GHRP-6's most reproducible clinical effect is hunger — Wren 2001 established the parallel between ghrelin and GHRP-induced appetite, and subsequent work confirmed GHRP-6 as a robust orexigen via GHS-R1a in the hypothalamus.
2 human studies · 8 animal studies
Wren 2001: Ghrelin (and by parallel GHRP-6) increased free-choice buffet intake by 28% in healthy men.
Mechanism: GHS-R1a activation of NPY/AgRP neurons in the arcuate nucleus.
Effect attenuates with chronic dosing — short-acting orexigen.
Top citations
Wren 2001 — Ghrelin (parallel) appetite RCT
Bowers 1990 — Original GHRP/GHRH synergy
Our take
If your goal is to eat more, GHRP-6 works. For most users that's exactly the wrong direction. Older sibling to ipamorelin and largely outclassed.