Why Do Our Stomachs Growl?

By: Jessika Toothman | How Stuff Works

The human body is pretty amazing. Even if you don’t always hear them, your body is making all kinds of sounds while it works hard to keep you well. We’re talking about noises like your joints popping or even your stomach growling.

Speaking of your stomach growling, what exactly is going on there? Everybody’s belly chimes in from time to time. Whether you call it grumbling, gurgling or growling, these low rumbling noises sound like a pot of bubbling stew instead of your stomach. But the question is, why do our stomachs growl in the first place? What’s it trying to tell us?

Stomach Growling Post-Meal

The rumbling and grumbling we hear does originate in the stomach, but it also comes from the small intestine, so it’s good to start with a close look at how the digestive system works.

Our digestive system is, in essence, a long tube that starts at our mouth and ends at our anus. This tube connects the various organs and passages that play important roles in digestion. One of the most important things to know about the digestive system is how it propels food, which explains why we might hear noises after we’ve eaten.

Waves of muscle contractions push the food contents down our small intestines into our bowels in a process called peristalsis. These contractions help churn food, liquid and different digestive juices together, rendering them into a gooey mix known as chyme. The sounds we hear — our stomach growling — are from moving those solid and liquid ingredients, plus gasses and air.

The Hungry Stomach Growling

Your stomach can growl at any time — not just after you’ve eaten — but when there’s food in your stomach or small intestine, the growling is less obvious. It’s like when you put a pair of sneakers in the dryer by themselves versus with a load of towels. The towels muffle the noise of the shoes as they bounce around.

But if you’re hungry and your stomach is empty, that’s when you notice your stomach growling the most. Are those same muscle contractions that digest food to blame here as well? Sort of.

When your stomach is empty, your brain releases an appetite-stimulating hormone called ghrelin. It signals the digestive muscles to restart the process of peristalsis, or to contract. This is again the rumbling you hear.

But why? Two reasons: First, those contractions are “sweeping up” any food bits they might have missed the first time around. Second, those vibrations and rumblings of your empty stomach are designed to make you hungry. The muscle contractions will come and go about every hour until you eat again.

In some cases, of course, excessive grumbling could be a sign of an upset stomach, but you shouldn’t be too concerned unless the sounds include cramping, nausea, vomiting or constipation.

So now that we know what causes stomach growling, is there any way to control it? One tip to mute a noisy belly is to eat many small meals instead of a few large ones. Your digestive system will have less opportunity to create those peristalsis rumbles if your body has something tasty in it. Also, eating fewer foods that cause gas may help decrease the growling.

Now That’s Interesting

The medical term for the sounds your body is making is as it digests foods is borborygmi (borborygmus is the singular form). The term comes from the Greek word borborugmos, an example of onomatopoeia (a word created to imitate a sound). Borborygmi illustrates what stomach growling might sound like in word form.

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