It's the design of the outfit too. The figure-like black lines are meant to deceive your brain into believing that a slimmer body is under bulky clothing, despite the fact that the dress tightly wraps her fat.  Yes, good point.  Also, they probably touched up her skin to make it look smoother and less saggy.    It's funny because when these "plus size models" are featured, they try to minimize the fact that they are fat.