Refusing to date fat people.. Shallow?

I am a 22 year old male. I weigh 150 lbs. It should be entirely reasonable that I choose not to date girls who are fat. I'm not fat. I like to climmb trees and jump over things and I eat healthily. Why should I have to subject myself to dating fat girls, who obviously don't know how to take care of their bodies, for fear of social persecution?