When humans get hungry, our stomachs appear to protest with a series of rumbles and growls that can be audible even to those around us. It’s a normal part of being human and something all of us have experienced, but what’s actually going on to make those peculiar sounds?
The reason why our stomachs growl when we’re hungry is because of the hormonal feedback that tells us that we need to eat, and also how the musculature of our digestive tracts contracts and relaxes. The rumbling and gurgling sound it makes even has its own fun name: borborygmus, which means rumbling in Greek.
Why does your stomach growl when you’re hungry?
There are four key explanations as to why your stomach growls when you’re hungry – or gets its borborygmus on, as we’ll be saying from now on.
Muscular movements
Smooth muscles line most of the gastrointestinal tract in bundles that can contract and relax to help food move in the right direction. If you imagine the series of tubes a meal has to move through sort of like sausage casing, you need a squeezing motion to keep solids moving forwards, and that what’s your muscles do. The scientific word for that squeezing motion is peristalsis, and it happens rhythmically to keep everything moving along.
As well as pushing food around, those muscular contractions can move gas and liquids, so you can imagine the kinds of sounds combining all three creates. The rumbling sounds from muscular contractions aren’t limited to the stomach, either, and often the noises you’re hearing are coming from lower down in the intestines.
An empty stomach
Part of the reason why rumbling seems to be so loud when we’re hungry is that at this time your stomach is empty. Food is a good muffler of sound, so when your food tube is empty, its muscular activity gets noisier even though it’s not doing anything that differently from normal.
Hormonal feedback
Hormones help us to keep track of our need for nutrition in the form of ghrelin and leptin. Ghrelin tells us we’re hungry, while leptin tells us we’re full. Some animal studies have shown that ghrelin may increase gastric motility and emptying, and a study on humans found giving participants ghrelin got their gut moving faster compared to saline.
It’s possible, then, that when we get hungry, ghrelin may increase the muscular movements that give rise to borborygmi, but it’s a complex part of our physiology involving many hormones that we still don’t entirely understand.
Do stomachs only growl when you’re hungry?
No! There are a lot of things our guts need to clear, including mucous, gas, and fluids, so peristalsis is constantly working to keep things moving so that we don’t experience a build-up of anything. As anyone who’s experienced severe gas could tell you, build-ups can be very painful and in the case of blockages and volvuli (when the intestine twists), people can require emergency surgery.
Never was this demonstrated more than in the case of a fecal impaction that caused a man to lose the ability to walk and develop life-threatening abdominal compartment syndrome when “approximately 2 liters” of feces got stuck. Yikes.
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The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.
