I learned two things when I was working at McDonalds years ago as a teenager. One, young women aren’t impressed with free Big Macs and Super-Sized Fries. You may be able to turn lemons into lemonade, but you definitely can’t flip hamburgers into dates.
As for the second teaching point, some people eat fast as (pick any expletive). I’m not judgmental—but finishing a super-sized value meal while sitting in drive-thru waiting for me to fill a cup with pop is objectively fast by any standard. Have you ever seen the movie Coneheads? I’ve seen the real-life version of the scene below.
Although eating this fast is great for Hollywood magic, a recent study in BMJ Open showed that eating too fast may make it easier to gain weight.
Does eating too fast really affect our weight? See what one study says.
Whenever people focus on losing weight or preventing weight gain, we tend to only focus on what we eat. Ketogenic diets, plant-based diets, low-fat diets—the conversation typically stops with food (check out my post about foods associated with weight gain and weight loss). How quickly we eat is little more than a fleeting afterthought. Based on the study above, we may want to pay a little more attention to how fast we eat. Before you tell everyone to count how many times they chew their food or start handing out stopwatches at the dinner table—let me break down the study’s findings.
The study looked at almost 60,000 people with diabetes in Japan who had health check-ups from 2008 to 2013. The Japanese Ministry of Health, Labor, and Welfare introduced the health check-up program to identify risk factors for weight gain in response to an increasing prevalence of people with excess weight. During these check-ups, screeners asked people questions about their eating and sleeping habits. The screeners focused on how fast people ate—categorizing people as fast, normal, or slow eaters. They also assessed the frequencies of skipping breakfast, snacking after dinner, and eating 2 hours before sleeping.
The researchers found that slow eaters were significantly skinnier than the faster eaters. In fact, they found that slow eaters were 42% less likely to suffer from obesity than fast eaters. Similarly, regular speed eaters were 29% less likely to be overweight. Significantly more women were slow eaters compared to men. Overall, 22,070 people ate like the Flash; 33,455 people ate at an average speed; and 4192 ate mindfully and slowly.
The researchers also found that eating snacks after dinner and eating within 2 hours of sleeping at least three times per week were both associated with a higher body mass index (BMI). Interestingly, the researchers did not find an association between skipping breakfast and weight gain—I still advocate for eating breakfast.
What are my two cents about eating fast and weight gain?
The findings aren’t surprising to me. Prior studies have linked eating too fast with blood sugar issues and weight gain. Although no one has clearly explained how eating fast leads to weight gain, the connection is likely due to the possibility that quick-eating creates more of an opportunity to take in more calories before your body recognizes fullness or satiety. Even competitive eaters recommend trying to maintain a fast pace and avoid slowing down.
It’s also not surprising to me that people who ate late at night or had after dinner snacks had higher weights compared to those who didn’t. Due to our circadian rhythms, the human body isn’t geared towards eating late at night—we aren’t nocturnal creatures.
What’s the bottom-line about eating fast and weight gain?
Ultimately the authors of the study concluded, “Changes in eating habits can affect obesity, BMI, and waist circumference. Interventions aimed at reducing eating speed may be effective in preventing obesity and lowering the associated health risks.”
Sometimes eating fast is necessary. Trust me, as a resident physician, I’ve seen people finish meals while running to patients’ rooms for a code blue cardiac arrest. This study shows that you shouldn’t make eating fast a habit.
Also, based on this study, I don’t recommend eating late at night or snacking after dinner.
If you are concerned about gaining weight or if you’re trying to lose weight, this study shows that you not only ‘what you eat,’ but also ‘how you eat.’
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I am a physician and trained chef. I specialize in gastroenterology and nutrition. Currently I work as the Associate Director of Adult Nutrition at the University of Chicago.