How the Hunger Hormone Ghrelin Works

Ghrelin is a hormone that is produced by the stomach when it is empty. Ghrelin travels through the bloodstream to the brain, stimulating 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 the 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. It also acts on the amygdala, the part of the brain responsible for reward processing. Ghrelin causes the pituitary gland to secrete growth hormone, which breaks down fat tissue and causes muscle to grow.

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 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.

How to Change Your Ghrelin Levels

Although ghrelin may provide benefits in your body, many people 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. 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 people 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.
• Protein foods may help block ghrelin. One small study published in 2008 showed that foods higher in protein suppressed ghrelin levels for a more extended period. Lean proteins are a smart choice for people who want to build a more muscular, leaner body.
• Weight loss increases ghrelin. People who have lost weight have higher ghrelin levels than people who have kept the same weight for years. Try to maintain a stable, healthy weight to keep ghrelin levels under control. 

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 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!)

A Word From Verywell

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 slim down. In the meantime, most experts continue to recommend common-sense approaches to lose 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.