I like a wide range of body types, but both fat and thin become a turn off in excess, taking care of yourself is the main thing. Psychologically I want a girl to have self control and self respect, and genetically my DNA wants a healthy mate that can propagate my genes more effectively.
When I dated a chubby girl and really started to fall for her my preferences shifted in that direction. I loved her exaggerated curves not for their own sake but because she had them.
Attraction is fucking complicated.