Research brief · 2026-09-09
What Do Growth Hormone Secretagogues Actually Do?
Growth hormone secretagogues are compounds that prompt the pituitary gland to release more of the body's own growth hormone. Names that circulate include ipamorelin, CJC-1295, sermorelin and MK-677. None of those is approved for human use. Tesamorelin, a related compound, is a prescription medication approved for fat build-up associated with HIV.
Start with what has never been tested. Ipamorelin and CJC-1295 have both been through registered human trials, but the indications were gut recovery after bowel surgery and, for CJC-1295, HIV-associated visceral fat. None measured muscle mass, strength or a body-composition outcome relevant to ageing. A 2026 review in The American Journal of Sports Medicine by Mayfield and colleagues found the combination improved muscle contractile force in mice with steroid-induced muscle loss, and noted the findings were limited to animal studies.
MK-677 has the most human data, and it is the clearest illustration of the gap between a biomarker and an outcome. Sevigny and colleagues in Neurology in 2008 ran a twelve-month randomised trial in 563 patients with Alzheimer's disease. IGF-1 rose by about sixty percent at six weeks and seventy-three percent at one year. On every clinical measure, cognition, daily function, and global impression, there was no difference from placebo.
The one ageing-focused trial of a GHRH analogue, by Khorram and colleagues in the Journal of Clinical Endocrinology and Metabolism in 1997, followed nineteen adults aged 55 to 71 for five months. Growth hormone and IGF-1 rose within two weeks. Lean mass, insulin sensitivity and wellbeing improved in the men but not the women, and the authors could not explain why.
The pattern across the class is consistent: these compounds reliably move growth hormone and IGF-1 in the blood. Whether that translates into anything for muscle in ageing adults is mostly untested, the trials were short, in clinical populations, and silent on long-term safety. Questions about any of these belong with a physician.
Sources
- Sevigny JJ, Ryan JM, van Dyck CH, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial
- Neurology 2008
- Khorram O, Laughlin GA, Yen SS. Endocrine and metabolic effects of long-term administration of [Nle27]growth hormone-releasing hormone-(1-29)-NH2 in age-advanced men and women
- The Journal of Clinical Endocrinology and Metabolism 1997
- Mayfield CK, Bolia IK, Feingold CL, et al. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians
- The American Journal of Sports Medicine 2026
Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.