Want to Eat Healthier? Listen to Your Biological Clock

The jury’s still out on whether early birds are superior to night owls, but they may have an easier time maintaining a healthy lifestyle. As The New York Times reports, a new study published in the journal Obesity found that morning people may make better food choices, and eat earlier in the day, than those who function on an evening schedule.

Finnish researchers wanted to see whether a person’s chronotype—their personal biological clock—affects their eating habits. To do so, they examined data from 2000 men and women who participated in Finland’s national FINRISK and FINDIET studies in 2007. The first study monitored participants' health-related behaviors; the second, their dietary habits.

For the FINDIET study, the subjects logged their food and alcohol intakes for 48 hours, tracking their daily caloric intake and the types of macronutrients they consumed. They also recorded when they ate, both during the week and during the weekend. The FINRISK study looked at participants’ sleep habits; this helped researchers determine whether participants were morning or evening people, CBS News reports.

After crunching the numbers and controlling for various factors (age, sex, BMI, education, etc.), the researchers found that morning people and evening people consumed similar amounts of calories per day. However, the night owls tended to eat fewer calories in the morning—and when they did eat, they chose breakfast foods that were higher in carbs, fats, and sugars. The night owls also ate more sugars and fats during the evening.

This difference was even more pronounced during the weekend: Night owls consumed far more sugar and fat than the early birds, they ate more, and they also ate during irregular times, researchers noted.

"Early birds may have an extra advantage over night owls when it comes to fighting obesity as they are instinctively choosing to eat healthier foods earlier in the day," concluded Courtney Peterson, a nutrition sciences professor at the University of Alabama at Birmingham, in a press release. "Previous studies have shown that eating earlier in the day may help with weight loss and lower the risk of developing diabetes and heart disease,” Peterson added. “What this new study shows is that our biological clocks not only affect our metabolism but also what we choose to eat."

You may be able to make better lifestyle choices if you know your chronotype, Peterson added. "Clinicians can help steer people to healthier options—and suggest the optimal time to eat these foods—based on what we now know about our biological clocks," she said.