Mice robbed of darkness fatten up
Time of day can affect calories' impact
By Janet Raloff
When it comes to weight management, the timing of dining is pivotal, a new study indicates. At least in rodents, food proved especially fattening when consumed at the wrong time of day.
As nocturnal animals, mice normally play and forage at night, often in complete darkness. With even dim chronic illumination of their nighttime environment, however, the animals’ hormonal dinner bells rang at the wrong time. Affected young adults began eating most of their chow during what should have been their rest period. The result: They fattened up and developed diminished blood-sugar control, researchers report October 11 in the Proceedings of the National Academy of Sciences.
The animals didn’t eat more or exercise less. Throughout the eight-week study, their caloric intake — and output through exercise — matched that of lean kin afforded a truly dark night.
“I suspect that what we’re doing is demonstrating that a calorie is not always just a calorie” — at least in terms of weight gain, concludes neuroscientist and team member Randy Nelson of Ohio State University in Columbus.