Hunger hormone
The Direction Matters and it is the Opposite of most Hormone Nodes: you want this restrained, not raised. Ghrelin is the only circulating signal known to initiate a meal — it climbs through the hours before you eat and falls once you have. It is leptin’s counterpart, and where leptin says how much fat you carry, ghrelin says how long it has been. And it is why weight regained is not a failure of will: after weight loss ghrelin rises and stays risen, so the same person is asked to eat less while being told to eat more, by their own bloodstream.
In depth
The hunger signal from an empty stomach — the only circulating hormone known to increase appetite. It rises before meals you expect, which makes it as much a learned rhythm as a metabolic one.
What drives it
Restores fullness signal reduces it.
Leptin and ghrelin are opposing arms of appetite regulation.
What it drives
It reduces Curbs appetite.
10.3389/fnins.2012.00024 — Ghrelin is the orexigenic signal, rising before meals. doi 10.3389/fnins.2012.00024
It increases Growth hormone.
10.3389/fendo.2021.636403 — Ghrelin is a growth hormone secretagogue - the receptor is named GHS-R for that reason. doi 10.3389/fendo.2021.636403
It reduces Stomach contents rising.
10.1007/s12664-011-0124-6 — Drawn from reviews of neighboring outcomes rather than from studies of this outcome itself, which is weaker evidence, and the map marks it so. doi 10.1007/s12664-011-0124-6
It reduces Releases stored fat.
10.1080/21623945.2021.1945787 — the full STIMULATOR list, named together in the arabic reference and nowhere else in this evidence set: 'هناك مجموعة من الهرمونات داخل جسم الإنسان التي تقوم بتحفيز تحلل الدهن مثل أدرينالين ونورإبينفرين وغريلين وتستوستيرون وكورتيزول بالإضافة إلى هرمون النمو. تعمل هذه الهرمونات على إطلاق المستقبلات المقترنة بالبروتين ج، والتي بدورها تفعّل محلقة الأدينيليل' = epinephrine, norepinephrine, ghrelin, testosterone, cortisol and growth hormone all stimulate fat release, acting through G-protein-coupled receptors that activate adenylate cyclase (ar.wikipedia.org — تحلل الدهن (arabic)). Three of those six had NO connection drawn to fat release at all before this. The practical point: the body has six ways to open this door, and several of them ARE things a person controls — sleep, training and fasting raise growth hormone; an empty stomach raises ghrelin. And one of the six is cortisol, which is also a stress hormone: the same signal that opens this door carries costs elsewhere. doi 10.1080/21623945.2021.1945787
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.