Open the curtains to help your BMI.
The next time you run in the morning because you’re late for work, it may be worth opening the curtains and allowing sunlight to enter. Why? Because dressing in the dark may be why you have a hard time losing weight.
In a study published in PLOS One, researchers at Northwestern University had 54 adults wear wrist monitors to record their light exposure and sleep habits for a week. Participants also kept a record of what they ate so that the researchers knew their caloric intake.
After taking into account activity level, age, calorie intake, season of the year, and sleep habits, the researchers found that participants who were exposed to light earlier in the day had a body mass index ( BMI) lower. They also found that for every hour of delay in light exposure, BMI increased by 1.28 points.
What could this mean for you in practical terms? The researchers recommend obtaining? 500 lux? of light (roughly the equivalent of your office lighting) as early as possible when you wake up in the morning. An easy way to get 1000 lux is to train outdoors, but just opening the curtains helps.
Previous studies have shown that exposure to light can affect your circadian rhythm, which can influence everything from your sleep habits to your appetite levels, so it is understandable that it can impact your weight as well. Finally, you may not lose five kilos immediately, but some sunlight in the morning will not affect you.