Prolonged exposure to light may cause weight gain

Science : Increased exposure to artificial light, such as from lamps and computer screens, can lead to obesity in humans and other mammals, according to a study published in the Proceedings of the National Academy of Sciences. Mammals have two types of fat: white and brown. Both store energy, but brown fat has been of particular interest in weight-loss studies because it uses that stored energy to convert fatty acids and glucose into heat. Therefore, increasing brown fat activity could stimulate weight loss. However, the study’s researchers found that brown fat activity was reduced in mice exposed to excessive levels of artificial light, which appeared to affect the amount of nutrients the fat could absorb and the activity of a key protein. The result was significant weight gain despite the fact that both the test animals and the controls ate about the same amount and engaged in similar physical activity. Although the current study has yet to be applied to humans, the researchers say that people trying to lose weight may want to monitor light exposure as well as food intake.