone raised lean mass by 1.0 kg in women against 3.1 kg in men, and strength did not improve significantly in women.

Are GH peptides safe in pregnancy?

No. Tesamorelin's label contraindicates it in pregnancy, and research secretagogues have no pregnancy safety data.

Related on Grey Peptides

• Ipamorelin
• Ibutamoren (MK-677)
• Peptides and blood sugar

Sources

1. Jaffe, C. A., et al. (1998). Regulatory mechanisms of growth hormone secretion are sexually dimorphic. J Clin Invest, 102(1), 153-64. PMID: 9649569
2. Wideman, L., et al. (1999). Effects of gender on exercise-induced growth hormone release. J Appl Physiol (1985), 87(3), 1154-62. PMID: 10484590
3. Roelfsema, F., et al. (2016). Growth Hormone Dynamics in Healthy Adults Are Related to Age and Sex and Strongly Dependent on Body Mass Index. Neuroendocrinology, 103(3-4), 335-44. PMID: 26228064
4. Leung, K. C., et al. (2004). Estrogen regulation of growth hormone action. Endocr Rev, 25(5), 693-721. PMID: 15466938
5. Sonnet, E., et al. (2007). Effects of the route of oestrogen administration on IGF-1 and IGFBP-3 in healthy postmenopausal women: results from a randomized placebo-controlled study. Clin Endocrinol (Oxf), 66(5), 626-31. PMID: 17492948
6. Phelan, N., et al. (2012). Quantification of the adverse effect of ethinylestradiol containing oral contraceptive pills when used in conjunction with growth hormone replacement in routine practice. Clin Endocrinol (Oxf), 76(5), 729-33. PMID: 22098528
7. Gobburu, J. V., et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res, 16(9), 1412-6. PMID: 10496658
8. Theratechnologies. EGRIFTA WR (tesamorelin) US prescribing information, sections 4, 8.1 and 14 (trial population 86% male). DailyMed version 2; read October 3, 2026.
9. Teichman, S. L., et al. (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab, 91(3), 799-805. PMID: 16352683
10. Nass, R., et al. (2008). Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med, 149(9), 601-11. PMID: 18981485
11. Grey Peptides encyclopedia entries for ipamorelin (animal studies in female rats), MK-677 (ibutamoren), tesamorelin and CJC-1295 (statuses; WADA S2.2.4). Read October 3, 2026.
12. Blackman, M. R., et al. (2002). Growth hormone and sex steroid administration in healthy aged women and men: a randomized controlled trial. JAMA, 288(18), 2282-92. PMID: 12425705
13. Jayasena, C. N., et al. (2011). The effects of kisspeptin-10 on reproductive hormone release show sexual dimorphism in humans. J Clin Endocrinol Metab, 96(12), E1963-72. PMID: 21976724
14. Lieman, H. J., et al. (2001). Effects of aging and estradiol supplementation on GH axis dynamics in women. J Clin Endocrinol Metab, 86(8), 3918-23. PMID: 11502833
15. Münzer, T., et al. (2009). Growth hormone and sex steroid effects on serum glucose, insulin, and lipid concentrations in healthy older women and men. J Clin Endocrinol Metab, 94(10), 3833-41. PMID: 19602554
16. Van Hout, M. C., et al. (2016). Netnography of Female Use of the Synthetic Growth Hormone CJC-1295: Pulses and Potions. Subst Use Misuse, 51(1), 73-84. PMID: 26771670

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.