Can Sun Exposure Help You Lose Weight?
Exposure to light in the morning rather than later in the day may be a good way to manage weight, new research shows.
The study, from Northwestern Medicine, found that the timing, intensity and duration of light exposure is linked to Body Mass Index (BMI).
“The earlier this light exposure occurred during the day, the lower individuals’ body mass index,” said co-lead author Kathryn Reid, research associate professor of neurology at Northwestern University Feinberg School of Medicine. “The later the hour of moderately bright light exposure, the higher a person’s BMI.”
The study took into account a person’s activity level, caloric intake, sleep timing, their age and the season in which they got the exposure.
“Light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance,” said study senior author Phyllis C. Zee, M.D. “The message is that you should get more bright light between 8 a.m. and noon.” About 20 to 30 minutes of morning light is enough to affect BMI.
“If a person doesn’t get sufficient light at the appropriate time of day, it could de-synchronize your internal body clock, which is known to alter metabolism and can lead to weight gain,” Zee said. The exact mechanism of how light affects body fat requires further research, she noted.