For too many American girls, being "model thin" is a very real aspiration, and it starts at a shockingly young age. In one recent study, researchers found that TV programs focused on appearance are swaying the self-esteem of girls as young as 5 years old.

It's no wonder. Bombarded with countless media images of thin female models and actresses who look beautiful by modern American standards and appear happy, many girls—including the youngest and most impressionable—view them as role models. It doesn't help that real-life role models, mothers in particular, too often openly obsess about their own weight; that male role models, like dads and older brothers, make clear their preference for thinner women; and that an overwhelming percentage of girls' clothing features body-hugging, midriff-baring styles most comfortably worn by the ultra-thin.

WebMD talked to experts to find out which factors influence girls' ideas about body image and what parents can do to help their daughters develop a healthy attitude about their own bodies. Here's what they learned…