Obesity Prevention? Simple, Just Chew More Slowly

Can obesity prevention be as simple as telling people to chew more slowly? That’s what the principal investigator of a new study published in Nutrients, Professor Katsumi Iizuka, says:

“These are easy, money-saving measures that can be started right away to help prevent obesity.

“Incorporating the proposed eating behavior into school lunches and other programs can lead to the prevention of future diseases related to obesity.”

But No Data on Obesity or Prevention

The study behind this advice is neither randomized nor controlled. It involved only 33 healthy individuals in Japan with an average BMI of 23. There is no data in this study on obesity or its prevention – only data on asking people to chew more slowly and the rate of chewing that results.

The study had four segments. At first, subjects received a quarter slice of pizza, wore headphones to block outside sounds, and ate the slice. Researchers measured the chewing duration, tempo, chews, and bites. Next, they consumed another quarter slice while listening to a metronome tempo of 40 beats per minute. Each participant subsequently ate a slice with a metronome at 80 bpm and then 160 bpm.

The findings were simple and unsurprising. With faster chewing tempos, meal duration was shorter and subjects required fewer bites and chews to finish. In other words, the faster they ate, the more they gulped their food down with bigger bites. Men took fewer bites, chewed less, and finished faster. But their chewing tempo was not different from women.

Good Advice That Might Not Prevent Obesity

This is a fine example of a study of advice for good eating habits. But it tells us nothing about preventing obesity. Sure, if you are willing to assume that eating more slowly will prevent overeating, and you think of obesity as merely the result of bad eating habits, then you can tell yourself, this ought to work!

But in fact, we have no evidence that it will. It might help a person enjoy their food and be more mindful about how much they’re eating. But behavioral interventions like this typically have a minimal impact on obesity risk.

That’s because obesity is mostly driven by the interaction of a person’s biology with their environment. Not by bad behavior.

So no. There’s no evidence here that having people chew slowly is an effective way to prevent obesity.

Click here for the study, here for the press release, and here for other misreporting on this work.

Chew on This, photograph by xlibber, licensed under CC BY 2.0

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April 23, 2025