Sexual Fluidity and Body Image: Does one protect the other?

I was talking with two very close friends of mine who were sharing with me the body-image issues they've had since childhood. I finally asked them, "So when did your issues with your body start?" They both said, "I've always thought I was fat." This made me incredibly sad, because I think they are both beautiful women, on the inside and the outside.

One them showed me pictures of her as a teenager, beautiful and healthy, standing next to girls in her high school who were stick-thin. "You see why I always thought I was fat? I was comparing myself to these girls." Didn't it occur to them that maybe these girls had body issues as well and were leading unhealthy lives just to get as thin as they were?  It particularly disturbed me when the other one said, "Even when I was exercising and losing weight, I was never satisfied. I always thought I could lose ten, twenty more pounds." I reminded her that that was the whole point of an eating disorder - someone who, no matter how thin they get, they always look in the mirror and see this ugly, fat monster. Someone who is genuinely mentally and physically ill.

Of course, both as a psychology major studying eating disorders and a feminist, I've long been aware of how the media promotes rail-thin women, to the point where anorexia for models is the sexy thing to do. Case in point:
http://www.youtube.com/watch?v=VS2mfWDryPE

But at the same time, for me personally, I've never understood that mentality, even as a kid. When I saw magazine pictures of beautiful, thin women - not necessarily unhealthy, but slender - I wouldn't compare myself to them, I'd think "Man, she's hot." I appreciated her beauty without coveting it in any way. Why was I immune when I should have been socialized to believe I should look like them? I have a few theories - first of all, unlike a lot of middle-class white mothers, my mother never pushed any body issues on me. She never once commented on my appearance or my weight, (except maybe that I eat like a bird and should eat more, lol.) And when some asshole broke my heart, my father would always be there tell me how beautiful I am and that any man would be lucky to have me. It never really occurred to me that not all parents are like that.

But like I said, when I would see these images of beautiful women, I appreciate them wholly. Instead of comparing myself to them, like it's a competition, I take them for what they are - women who are lucky enough to have the money and time to look like they do, though this will not necessarily make them happy. Maybe it's because I have a genuine love and appreciation for the human body, both male and female. I think it's a wondrous piece of machinery, and that convinces me it could have never occurred by accident. And sometimes I wonder if my sexual fluidity actually worked as a protective factor against that kind of socialization that strives to tell girls they will never be pretty enough, thin enough, etc. I don't know if this is the case for all sexually fluid women, but it would be an interesting study. Why do we teach our women (and increasingly, men as well) that our bodies are our enemies, to be controlled and tamed? I'm not saying we should be downing "Krispy Kremes and milkshakes, spending our days thigh-expanding" (in the wonderful words of Eve Ensler). We should treat our bodies well, by not overindulging it or constraining it unnecessarily. Descartes was full of shit - your mind, body and spirit are not separate - your body's health is integral to your mind's and vice-versa.