Ghrelin, the Hunger Hormone: What It Does and What Changes It
Also known as:
often mentioned with:
community guides:
Appetite hormones and related pages:
Anonymous user report. Not medical advice. Peptides discussed are not FDA-approved for the uses described. Editorial process →
What is ghrelin?
Ghrelin is a 28-amino-acid hormone made mainly in the stomach. It was identified in 1999 as the body's own key for the growth hormone secretagogue receptor (GHS-R1a), and it only works once a fatty-acid group is attached to its third amino acid (Kojima 1999). The name comes from "ghre", an old root for "grow", because it releases growth hormone.
It is best known as the hunger hormone. In people eating on a fixed schedule, blood ghrelin roughly doubled just before each meal and fell to its low point within an hour of eating (Cummings 2001). When healthy volunteers were given a ghrelin infusion, every one of them ate more at a buffet, on average 28% more (Wren 2001). It works roughly in the opposite direction to GLP-1, which signals fullness.
Ghrelin vs leptin
Ghrelin and leptin are often called the hunger and fullness hormones, but they work on different time scales. Ghrelin is a short-term, meal-to-meal signal from the stomach. Leptin is a long-term signal from fat cells about how much energy is stored. Last reviewed October 18, 2026.
| Feature | Ghrelin | Leptin |
|---|---|---|
| Made in | Stomach | Fat cells |
| Main message | Time to eat | Energy stores are full |
| Time scale | Rises before meals, falls after | Tracks body fat over weeks and months |
| After short sleep | Higher | Lower |
| After diet weight loss | Higher, still raised a year later | Lower, still reduced a year later |
| Approved drugs | Anamorelin, a receptor activator (Japan only) | Metreleptin (lipodystrophy only) |
What raises and lowers ghrelin in studies
People search "how to reduce ghrelin" a lot. The research below describes what moved ghrelin in study groups; most studies were small, and a lower ghrelin level is not a proven weight-loss method on its own. It is a summary of findings, not advice.
| Factor | What happened to ghrelin | Study |
|---|---|---|
| Eating a meal | Fell to its low point within about an hour | Cummings 2001 (10 adults) |
| Protein, carbs or fat | All suppressed it; protein the most overall, fat the least. After a carb drink it rebounded above the starting level 3 to 6 hours later | Foster-Schubert 2008 (16 adults) |
| Two nights of short sleep | Up 28%, with hunger up 24%, vs two nights of longer sleep | Spiegel 2004 (12 young men) |
| Habitual short sleep | About 15% higher at 5 hours of sleep vs 8 hours | Taheri 2004 (1,024 adults) |
| Diet-induced weight loss | Up 24% across the day after losing 17% of body weight | Cummings 2002 |
| One year after a diet | Still above the pre-diet level, along with hunger | Sumithran 2011 (50 adults) |
| Gastric bypass | 77% lower than in normal-weight controls, with the meal-time rhythm gone | Cummings 2002 (5 patients) |
| Sleeve gastrectomy | Fasting ghrelin fell markedly; in the same trial it did not fall significantly after gastric bypass | Karamanakos 2008 (32 patients) |
Ghrelin, dieting and GLP-1 medicines
The dieting results explain why ghrelin matters in weight-loss discussions: when people lose weight by eating less, ghrelin rises and hunger tends to rise with it, which pushes toward regain. GLP-1 medicines such as semaglutide and tirzepatide act on GLP-1 (and, for tirzepatide, GIP) receptors, not on the ghrelin receptor; they add a fullness signal rather than switching hunger hormones off. The constant food thoughts users describe before these drugs are covered on food noise. There is no approved drug that blocks ghrelin.
Ghrelin and growth-hormone peptides
GH secretagogues such as GHRP-6, GHRP-2, ipamorelin and the oral compound MK-677 act on the same receptor as ghrelin, which is why hunger is one of their most reported effects. They mimic ghrelin at the receptor rather than raising ghrelin itself. GHRH-type peptides such as sermorelin and tesamorelin use a different receptor. The only approved ghrelin-receptor drug is anamorelin (Adlumiz), approved in Japan in January 2021 for cancer cachexia; it is not approved in the US. Ipamorelin, GHRP-2 and GHRP-6 remain in FDA compounding Category 2, and the WADA Prohibited List names ghrelin (lenomorelin) and these receptor mimetics as banned at all times for tested athletes. Last reviewed: October 2026.
Anonymous reports mentioning ghrelin
No reports found.
If a ghrelin-receptor compound changed your appetite, submit the account.
Submit yoursCommunity Q&A
- What is ghrelin?
- A 28-amino-acid hormone made mainly in the stomach. It signals hunger before meals and also triggers growth hormone release through the GHS-R1a receptor.
- What is the difference between ghrelin and leptin?
- Ghrelin is a short-term hunger signal from the stomach that rises before meals. Leptin is a long-term signal from fat cells about stored energy. Short sleep and diet weight loss push ghrelin up and leptin down.
- How do you reduce ghrelin?
- In studies, ghrelin fell after meals (most after protein), and it was higher after short sleep and after diet-induced weight loss. Sleeve gastrectomy lowered it markedly. No supplement has been shown to lower ghrelin, and none of this is personal advice.
- Does sleep affect ghrelin?
- Yes, in studies. Two nights of restricted sleep raised ghrelin 28% in young men, and adults who habitually slept 5 hours had about 15% higher ghrelin than those sleeping 8.
- Why do GHRP-6 and MK-677 make you hungry?
- They activate the ghrelin receptor (GHS-R1a), mimicking the hunger hormone.
- Is there an approved ghrelin drug?
- Anamorelin, a ghrelin-receptor agonist, is approved in Japan for cancer cachexia. None is FDA approved, and no ghrelin blocker is approved.
Sources
Anonymous first-hand reports plus sourced context — educational only, not medical advice. Editorial policy & corrections.