Ghrelin – The Hunger Hormone
Ghrelin, the hunger hormone, acts with leptin to affect our appetite and maintain the body’s set-point. It is a peptide produced in the stomach. It may also be produced in the hypothalamus of the brain.
Ghrelin levels rise just before mealtime, and then decline when we eat. It seems that just thinking about food also causes a rise in ghrelin. (Think of ghrelin as triggering stomach growling.)
Looking at or smelling food often stimulates hunger, and may trigger our appetites even before our usual mealtime. Ghrelin may also be the mediator of this behavior. Rats who were able to look at food but were not allowed to eat produced a rise in ghrelin secretion.
Ghrelin also increases with sleep deprivation. Leptin, a hormone that signals satiety, goes down at the same time as ghrelin goes up. An increased ratio of ghrelin to leptin leads to increased eating and weight gain. Getting a good night’s sleep may be an important secret weapon to controlling your appetite and losing weight.
Ghrelin secretion also seems to switch off fat burning in muscle cells, changing the fuel source to glucose, at least in rats. This most likely occurs in humans as well. So if you just think about food , you may decrease your fat burning potential!
With weight loss, the amount of ghrelin secreted at meal time increases. This is the body’s attempts to restore the status quo and prevent starvation. Obese individuals secrete significantly larger amounts of ghrelin. If you are overweight, you may have a larger appetite and eat more because your ghrelin is talking to you. Your body is trying to keep you fat!
Ghrelin secretion can be affected by bariatric surgery. Gastric bypass procedures lead to low ghrelin secretion, which may account in part for some of the weight loss seen after these procedures. Low ghrelin leads to a reduced appetite. However, ghrelin secretion increases after gastric banding procedures.
To minimize your ghrelin secretion:
- Lose weight (less fat → less ghrelin)
- Get a good night’s sleep (7 – 9 hours/night)
- Avoid environmental triggers that stimulate appetite
- Avoid fantasizing about food; change your thought patterns
- Gastric bypass procedures lower ghrelin but gastric banding does not, and may actually increase it