I have to add here, scientifically speaking, a single sample doesn't make an average. If your interensted in the weight of a glass of water, weigh yourself with the empty glass, then, while still on the scale, fill the water. The weight should change only based on the weight of the water.
i understand where your going, which is "if I eat one pound of donuts, why do I gain 5 pounds?" kind of thing, but remember, calories are a reference to the available energy of a given food stuff, not necessarily the pound weight.
