When jowls start to form, the lower part of the frontal view of the face starts to develop a "square" look.  Imagine a line that starts at the bottom of her left ear, and runs to the left jowl, across to the right jowl, and then up to the bottom of the right ear.  Kind of a square.  In the after picture, our eye follows from the bottom of one ear, to the center of the chin, and back to the bottom of the other ear.  More of a triangle.