Exactly, society says women should be tall and men should be taller. (See the BBC news article about a future where there are two classes of humans - tall fit ones and little fat ones.)
I think the female media perpetuates the "willowy" myth, thereby making women think they need to be a size zero. On the other men ...well, men like lots of different body shapes, but often prefer a curvier physique and gravitate those aspects of the female form for which a greater fat content is required.
Meanwhile, in the land of foot in mouth disease:
Lordy me. What is wrong with these people?