It’s been hours since you last ate and your stomach growls. Have you ever wondered what’s making it groan?
According to research in the journal Nature Reviews, stomach noises are caused by the migratory motor complex or MMC for short. The MMC is a repeating cycle of powerful contractions that help push bits of food, bacteria, and other gastrointestinal debris into the colon, like a swallow reflex that spreads throughout the intestine.
MMC may be one of the most underestimated factors when it comes to the health of your digestive system.
“The migratory motor complex refers to recurrent contractile waves that travel through the gut,” says Emeran Mayer, MD, professor of medicine and founding director of the Goodman Luskin Microbiome Center at the University of California, Los Angeles.
Mayer says that the strength of these contractions is comparable to that of a nutcracker. They occur in cycles that last around 90 minutes and help ensure that any food molecules left over after a meal or snack are forced into the large intestine.
That’s not all they do. “The initial interpretation of this motor pattern was more like a bowel cleansing than anything else,” he says. “But today this has great relevance in terms of gut microbial habitat.”
Mayer is the author of The Gut-Immune Connection, a book about the role of the microbiome in immune function. He says that some gut bacteria produce molecules that turn off inflammation.
Other bacteria support the healthy functioning of the intestinal barrier. There is evidence that the action of the migratory motor complex may support the growth and positioning of these so-called “good” bacteria, reducing the presence of competing “bad” bacterial species.
Here’s the problem: the migratory motor complex only works when the stomach is empty. “The minute you take a bite of food, it shuts off,” says Mayer.
To make sure the MMC has enough time to do its job, a goal of 14 hours of zero-calorie food or drink is a good goal, he says. For example, you can avoid all calories between 8 p.m. and 10 a.m.
“The 14 hours without food intake would allow the MMC to kick in and not only cleanse the gut of any indigestible and unabsorbable food components, but also restore the normal proximal-distal gradient of gut microbial density,” He says.
The weight loss effects of intermittent fasting plans get the most attention. But the microbiome benefits of taking meal breaks could be even more significant.
“People always talk about these diets or cleansing regimens,” says Mayer. “Well, you have the best cleansing regimen built into your bowel if you leave it empty for 12 or 14 hours.”