Ghrelin is a hormone that is produced and released in the stomach. People often refer to it as the “hunger hormone” because it increases appetite. It also promotes blood sugar regulation, prevents muscle breakdown, and protects the heart. In this Honest Nutrition feature, we explore what ghrelin is, its functions, and how a person can manage levels in their body.
Written by Lindsey DeSoto, RDN, LD on March 3, 2022 — Fact checked by Rita Ponce, Ph.D.
This series of Special Features takes an in-depth look at the science behind some of the most debated nutrition-related topics, weighing in on the facts and debunking the myths.
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Ghrelin is a hormone mainly produced in the stomach when it is empty. It is also produced in the small intestine, brain, and pancreas.
Ghrelin travels through the bloodstream to the brain, where it acts on the hypothalamus. The hypothalamus is a part of the brain, which produces hormones that regulate hunger, mood, thirst, and many other important functions within the body.
Ghrelin is often referred to as the hunger hormone because its primary role is to regulate appetite. When ghrelin activates its receptor — growth hormone secretagogue receptor — it causesTrusted Source a person to eat more food and store extra fat.
In people who are trying to lose weight or who have recently lost weight, ghrelin levels are often higher, making it challenging to maintain weight loss.
For example, one studyTrusted Source from 2020 looked at people with diabetes who participated in a 2-year weight management program. Participants who initially lost weight slowly regained it over the study duration. Researchers found that weight loss was associated with increased ghrelin levels and increased hunger, which might make it difficult to keep weight off.
Ghrelin can also signal the body to decrease brown fat thermogenesis. When this happens, the body burns less fat at rest. Brown fat is known for its thermogenic propertiesTrusted Source and ability to increase overall calories burned.
Studies show that ghrelin also affects a person’s sleep/wake cycle, taste sensation, and reward-seeking behavior.
