If you’ve been trying to lose a few stubborn pounds and finding that diet and exercise just aren’t doing the trick, a new study in the journal Diabetologia suggests there may be one quirky trick that might make a difference: How you’re using your indoor lighting.
Looking at 14 overweight men and women between the ages of 40 and 75, researchers had participants stay in a special indoor chamber that measured respiration rates for 40 hours. That measurement allowed them to determine factors like how quickly and when they were burning calories, both while awake and sleeping.
The time was broken into two separate sessions based on light exposure. One mimicked natural light with a bright day and dim evening, while the other flipped that sequence. In both sessions, participants were in darkness during the night and had regular meals that kept calorie and macronutrient content consistent.
Blood samples were taken before breakfast and dinner, then at 30-minute intervals in the four hours after both meals to determine triglycerides, insulin, melatonin, and glucose levels. All of those play a role in metabolism, according to lead author Jan-Frieder Harmsen, in the nutrition and movement science department at Maastricht University Medical Center in the Netherlands.
The study found that spending the day in bright light led to lower blood glucose levels before dinner compared to spending the day in dim light. By contrast, having bright light in the evening led to a reduction in sleeping metabolic rate, which means participants were eating the same amount but burning fewer calories as they slept.
While spending more time outdoors is always a good idea, Harmsen tells Eat This, Not That! that you don’t necessarily have to rely on outside lighting to get the benefits of the correct day-evening mix.
“Redesigning indoor lighting conditions so they mimic the natural light and dark cycle holds promise to improve metabolic health,” he says. “At the least, avoiding bright light in the evening can affect your glucose metabolism in significant ways that reduce risk of weight gain.”
To learn more about light and metabolism, check out Avoiding This One Thing Before Bed Can Help You Burn More Fat, New Study Says.