Growth hormone secretagogue: how they work, what has been shown, and the IGF-1 ceiling

Before you read onResearch and educational information for adults, not medical advice. This entry explains one longevity term — what it means, why it matters and what the evidence says — and nothing here diagnoses, treats, cures or prevents any condition. Baseline labs come before anything, and your own physician has the final word. Longevity Bros offers coaching and written research protocols only — we do not sell, supply, source or ship any compound.

What it means

A growth hormone secretagogue (GHS) is any compound that stimulates the pituitary to release GH. Two classes: GHRH analogues (sermorelin, CJC-1295, tesamorelin) act on the GHRH receptor and amplify the natural pulse; ghrelin mimetics (GHRP-2, GHRP-6, ipamorelin, hexarelin, oral MK-677/ibutamoren) act on the ghrelin receptor and trigger a pulse. Combining one of each is additive, which is why CJC-1295 + ipamorelin is the common pairing.

Because the pituitary and the IGF-1 feedback loop stay in charge, the GH rise is physiological in shape — unlike injected GH, which bypasses both.

Why it matters for longevity

GH and IGF-1 fall by about 15% per decade after 30, and the decline tracks with sarcopenia, visceral fat and poorer sleep. Restoring the pulse is the idea. The counterweight is that lower IGF-1 is associated with longer life in several cohorts, so a secretagogue in a longevity plan is a trade-off to be made with eyes open and labs in hand.

What the evidence says

Tesamorelin is the licensed one: in two phase 3 trials (Falutz 2010, about 800 people with HIV lipodystrophy) it reduced visceral fat by about 15% over 26 weeks, with IGF-1 rising within range; fat returned after stopping. A 2024 trial reported reduced liver fat in non-HIV fatty liver.

MK-677 in older adults (Nass 2008, 65 people, one year) raised IGF-1 to young-adult levels and added about 1.6 kg of lean mass, with no gain in strength or function, plus raised fasting glucose and appetite. CJC-1295 and ipamorelin have human pharmacology studies showing sustained GH and IGF-1 rises, and no outcome trials. Sermorelin has small, older studies in GH-deficient children and adults.

How to measure or use it

IGF-1 is the marker: baseline, then at 6–8 weeks. Staying in the upper third of the age-adjusted range is the usual boundary; above range is the signal to stop.
Watch fasting glucose and HbA1c (GH is counter-insulin), water retention and carpal-tunnel symptoms.
The physiological secretagogues — deep sleep, fasting, hard training — raise GH pulses for free and are where any protocol starts.

CJC-1295 / ipamorelin (research page) — the pairing, what it is studied for, the labs
Tesamorelin (research page) — the licensed GHRH analogue
Hormones after 40 — the GH axis in context

Frequently asked questions

How is a secretagogue different from growth hormone?

It prompts your pituitary to release its own GH in pulses with feedback intact; injected GH bypasses both. The IGF-1 rise is usually smaller and self-limiting.

Which secretagogue has the best evidence?

Tesamorelin, by far: licensed on phase 3 trials for visceral fat in HIV lipodystrophy. The others have pharmacology studies, not outcome trials.

What is the risk of a high IGF-1?

Higher IGF-1 is associated with some cancers and with shorter life in several cohorts; it also raises glucose. That is why IGF-1 is checked and capped.

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