Why Slow Eaters May Burn More Calories

People have been advising others to chew their food well for a long, long time. In Ayurveda, a school of medicine founded in India some 7,000 years ago, slow and thorough chewing is considered essential to strong digestive health, helping to separate a food's indigestible components from necessary nutrients.

People also flocked to the notion—some, fanatically—in the U.S. During the early 1900s, a self-proclaimed “economic nutritionist” named Horace Fletcher recommended chewing each bite to the point of liquefaction, then involuntary swallowing. “Fletcher was an efficiency buff, and was all about extracting the most from the least,” says science writer Mary Roach, author of Gulp: Adventures on the Alimentary Canal. “He wasn’t about 30 chews or something mild—he was talking about hundreds of chews per bite.”

Fletcher, who was not a doctor, believed that all that chewing helped the body get the most out of food. “His claim was basically that you could give the poor half the food, and if they chewed it more thoroughly they’d get more nutrients out of it,” Roach says. But her research didn’t turn up much evidence to back Fletcher’s theories. “Your stomach does a really good job of breaking down food and absorbing nutrients,” she says.

Eating more slowly while upping your chew count does not seem to make much of a difference, nutritionally speaking. But research suggests it may help control your appetite and weight gain.

Some preliminary research has found that chewing until “no lumps remain” increases the number of calories the body burns during digestion: about 10 extra calories for a 300-calorie meal. (Eating fast, on the other hand, barely burns any calories.) Chewing food more thoroughly also increases blood flow to the stomach and gut. By taking a little extra time for chewing, someone could theoretically burn about 2,000 extra calories each month, the study authors write.

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