Japanese researchers found a link between eating speed and weight gain. They interviewed almost 60,000 type 2 diabetes patients about their eating habits and then analyzed the data.

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The satiety mechanism

When people eat too fast, hormones in the gut that relay the “I’m full” signal to the brain aren’t given enough time to work. This means you’ll eat more food, falsely believing you aren’t full yet. More calories result in weight gain.

As partially digested food enters the small intestine, a series of hormones are released into the bloodstream. Cholecystokinin (CCK), is released by the intestines in response to food consumed during a meal. Leptin, another hormone implicated in satiety, is an adiposity signal that communicates with the brain about long-range needs and satiety, based on the body’s energy stores. Research suggests that leptin amplifies the CCK signals, increasing the feeling of being full. By eating too fast, people may not give this intricate hormonal system the needed time to tell the brain that the stomach is full.

Eating slower lowers obesity development

Study authors Haruhisa Fukuda and Yumi Hurst of Kyushu University Graduate School of Medical Sciences in Fukuoka, Japan, confirm this hypothesis in their paper published in the journal BMJ Open.

Researchers measured the participants’ Body Mass Index (BMI) and waist circumference. Obesity is defined as 25 or more BMI points. Next, the participants answered a set of questions about their eating speed (‘fast’, ‘normal’ and ‘slow’), whether they had dinner within 2 hours of sleeping, but also habits concerning after-dinner snacking, skipping breakfast, alcohol consumption frequency, sleep adequacy and tobacco consumption.

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The results showed that 21.5% of the slow-eating group was obese, compared to almost 30% of the normal-speed eaters and 45% of the fast-eating group. Slow eaters had an average BMI of 22, normal eaters had a BMI of approximately 23.5, and fast-eaters had an average BMI of 25. Waist circumference was found to be directly proportional to eating speed as well.

No sleep loss, not skipping breakfast and not eating dinner two hours before bed were all associated with a lower BMI.

This is an observational study because researchers did not measure calory intake and physical activity, which could have affected the results in an unknown manner.

Also, the terms ‘fast’, ‘normal’ and ‘slow’ were used by the participants of this study just as a self-evaluation, without a strict definition of the eating speeds, and without timing the participants while eating.

The verdict: eat slow and enjoy your meals, stop living your life on fast forward and take your time to savor the delish in your dish.

“Interventions aimed at altering eating habits, such as education initiatives and programmes to reduce eating speed, may be useful in preventing obesity and reducing the risk of non-communicable diseases,” the authors conclude.

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