Listening to the Language of the Gut

Aug. 20, 2008— -- It may happen in the middle of a meeting or simply while sitting around with friends: that low, rumbling sound that lets you -- and everyone around you -- know that you're hungry.

But is that occasionally embarrassing growling noise really signaling hunger, or is it caused by something else?

Tragically, in the vast swaths of funding for health and nutrition research, it doesn't appear that much (if any) money has been spent attempting to decipher once and for all what may be the world's most widely spoken language.

"A rumbling stomach cannot be assumed to mean your body needs food," said Dr. David Katz, director of the prevention research center at Yale University School of Medicine. "Your stomach speaks an ancient language, so it requires some thoughtful interpretation before you rush to conclusions -- or the fridge."

Katz explains that those noises from your middle may have a variety of causes.

"An empty stomach can be triggered to rumble by the hormones that regulate appetite, among them leptin and ghrelin. So a stomach will rumble when hunger sets in."

"It will also rumble after eating, at which time the churning is about digestion, not ingestion," he said.

"Finally, a very appetizing aroma can elicit an appetite response that has nothing to do with hunger, per se. The responses can range from the proverbial salivation to stomach rumbling. But this does not mean your body 'needs' food," he said.

Katz said those rumblings probably evolved in a period when food was not readily available. While calories might be plentiful in the modern-day United States, it seems stomachs still want to speak up and be counted.

The various growling sounds seem to have a few causes. The common rumbling of our stomachs, according to Katz, is caused by bands in the stomach, called rugae, that contract in order to help digest food.

Others place the source of some noises in the intestines.

"What you are hearing is the movement of your intestines and the passage of gas through them -- a totally normal process," said Dr. Roshini Rajapaksa, a gastroenterologist at NYU Medical Center.

In addition to those identified by Katz, she added an additional potential source for your digestive system's need to communicate.

"Growling may be caused by other things, like an infection, which causes excessive intestinal movement," she said.

However, when stomach growling is a sign of something more insidious, it is typically accompanied by more specific symptoms, so anyone listening to their body's signals probably has little to fear from just the rumbling.

"In this case," Rajapaksa said, "the growling may be accompanied by diarrhea."

Dr. Joel Weinstock attributes much of the noise to the small bowel and colon.

"There is gas and liquid in our intestines. The intestine frequently contracts in a rhythmic way to propel food down the [gastrointestinal tract]," he said. "When this contraction process is somewhat forceful, we frequently hear a sound as air and water are squeezed around sharp turns or narrow constrictions in the gut."

Taming Your Tummy

As to how to avoid those sometimes embarrassing noises, dietitian Keith-Thomas Ayoob of the Albert Einstein College of Medicine has a few suggestions for how to interpret the sounds.

"It may mean that the food you ate just left your stomach quickly. It doesn't necessarily mean that you need calories," he said.

"That's why having food that 'sticks to your ribs' [like fiber, protein, some healthy fats] will keep your stomach full for a while longer than an easily digested meal [like low-fiber carbs or just liquids like juice and coffee] and that stomach won't contract too quickly."

Ayoob said that in the end, the type of food may affect your growling more than how much you ate.

"You can eat a lot of calories that leave the stomach quickly. [It] doesn't mean you need more calories, it may mean that you need better calories," he said.

Ultimately, those stomach noises may just mean different things in different people -- and hopefully you know what your stomach is trying to tell you when it growls.

"Stomach and intestinal noises occur because of movement within the digestive tract," said Connie Diekman, director of university nutrition at Washington University in St. Louis and past president of the American Dietetic Association.

"This can be due to movement of food after a meal or due to hunger. So, bottom line is that people need to know their bodies and learn how their bodies signal them to eat, since noises are just one possible part."

So while your stomach may be speaking a little too loudly for a private conversation, it may just be trying to get its message across.