Eat Late—Gain Weight

Isn't it just calories consumed and energy expended that count when it comes to weight? Nope. As it turns out, people with a penchant for middle-of-the-night snacking may pay for that habit with added pounds, even if they consume the same number of calories overall as people who don't eat during the night, a recent study suggests.

For six weeks, researchers fed two groups of mice an identical high-fat diet. One group was fed during times of day when mice normally are sleeping...the other group was fed during their usual active time. Overall calorie consumption and physical activity levels were equal in both groups.

Results: Compared with mice that ate during their usual waking hours, those that ate when they ought to have been asleep gained 2.4 times more weight, on average and wound up with 8% more body fat.

Theory: The body's internal clock regulates energy use, programming itself to more effectively burn calories consumed during active times.

Lesson: Even when you stay up very late or wake up hungry at 2 am, resist the urge to make a middle-of-the-night foray to the fridge.