It all comes down to a person's self esteem and self identity. They obviously have a disorder, whether it's bulimia or anorexia its controlling how they want to be perceived in society. Media plays a huge role, but it's actually generalized others that controls the way we think and how we are influenced in our daily lives. Primary groups such as the family and religion may have influences as well, but it has been proven that young adults are more influenced by their friends and peers.
Ah god idk, I'm glad you posted this... I ****ing hate girls that think being way skinny is sexy, well its NOT. It's like really woman, EAT something... I cannot emphasize this enough: