Ghrelin is essentially your body's hunger alarm clock. Made primarily in your stomach, this little protein messenger is what makes you feel hungry before meals and helps drive your appetite. Think of it as your internal dinner bell – when your stomach is empty, ghrelin levels rise and start sending "time to eat" signals to your brain. After you eat, those levels drop off, which is why you feel satisfied.
Here's how it actually works in your body: ghrelin travels through your bloodstream and docks onto special receivers in your brain, particularly in areas that control hunger and hormone production. When it connects with these brain receptors, it's like flipping switches that make you want food while also telling your pituitary gland to release growth hormone. Your brain essentially gets two messages at once – "find food" and "release helpful hormones."
What's fascinating is that ghrelin comes in two versions. The active form crosses into your brain to create that hungry feeling and trigger growth hormone release, while the inactive form seems to have completely different jobs, like protecting your heart and reducing inflammation. Your ghrelin naturally peaks when you're fasting and crashes after eating, creating this elegant cycle that keeps your energy balance in check while also influencing your sleep and growth processes.
Dosage Information
Typical Dose
N/A — reference compound. See MK-677 or Hexarelin for ghrelin receptor agonists
Frequency
N/A
Administration
Reference compound
Half-Life
10–30 minutes
Notes
Native ghrelin is not used therapeutically due to short half-life and complex acylation requirements. This entry provides mechanistic context for the ghrelin receptor agonist class including MK-677 and all GHRPs.
Why this matters
Rapidly degraded; MK-677 and other mimetics provide sustained ghrelin receptor activation.
Where does Ghrelin sit?
See how this peptide compares across all 150 peptides in our database.
Evidence Score
0.73
Compound Data
Molecular Formula
C149H249N47O42
Molecular Weight
3370.90 g/mol
IUPAC Name
(4S)-4-[[(2S)-1-[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[(2-aminoacetyl)amino]-3-hydroxypropanoyl]amino]-3-octanoyloxypropanoyl]amino]-3-phenylpropanoyl]amino]-4-methylpentanoyl]amino]-3-hydroxypropanoyl]pyrrolidine-2-carbonyl]amino]-5-[[(2S)-1-[[(2S)-5-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-5-amino-1-[[(2S)-5-amino-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-6-amino-1-[(2S)-2-[(2S)-2-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-5-amino-1-[(2S)-2-[[(1S)-4-carbamimidamido-1-carboxybutyl]carbamoyl]pyrrolidin-1-yl]-1,5-dioxopentan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxopropan-2-yl]carbamoyl]pyrrolidine-1-carbonyl]pyrrolidin-1-yl]-1-oxohexan-2-yl]amino]-1-oxohexan-2-yl]amino]-3-hydroxy-1-oxopropan-2-yl]amino]-4-carboxy-1-oxobutan-2-yl]amino]-1-oxohexan-2-yl]amino]-5-carbamimidamido-1-oxopentan-2-yl]amino]-1,5-dioxopentan-2-yl]amino]-1,5-dioxopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]amino]-5-carbamimidamido-1-oxopentan-2-yl]amino]-1,5-dioxopentan-2-yl]amino]-3-(1H-imidazol-4-yl)-1-oxopropan-2-yl]amino]-5-oxopentanoic acid
PubChem CID
16133832Potential Side Effects
Ghrelin discussions
Quick Facts
- Administration
- Reference compound
- Typical Dose
- N/A — reference compound. See MK-677 or Hexarelin for ghrelin receptor agonists
- Frequency
- N/A
- References
- 0 curated + 47 from PubMed
- Clinical Trials
- 48 registered
- Evidence Score
- 0.7 / 100
Frequently Asked Questions about Ghrelin
What is Ghrelin?
Ghrelin is a 28-amino-acid peptide hormone produced primarily in the stomach that functions as the body's primary hunger signal and a potent GH secretagogue. It is often called the hunger hormone and plays central roles in energy homeostasis appetite regulation GH secretion and metabolic function. Ghrelin declines after meals and rises before them creating the hunger drive. Beyond appetite ghrelin has important effects on sleep cardiovascular function immune modulation and stress response. It is the endogenous ligand for the ghrelin receptor that synthetic compounds like MK-677 and Hexarelin target.
How does Ghrelin work?
Ghrelin acts through the growth hormone secretagogue receptor (GHSR-1a) expressed in the hypothalamus pituitary stomach and other tissues. In the hypothalamus it activates neuropeptide Y and AgRP neurons in the arcuate nucleus stimulating appetite and reducing energy expenditure. In the pituitary it synergizes with GHRH to produce robust GH pulses. Ghrelin exists in two forms: acylated ghrelin (AG) which is the active form that crosses the blood-brain barrier and activates GHSR-1a and desacyl ghrelin (DAG) which has distinct effects including anti-inflammatory and cardioprotective actions through different receptors. Circulating ghrelin levels are highest during fasting and lowest after eating. In sleep ghrelin promotes slow-wave sleep and is thought to mediate some of the GH release that occurs during deep sleep stages.
What is the recommended dosage for Ghrelin?
The typical dose is N/A — reference compound. See MK-677 or Hexarelin for ghrelin receptor agonists. N/A. Administration: Reference compound. Native ghrelin is not used therapeutically due to short half-life and complex acylation requirements. This entry provides mechanistic context for the ghrelin receptor agonist class including MK-677 and all GHRPs.
What are the side effects of Ghrelin?
N/A for native ghrelin — see ghrelin receptor agonist entries
Questions reflect common community inquiries. This is not medical advice.