Night owls may have more belly fat, higher blood sugar, poorer lipid profiles: Study

Night owls, who tend to consume foods high in energy, carbohydrates and fats late at night, could be associated with a greater body fat percentage, belly fat, and higher blood sugar and lipids, according to a study.

“Chronotypes influences our preferences for food intake, our behaviours and our metabolism,” author Rozanne Kruger, from Griffith University’s school of allied health, sport and social work, said.

“Both Morning-types and Evening-types consumed similar amounts of food or energy across the day, but it was the timing of eating that was crucial,” Kruger said.

The study, published in the journal Frontiers in Nutrition, looked at 287 European and Pacific New Zealand women aged 18-45 years and assessed if they were morning chronotypes (early bird) or an evening chronotype (night owl).

Evening-types consumed less food between 3 am and 9:59 am but more food between 8 pm and 2:59 am, while the opposite was true for morning-types.

Night owls were more likely to consume lower energy and protein intakes in the morning, and ate foods that were high in energy, carbohydrates and fats late at night.

“The ET (evening types) women consumed less energy and less micronutrient-dense food than the MT-IT (morning types and intermediate chronotypes),” the authors wrote.

“The ET had lower dietary intake in the morning but higher intake in the evening, with an inverse pattern observed among MT-IT. Higher energy and macronutrient intake in the evening was significantly associated with a higher BF% (body fat per centage) and AG (android-to-gynoid) ratio in ET, suggesting a potentially greater susceptibility to obesity,” they said.

Consuming food at night, when we are supposed to be fasting and sleeping, means we store more food rather than use it, which may increase susceptibility to obesity and cause worsen health outcomes, the authors explained.

The women who naturally preferred a later bedtime and wake time were also more likely to have poorer lipid profiles, and less favourable indicators of glucose regulation, compared to morning-types.

“The research highlights that when people eat may be just as important as what they eat. Targeting meal timing, particularly reducing late-night eating, could be an important strategy for improving health amongst people with an evening chronotype,” Kruger said.

“It reinforces the role of chrononutrition and the role it plays in obesity and metabolic disease prevention,” the author said.