Excerpt of Mary Roach’s Gulp: How many times should you chew a bite of food?

The Health Fad That Had Henry James, Franz Kafka, and Arthur Conan Doyle Chewing Like Lunatics

The Health Fad That Had Henry James, Franz Kafka, and Arthur Conan Doyle Chewing Like Lunatics

What to eat. What not to eat.
April 10 2013 12:00 AM

How Many Times Should You Chew Your Food?

For maximum efficiency, according to one of the original crackpot health fads, hundreds and hundreds of times.

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Van Someren presented a paper at a meeting of the British Medical Association in 1901, and again at the International Congress of Physiology. Skeptical but intrigued, well-placed scientists at London’s Royal Society and at Cambridge University and Yale’s Russell Chittenden undertook follow-up studies, with mixed conclusions. In 1904, 13 lads of the Hospital Corps Detachment of the U.S. Army were taken away from their nursing duties for six months to serve as guinea pigs in a test of Fletcher and Chittenden’s low-calorie, low-protein, super-mastication regimen. Here there was no strapping lad in knickers and feathered felt hat to do the weighing and tidying up. The men’s work began at 6:45 a.m. with an hour and a half of “duties about the quarters, such as ... assisting in measurement of urine and faeces and transportation of the same to the laboratory; cleansing of faeces cans and urine bottles, etc.”

Chittenden claimed to have evidence that the Fletcher system enabled a man to get by on two-thirds the calories and one-half the protein recommended by the current nutrition guidelines. Though the claims were roughly critiqued and largely dismissed by other scientists, they struck a chord with victualers: military officers and others whose jobs entailed feeding hungry hordes on limited budgets. In the United States and Europe, administrators at workhouses, prisons, and schools flirted with Fletcherism. The U.S. Army Medical Department issued formal instructions for a “Method of Attaining Economic Assimilation of Nutriment”—aka the Fletcher system. (“Masticate all solid food until it is completely liquefied,” begins the familiar refrain.) In 1917, Chittenden   became a scientific advisor to Herbert Hoover, then the head of the U.S. Food Administration. Fletcher, living in Belgium during World War I and already chummy with the U.S. ambassador there, parlayed these two connections into his gig as an “honorary alimentary expert” for Hoover’s relief commission. Together, he and Chittenden did their best to convince Hoover to make Fletcherism part of U.S. economic policy, thereby justifying a two-thirds reduction in the amount of civilian rations shipped overseas. Hoover sagely resisted.

Fletcher’s true colors could occasionally be seen through the seams of his cream-colored suits. After bragging, in a 1910 letter, that a family of five could save enough money to furnish a five-room flat in 15 months by Fletcherizing, he adds, “Of course, the furnishings must be of the simplest sort.” This from a man who lived for years in a suite at the Waldorf Astoria. He summed up his policies at the end of the letter: “Expert economics coming to the assistance of ambitious unintelligence.” Let them chew cake.

In 1979, a pair of Minneapolis researchers put Fletcherism to the test. They brought 10 subjects to the local Veterans Administration hospital and purchased some peanuts and jars of peanut butter. The subjects first ate a diet in which almost all the fat came from peanuts. The peanuts were then swapped out for the peanut butter—an aesthetically acceptable stand-in for excessively chewed peanuts. The subjects’ “digestion ash,” as Fletcher liked to call excrement, was then analyzed to see how much of the peanut fat was leaving the body unabsorbed.

“ ‘Nature will castigate those who don’t masticate’ may hold some truth,” concluded the paper, which appeared in the October 1980 issue of the New England Journal of Medicine. On the whole peanut diet, the subjects excreted 18 percent of the fat they’d consumed. When they switched to peanut butter, only 7 percent escaped in their stool.


But peanuts are hardly representative of the average food. Everyone knows—via “visual observation of stool samples,” to use the New England Journal of Medicine’s way of saying “a glance before flushing”—that chunks of peanuts make their way through the alimentary canal undigested. Nuts are known for this. Peanuts (and corn kernels) are so uniquely and reliably hard to break down that they are used as “marker foods” in do-it-yourself tests of bowel transit time—the time elapsed between consumption and dismissal. (The human digestive tract is like the Amtrak line from Seattle to Los Angeles: Transit time is about 30 hours, and the scenery on the last leg is pretty monotonous.) 

Peanuts are the food singled out for this trait by Martin Stocks, business development manager for the Model Gut, a computerized tabletop digestive tract that can be hired out for absorption studies. I had contacted Stocks to see if it might be possible to engage the Model Gut for a test of Fletcherism. It was, but would “likely run into the $10,000 to $20,000 range.” Stocks’s opinion was that with a few recalcitrant foods—here he singled out nuts and rare or raw meat—extensive mastication (chewing) might make a small difference in how much energy and nutrients are absorbed, but that it was “unlikely to have a dramatic effect on one’s overall nutritional intake.”

Stocks passed my email along to Model Gut senior scientist Richard Faulks. Faulks was dismissive not only of extreme chewing, but also of the related fad for blenderizing to increase the accessibility of nutrients. Its true saliva carries an enzyme that breaks down starch, but the pancreas makes this enzyme too. So any digestive slack caused by hasty chewing would be taken up in the small intestine. The human digestive tract has evolved to extract the maximum it can from the food ingested, Faulks said, and that is probably all it needs. “Nutritional science is dogged by the idea that if some is good, more is better,” he said, “and this has led to the belief that we should endeavor to extract as much as possible of whichever fashionable component is in vogue. This is to ignore evolutionary biology and the imperative of survival.” He pretty much ran Horace Fletcher through the Model Gut.

One thing to be said in favor of thorough chewing is that it slows an eater down. This is helpful if that particular eater is trying to shed some weight. By the time his brain registers that his stomach is full, the plodding 32-chews-per-bite eater will have packed in far less food than the five-chews-per-bite wolfer. But there’s thorough and there’s Fletcher. Chewing each bite, say, 100 times, Faulks said, could have the opposite effect. It would lengthen the meal so radically that the stomach could have time to empty the earliest mouthfuls into the small intestine, while the last mouthfuls are still on the table. Thereby making room for more. Fletcherizers’ meals could conceivably be so interminable that by the time they finally cleared their plate and set down their napkin, they’d already be feeling peckish again.

Not to mention, the morning’s half gone. “Who has time for this?” was the reaction of Jaime Aranda-Michel, a gastroenterologist with the Mayo Foundation, when I called to ask him about Fletcherizing. “You’re going to spend all day just having breakfast. You will lose your job!”

Adapted from Gulp: Adventures on the Alimentary Canal by Mary Roach. Copyright © 2013 by Mary Roach. With permission of the publisher, W.W. Norton & Company, Inc.