Heroines are definitely sexualized in comic books and media, they are constantly showing a lot of skin and most have rather large breasts. A fine example of this, is power girl.
Although this may be viewed as sexist towards women, technically, it is not. Male heroes get it just as bad, in films, the hero is more often then not, gonna be shirtless or have a lack of clothes at one point in the film. There are a lot of examples:
Hugh Jackman/Wolverine. Film- X-Men days of future past.
Dave Bautista/Drax the destroyer. Film-Guardians of the galaxy
Henry Cavill/Superman. Film- Man Of Steel.
This list could go on forever although I don't want to keep on searching images of shirtless or nude men. My point is that both genders are too sexualized in media or comic books. Men are shown as being giant, walking lumps of muscle and women are shown as being giant breasted, sex icons.
For teens this is unhealthy, it's giving a bad example of what there bodies should look like. Females are lead to believe that they should be super-skinny and pretty and males are lead to believe that they should be Super-muscular and handsome.
I know that the title of this post is misleading although it was just to help grab your attention and I couldn't think of a fitting title.