Snacking specifically at night increases risk of diabetes, weight gain, study finds
Snacking in the evening might seem harmless, but it goes against the body’s natural biological rhythm. People who stop the habit may lower their risk of diabetes and shed some weight, according to new research.
Han Jiao of the Netherlands Institute for Neuroscience made the discovery as part of her PhD research. The study, conducted on male rats, gave one group access to food all day while a second group could eat only within a limited time window. The rats that ate during their active period — nighttime for the animals — stored significantly less fat.
Andries Kalsbeek, Jiao’s research supervisor, said the findings trace back to the body’s internal clock. “The biological clock is located in the brain and controls our sleep rhythm and eating behavior,” Kalsbeek told RTL. “The problem is that its rhythm isn’t exactly 24 hours. Every day, that clock needs to be reset.”
Light is the most important signal for resetting the clock. When the eyes detect morning light, the body knows it is daytime — the period to take in and burn energy. In darkness, the body shifts into “rest mode,” when food is not processed as efficiently.
“Our body works best when it is in sync with the biological clock, which expects us to be active during the day and rest at night,” Kalsbeek said. He added that physical activity is also most beneficial during daylight hours. Because daylight lasts longer in summer, the body’s active phase extends slightly.
Humans would benefit most from a 16-hour fasting window, but Kalsbeek said that is difficult for most people to maintain. He recommends a more realistic fasting period of 10 to 12 hours.
The biggest benefit of daytime eating is improved blood sugar control, which lowers the risk of diabetes. Some people also experience weight loss, though results depend on what and how much they eat.
Kalsbeek said one of his colleagues, Chun-Xia Yi, used her own husband as an informal test subject. The man frequently snacked in the evening and had high blood pressure and cholesterol.
“Within a few days after he stopped evening snacking, his blood sugar levels returned to normal,” Kalsbeek said. “After a month, he had lost three kilograms.”
