Ghrelin, The Hunger Hormone Part 1

Last semester I wrote a paper on ghrelin, a hormone that I learned about during my rotation at the Tufts Weight and Wellness Center.  Here's Part 1 from my paper!

flickr photo from Mountainbread

Listen.  Can You Hear Your Hunger Hormone?

When was the last time you were hungry?  Maybe your stomach, with no thought to proper etiquette, interrupted you mid-sentence with an embarrassing gurgle.  Or maybe your stomach has not had a chance to rumble at all in recent days.  In the modern world physical hunger is one factor among many (such as social environment, convenience, and emotion) that regulates your appetite.  But take away the distractions, imagine complete silence, and you will hear the voice of your hunger hormone—ghrelin.  Scientists know that ghrelin sends hunger signals to the brain, and they are investigating its role in weight management.  Most importantly, ghrelin is your body’s natural hunger messenger.  You can benefit if you learn to listen and eat by its call.

Ghrelin’s Message: Eat food, now.

            Discovered in 1999 by Japanese scientist Masayasu Kojima, ghrelin is the only hormone that prompts hunger.  When your body physically needs food, your stomach and small intestine produce ghrelin.  Ghrelin then travels from these organs and binds to receptors in the hypothalamus.  There, it shouts its hunger message—and your brain responds with a series of hormonal reactions, ultimately prompting you to take that first bite of crunchy apple.             

As food enters your digestive system, ghrelin production decreases; research shows that protein and fat seem to stop it faster than carbohydrate.   Ghrelin production will stop altogether when other hormones enter the digestive system to break down food.  After the meal, levels of leptin and insulin (ghrelin’s counterparts) increase to make you feel full.  

coming next in Part 2: Lessons from ghrelin, and it's role in weight loss?