Ghrelin: the basics
What is it?
A hormone made mainly in the stomach that signals hunger and can stimulate growth-hormone release.
Research paper 1 ↗Research paper 2 ↗What do people claim it helps with?
Improved appetite, weight gain during illness and sometimes recovery or anti-aging. These proposed treatment goals need separate evidence.
What has research actually shown?
Small controlled human infusion studies found increased hunger and food intake. This does not establish lasting recovery from illness-related weight loss or an anti-aging benefit.
Research paper 1 ↗Research paper 2 ↗Has this been demonstrated in people?
Human physiology and small human administration studies, alongside laboratory and animal research. These studies do not establish a routine treatment for the claims listed here.
Research paper 1 ↗Research paper 2 ↗What side effects, risks and unknowns should I understand?
It can affect appetite, growth hormone and glucose regulation. Long-term treatment safety and interactions remain uncertain.
Research paper 1 ↗Research paper 2 ↗Is it an approved medicine?
The native hormone described here is not an FDA-approved standalone medicine. Medicines that act on similar pathways are different products with their own approvals.
Research paper 1 ↗Research paper 2 ↗Approval here means U.S. FDA approval and applies to a particular product, formulation and use. This is a starting overview, not a complete side-effect list. Sources checked 10 October 2026; independent scientific review pending.
How is it used or studied?
Primarily a research hormone, including experimental administration in appetite studies.
Different routes and formulations can have different effects. A study of one product does not validate every product with the same peptide name.
A common misunderstanding
A ghrelin-receptor drug is a different substance from native ghrelin.
What should I ask a clinician?
- What diagnosis or goal are we trying to address, and what established options are available?
- Was the expected benefit shown in people like me, using this exact product?
- How could my medicines, health conditions or pregnancy plans affect the risks?
- What monitoring is needed, and what would tell us the treatment is helping or should be stopped?
What do the research words mean?
- Peptide
- A short chain of amino acids, the building blocks of proteins.
- Preclinical
- Research in cells, tissues or animals before dependable treatment evidence in people.
- Controlled trial
- A study comparing a treatment with another treatment or a placebo to help separate its effects from other explanations.
- Biomarker
- A measurement, such as a hormone level. A change does not necessarily mean someone feels better or lives longer.
Ghrelin Evidence & Clinical Profile
Human Study Limits
Ghrelin has been investigated in clinical contexts. Patient outcomes must be evaluated against study size, design, and control cohorts.
Laboratory & In Vivo Assays
Cellular and animal disease models examine receptor binding affinities and signaling cascades, which require human confirmation.
What is Ghrelin?
Acylated Ghrelin (Hunger Hormone) is An endogenous 28-amino-acid peptide hormone produced predominantly in the stomach. The first circulating hormone shown to stimulate food intake in humans, it requires serine-3 octanoylation to activate the growth hormone secretagogue receptor (GHS-R). Aliases include: Acylated ghrelin, Motilin-related peptide, Growth hormone secretagogue hormone.
- Sequence (one-letter)
- GSS(octanoyl)FLSPEHQRVQQRKESKKPPAKLQPR
- Molecular formula
- C149H249N47O42
- Molecular weight
- 3370.9 g/mol
- CAS Number
- 258279-04-8
- UNII Code
- UXG268Q86R
- PubChem CID
- 16133832
Identifiers checked against PubChem and FDA's Global Substance Registration System on 13 October 2026. FDA substance record ↗ · PubChem record ↗ See all names and codes in the peptide name index.
Clinical Trials & Human Cohorts
Human research can examine tolerability, symptoms or patient outcomes. The design and comparator determine what each result can establish.
Ghrelin enhances appetite and increases food intake in humans [1]
What was reported
Intravenous ghrelin increased energy consumed from a free-choice buffet by a mean 28% versus saline, with higher appetite scores and no change in gastric emptying.
What limits the conclusion
Small exploratory physiology cohort; acute single-meal evaluation.
Ghrelin increases energy intake in cancer patients with impaired appetite: acute, randomized, placebo-controlled trial [2]
What was reported
Ghrelin infusion increased buffet energy intake by 31% versus saline, every patient ate more, and meal appreciation scores rose by 28%; no side effects were observed.
What limits the conclusion
Very small preliminary study with a single acute infusion; no weight, lean mass or survival endpoints.
How the compound may work
Mechanisms describe how Ghrelin may affect biological processes. Laboratory findings and patient outcomes answer different questions.
GHS-R Ligand & Pituitary GH Release
Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor; the acylated peptide specifically releases GH, and O-n-octanoylation at serine 3 is essential for activity. [3]
Ghrelin O-Acyltransferase (GOAT)
The acyltransferase GOAT octanoylates ghrelin, producing the active acylated form. [4]
Areas Being Studied
These research topics reflect active areas of scientific exploration, distinct from unverified commercial marketing claims.
Compare the study designs.
| Study | Design / sample | Outcome type | Key limitation |
|---|---|---|---|
| Landmark Wren Infusion · 2001 [1] | Randomized double-blind crossover study n = 9 |
Clinical endpoint evaluation | Small exploratory physiology cohort; acute single-meal evaluation. |
| Cancer Anorexia Trial · 2004 [2] | Acute randomized placebo-controlled crossover trial n = 7 |
Clinical endpoint evaluation | Very small preliminary study with a single acute infusion; no weight, lean mass or survival endpoints. |
Regulatory Status & Clinical Safety
Regulatory Classification
Endogenous hormone. Synthetic ghrelin mimetics and antagonists are under investigational development.
Safety Realities & Impurities
Safety depends on the molecule, formulation, route and evidence. A laboratory purity measurement alone cannot establish safety for human use.
Clinical Trials Registry Records
Official registry records from ClinicalTrials.gov. Study registration does not imply government endorsement or guaranteed efficacy.
WADA & Anti-Doping Regulations
WADA Anti-Doping Status
Ghrelin is not prohibited under current World Anti-Doping Agency (WADA) regulations. However, athletes must ensure unregulated preparations or unverified vendor products do not violate Section S0 (Non-approved substances). Last verified: October 2026.
Research Timeline
-
1999
Discovery
Kojima and colleagues purify ghrelin from rat stomach and identify human ghrelin. [3]
-
2001
Human Food Intake Study
Wren et al. report that ghrelin infusion increases food intake in healthy volunteers (JCEM). [1]
-
2008
GOAT Identified
Yang and colleagues discover ghrelin O-acyltransferase (GOAT) enzyme responsible for octanoylation. [4]
What Researchers Still Don't Know
Long-term safety profiles
Multi-year observational data in broader heterogeneous cohorts remains uncharacterized.
Optimal dose-response thresholds
Comparative trials optimizing minimal effective exposure versus adverse event rates.
Formulation bioavailability
Differences between oral, subcutaneous, and modified peptide delivery vehicles.
References
Primary sources verified against PubMed / NLM and regulatory databases.
-
Landmark Clinical RCT
Ghrelin enhances appetite and increases food intake in humans ↗ (external website)
- Clinical Trial
-
Discovery Paper
Ghrelin is a growth-hormone-releasing acylated peptide from stomach ↗ (external website)
- Enzymology Paper