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The Hunger Hormone – Ghrelin

Often referred to as the “hunger hormone,” ghrelin performs numerous functions beyond signaling hunger to the brain.

Ghrelin is a hormone produced by the stomach. Small amounts are also released by other parts of the body, such as the brain, small intestine, and pancreas.

  • Increases food intake and assists in fat storage.
  • Triggers the pituitary gland to release growth hormones.
  • Plays a role in regulating sugars and the release of insulin, the hormone responsible for processing sugar.
  • Contributes to muscle protection and bone formation and metabolism.

Ghrelin and leptin

Ghrelin and leptin are among the many hormones that regulate appetite and fullness, participating in the extensive network of pathways that control body weight. While ghrelin increases appetite, leptin decreases it.

  • Ghrelin, produced in the stomach, signals the brain when hunger is present.
  • Leptin is produced by fat cells and informs the brain when sufficient energy has been stored and a feeling of fullness is achieved.

Ghrelin is involved in the short-term control of appetite, whereas leptin is responsible for long-term weight regulation.

Ghrelin Function

  • Signals the hypothalamus to increase appetite.
  • Promotes fat storage.
  • Stimulates the pituitary gland to release growth hormones.
  • Stimulates the digestive system to move food from the stomach through the small and large intestines.
  • Contributes to controlling insulin release.
  • Plays a role in protecting cardiovascular health.

Ghrelin is released by the stomach when it is empty or mostly empty. Levels of ghrelin are typically highest right before mealtimes.

Ghrelin Disorders

Ghrelin levels increase when the stomach is empty, signaling the brain that it’s time to eat. After eating, ghrelin levels decrease.

Certain conditions can lead to chronically low or high ghrelin levels:

Low ghrelin

Ghrelin levels are usually lower in individuals with obesity. Some researchers suggest that this connection may indicate a higher sensitivity to ghrelin, causing greater feelings of hunger even with lower levels of the hormone.

Low ghrelin is also associated with certain gastrointestinal diseases, including:

  • Chronic gastritis
  • Functional dyspepsia
  • H. Pylori infection
  • Irritable bowel syndrome (IBS)

High ghrelin

Increases in ghrelin levels may occur with restricted caloric intake, such as during a restrictive diet. High ghrelin may also be linked to biological and genetic conditions such as:

  • Anorexia nervosa
  • Cachexia, a condition that causes muscle wasting
  • Celiac disease
  • Inflammatory bowel disease (IBD)
  • Prader-Willi syndrome

Gastric Bypass Surgery & Ghrelin

Gastric bypass surgery and sleeve gastrectomy, both surgical treatments for severe obesity, result in sustained lower levels of ghrelin. This reduction is believed to contribute to long-term weight control. A smaller stomach size post-surgery is thought to be one of the factors responsible for lower ghrelin levels and subsequent weight loss.

Ghrelin Maintenance

  • Avoiding fad or yo-yo dieting, which involves frequent weight gain and loss.
  • Consuming a diet rich in healthy carbohydrates, such as whole grains, and lean proteins like chicken or fish.
  • Limiting processed foods, especially those high in sugar, high-fructose corn syrup, and salt.
  • Sleeping at least seven to eight hours nightly.
  • Staying hydrated by drinking plenty of water and eating water-rich foods such as fruits and vegetables.
  • Managing stress, as stress may increase ghrelin.

Influencing Ghrelin Level

Ghrelin levels tend to fluctuate with food intake. Hydration can decrease ghrelin, while dehydration may increase it.

The types of foods consumed affect ghrelin. For instance, foods high in protein or healthy carbohydrates lower ghrelin levels more effectively than foods high in fat.


  • Ghrelin is a hormone produced in the stomach,
  • Ghrelin is released when the stomach is empty to signal the brain that it is time to eat.
  • It also signals the pituitary gland to release growth hormones,
  • plays a role in insulin release, and protects cardiovascular health.