Today I heard of a study which, not only haven't I read, I can't even find. So, of course, I presume to discuss the contents, as blog standards are lower than closing-time standards. Supposedly, groups of mice were given the same amounts of food and exercise, but differing amounts of light; those mice receiving the most light ended up weighing most. It leads to an interesting idea.
There's a camp of fitness experts who say one should not eat after 8 PM (or 6, or some other arbitrary time), as calories then get turned into fat. Others say that that's completely idiotic, as weight loss is simply a matter of calories consumed minus calories burned. Now there's a third possibility; it doesn't matter so much when you eat, but if you're keeping lights on when it's dark, you're screwing with how your body metabolizes food. The standard idea was that, if you're sitting in front of a computer or television screen at night, you're not moving and you're probably eating and that's why you're gaining weight; the new idea is that your body is more efficient in the light, so you're getting more calories from the same amount of food.
It's a possibility. Light cues are important - there's circadian rhythms, there's vitamin D production, there's melatonin secretion... light does more than allow one to see. There's also some validity to the idea of differences in efficiency; there was a time when dieters were told that celery and lettuce were "free foods," as they provided fewer calories than it takes to eat them; also, there was once a fad of eating cold foods, as the body has to provide calories to heat them to body temperature (and conversely, there are those who advocate spicy foods, as breaking out in a sweat from hot foods burns a few calories). No one's ever connected the two things, however.
The thought continues: Americans have grown fatter as we've spent more time in artificial light in times that are normally dark. First it was television, then it was computers, but there's also ambient light in cities from street lights and security lights, to having digital alarm clocks facing beds to having devices that have small lights to show that they're plugged in even if not turned completely on. The rest of the world is going the same direction as technology (and comparable wealth) spreads.
It might be one more thing to add to the arsenal of weight loss: turn off the lights at night.
5 days ago