This long-held myth claims that any post-dinner indulgences are converted immediately into fat. Experts are now downplaying this rule because calorie consumption, rather than time of day, is once again the key determinant of diet success. The main point is that a pre-bedtime snack or dessert isn't detrimental to your diet, so long as it's not eaten on the heels of a high calorie day. Overall, the main culprit of diet failure is excessive calorie consumption over each 24-hour period [source: MSNBC]. So, if you've had a reasonable day nutritionally, an evening treat won't completely derail your progress. That said, it's wise not to go completely overboard right before you hit the sack because the human body simply doesn't burn as many calories while sleeping as it does when awake. So, before you indulge in an evening snack, consider how many calories you have consumed that day in relation to how much physical activity you've worked into the mix [source: Weight-control Information Network]. When in doubt, opt for a healthy, filling snack to coast your stomach through until morning.