I'm not familiar with them specifically, but laboratory studies on body image often involve showing women. They evaluate women's attitudes about their bodies and then show them images and then evaluate them again afterwards. It has been reinforced that women who view so-called average-size women or plus-size models in advertisements feel less bad about their body at the end of those experiments, so I think it does have an impact.
Italy, Israel, and India have all looked at banning models who are underweight. I don't know if that would have an incredible impact because we're getting a lot of our media from the United States, but I think encouraging health and working to break down the idea that beauty is one size would be helpful.