You may have stood in front of an open refrigerator late at night and thought, “This isn’t a good idea.” And a recent scientific study from Brigham and Women’s Hospital in Boston agrees—eating late isn’t good for you. In fact, the study in Cell Metabolism concludes that it can increase a person’s risk for obesity.
According to the study, obesity affects 42 percent of the U.S. population. In turn, obesity can contribute to chronic diseases such as diabetes and cancer. This new study followed 16 participants, all classified as overweight. The researchers focused on three factors and how they’re affected by eating late: the regulation of calorie intake, the number of calories burned, and molecular changes in fat tissue.
“In this study, we asked, ‘Does the time that we eat matter when everything else is kept consistent?’ And we found that eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat,” said author Dr. Nina Vujovic, a researcher in Brigham’s Division of Sleep and Circadian Disorders, in a press release.
Eating Late: What the Study Revealed
The study had two laboratory protocols. In one, participants had a strictly scheduled early meal, in the other, they ate four hours later.
When participants ate later, levels of the hormone leptin, which signals satiety or “feeling full,” were decreased. In addition, later eaters also burned calories at a slower speed. On a molecular level, the study found an increase in fat development and accumulation and a decrease in fat breakdown in the late eating participants.
With only 16 participants in total, this is by no means a large study. In addition, all participants had a BMI (body mass index) that was considered overweight or obese. It’s unclear if the findings would hold up across a larger sample size, or for people who aren’t overweight.
Despite those limitations, the data is compelling: At both physiological and even molecular levels, the study does show a possible connection between late eating and increased obesity risk.
Next time it gets late and you’re feeling peckish, it’s worth remembering it’s not only what you eat that matters—when makes an enormous difference, too.
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