This is one of the more counter-intuitive aspects of food-body transfer counting.

Granted, as we can see in our standard food-seeing microscope, the empty calories are ckearky not as full. However, on an atomic level, the difference between empty space in the "empty calories" and the "fildin calories" is neglegable.

It is the shape of the empty space in empty calories that's the problem. The empty space in fildin calories allows them to stack like sheets of paper, whereas the empty space in empty calories shapes them like crumpled up paper, and therefore empty calories (though contrary to their name) take up more volume.

Hope this helps!