Ghrelin: How the Hunger Hormone Works

What is ghrelin and should you take a ghrelin blocker to lose weight?

Ghrelin the hunger hormone
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Ghrelin is a hormone that is produced by the stomach when it is empty. Ghrelin travels through the bloodstream to the brain where it stimulates neurons in the hypothalamus to signal hunger. For this reason, ghrelin is often called the "hunger hormone." But researchers now know that ghrelin has many other functions in the body.

What Is Ghrelin?

The definition of ghrelin as a hunger hormone may oversimplify its role in the body.

Ghrelin does send hunger signals to your brain so that you want to eat. But ghrelin has many other functions in your body as well. 

When there is no food in your stomach, it releases the hormone ghrelin. Scientists know this because ghrelin levels are highest right before you eat. Ghrelin travels through the bloodstream to a part of your brain called the hypothalamus. The hypothalamus regulates hunger, thirst, mood and other physical functions.

When ghrelin receptors in the hypothalamus interact with the hormone, it sends a strong signal to your body that the food supply is low and you need to eat. Then you start to feel hungry and other changes occur in your body.

  • You start to conserve fat. Researchers know that ghrelin signals the body to decrease brown fat thermogenesis and oxidation in your fat cells. That means that your body is burning fewer to save energy in case of starvation.
  • The stomach becomes more stretchy. Scientists know that ghrelin increases "gastric motility" to help prepare your stomach to accept food and push food through the digestive tract.
  • Your appetite increases. Your brain continues to send signals that you are hungry until you start to eat. After you eat, ghrelin levels decrease for 1-3 hours.

So what else does ghrelin do? Recent studies have found that in addition to its job as a hunger signal, the hormone also helps to regulate glucose and insulin, may boost heart health, helps to protect bones and muscle, and may even help protect against cancer.


How to Change Your Ghrelin Levels

Even though ghrelin may provide benefits in your body, many dieters are still frustrated by nagging hunger pangs and would like to reduce ghrelin to feel better. So is it possible to block ghrelin so that you eat less? Here's what the evidence says about your ghrelin in your body:

  • Poor sleep increases ghrelin. Studies have shown that when you don't get enough sleep, ghrelin levels increase. So you can get a good night's sleep to help to block ghrelin in your body. Sleep may also help you to produce more leptin - a hormone that helps you to eat less. Leptin and ghrelin work together to help you eat the right amount, but when you're trying to lose weight dieters usually want to increase leptin.
  • An empty stomach stimulates ghrelin. Since ghrelin production starts when your stomach is empty, you may be able to limit ghrelin by eating small snacks or meals throughout the day. But if weight loss is your goal, try to choose diet-friendly snacks that help you create a calorie deficit.

So should you take a diet supplement or ghrelin blocker to change the hormone in your body? Probably not. Most of the supplements are filled with herbs to help you feel full so that you don't respond to hunger signals and you eat less food. But you don't need an expensive supplement to feel full. Fiber-rich foods provide the same benefit for less money (and they taste good too!)

So what's in the future for hunger hormones like ghrelin? Researchers continue to study the different ways that many hormones interact to control your weight. But most have said that it will be years before the hormones will be used to help you slim down. In the meantime, most experts continue to recommend common sense approaches to losing weight. Eat healthy, calorie-controlled meals throughout the day, get plenty of physical activity and talk with your doctor if traditional methods don't work.


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