The `Dark Shadows` actress was once told she had to lose weight for a role but found going on an all-soup eating plan made her miserable and she couldn`t do it again.
She said: "Before my first film, the casting director asked me to lose some weight, saying, `On screen you`re going to look much fatter.`
"I started drinking soups and then I was like, `I can`t do it, I can`t go on a diet`. It`s hell, it makes you very depressed - food is so important to me. I couldn`t go on."
Eva admits she feels like an "ugly duckling" in Hollywood, but would not undergo cosmetic surgery to improve how she felt about herself.
She said: "It`s not all about physique and how beautiful you look. In this business actors who have Botox or surgery make you very aware of age. It`s awful. In Los Angeles, I feel like the ugly duckling, like I`m from Venus or something."
The 31-year-old star admits she is constantly on the look out for more "ballsy" roles because so often beautiful women are only cast as the girlfriend.
She added to InStyle magazine: "It`s so boring to play the girlfriend. Most of the women in film are there to be beautiful to the man. It`s quite hard to find a ballsy or complex character. So the roles I`ve taken are those. Lot`s of people put me in the dark category."