A study in the journal Obesity added to the confusion by suggesting that there may be more to nighttime eating than just overeating calories. Northwestern University researchers found that eating at night led to twice as much weight gain -- even when total calories consumed were the same. But this research was done on mice, not humans, and the reason for the weight gain is unknown. And a single mouse study should not cause us to toss out the wealth of evidence supporting the calorie in/calorie out theory.

Still, there are good reasons to be cautious about eating at night. Diet books, dietitians, and even Oprah recommend not eating after dinner (other than a small, calorie controlled snack) because it’s just so easy to overdo it.

People eat at night for a variety of reasons that often have little to do with hunger, from satisfying cravings to coping with boredom or stress. And after-dinner snacks tend not to be controlled. They often consist of large portions of high-calorie foods (like chips, cookies, candy), eaten while sitting in front of the television or computer. In this situation, it’s all too easy to consume the entire bag, carton, or container before you realize it. Besides those unnecessary extra calories, eating too close to bedtime can cause indigestion and sleeping problems.

There’s nothing wrong with eating a light, healthy snack after dinner as long as you plan for it as part of your daily calories. To keep from overeating, pay attention to your food while eating, avoid eating in front of the TV, and choose a portion-controlled snack.