"That's where it's unfair: the judgement that is put on women for how we look," Munn said.
"If you're looking bad, you have to cover up. If you're looking good, you've done something or made a deal with the devil," she added.
The "X-Men" star, 35, also talked about the role her mother had in developing her independent personality.
"My mother never coddled me. She never really helped me. What I did learn from her was how to have a strong sense of self. She gave me the tools to figure out how to solve problems and fight my own battles.