Calories in food is a measurement of the amount of energy it will provide to the body. I've heard that eating some foods actually make you USE more calories than you consume. Do any foods actually contain less calories than it takes to chew and digest them?
Of course this isn't a significant amount of calories and I don't expect this to be some miracle weight loss technique. I'm simply interested if the calorie use to actually process food is small enough to let some foods "slip by" calorie wise.