When the chocolate splits and the largest piece moves right it gets bigger (the angled part grows about 1/3"). While it grows, it grows big enough to make up for an entire piece of chocolate (which is the extra piece that is eaten each time). With all of the pieces moving together it makes an optical illusion that everything is staying the same size.
as the three wide section slides to the right the bottom gets just a tiny bit longer...... over the length of the diagonal the growth adds the full extra chunk....... watch the vertical edge of one of the bottom partial chunks.... you can see it get longer.
No, this really works. I went to the vending machine and got a Hershey bar...I've been eating non stop for like an hour. Holy cow....this is great....my stomach is starting to hurt, but so worth it!