Is it normal to loathe overweight people and be offended by them?

I don't find large women physically appealing, however some people can't help that they are fat. Some have a medical condition that makes them unable to lose it. I have a friend like that. She eats healthy and goes to the gym everyday. She's stronger then most of the men there. Newcomers to the gym will see her, laugh at her, and assume she's a fat, out of shape weakling. Once they see how fast she can run on a treadmill or how much weight she can bench press, they wind up feeling stupid.