Which Weighs More, 100 Calories of Turkey or 100 Calories of Gravy?

Sounds like the old trick question about which weighs more, 10 pounds of rocks or 10 pounds of feathers—I mean after all, if a pound is a pound, shouldn’t a calorie be a calorie? Not quite says a Prevention magazine article that points out that cutting back on a meal to save more calories for dessert just doesn’t add up the way you would like it to.