Ghrelin is a hormone that was believed to accumulate during periods of fasting and is found in the body in high concentrations just before meals. It is dubbed the "hunger hormone" because it has been shown that administration of pharmacological doses acts in the brain to stimulate hunger and increase food intake in animal models and humans.
The ghrelin hormone is unique in that it requires acylation (the addition of a fatty acid) by a specific enzyme (ghrelin O-acyl transferase, or GOAT) for activation. Originally it was assumed that the fatty acids attached to ghrelin by GOAT were produced by the body during fasting.
Instead, ghrelin is actually activated by ingested dietary fats, and behaves more like a fat sensor in the stomach that tells the brain when calories are available for calorie-burning activities.
In the study, lab mice without the GOAT enzyme were observed to acculumate less fat, while those with over-expressed GOAT accumulated more fat.
Although the study can't completely be applied to humans, researchers think it will be an important idea to consider in how ghrelin can aid the results of gastric bypass surgery. —ScienceDaily