Body image isn’t always about the number of your weight or the number on the tag of your pants. Sometimes it’s about your surroundings and your peer group and their attitudes.
Case in point, me. I am very much not prone to weight fluctuations. I’ve been the same size (for reference, ~150 lbs, 5’7", size 10-12 depending on the maker) ever since I was about 14. I’m now almost 20.
When I was 14, I lived in a town whose high school had one of the highest rates of eating disorders in the nation. My friends used to joke about “the town name diet,” which consisted of a plain bagel with no topping and a can of Diet Coke. My little sister had a classmate who was normal-sized in every way, but went on a diet by fifth grade. The girl would pinch the babyfat on her upper arms and moan about how she needed to lose weight.
I could go on and on, but I think this example really captures the essence of that high school: The perenially most popular brand of jeans was a tight black pair of stretchy jeans that had the number of the waistband size stamped on the back of the waistband in inch-high white letters. To some extent, a girl’s physical beauty was determined by how small the waistband size was. If you could get it below 25, you were smoking hot. (Insert corset reference here.) I have clear memories of uncomfortable babyfat poking out of the waistband and developing reddened stripes.
Not surprisingly, I thought I was the fattest, ugliest girl ever. But from an outsider’s position, I saw “beauty” tied up so tightly with unhealthiness and obsessions that I ended up rejecting it in any form. I gave up on looking attractive entirely and turned into a greasy-haired suburban goth. Hey, worked for me.
Several years later, I moved. I ended up living in a building full of girls who had all sorts of “fuck your sexist beauty standards” paraphernalia and stuff taped to their doors. The other kids at the first college I went to had a very relaxed idea of what was attractive. Nobody was on a diet, nobody exercised twice a day,  and nobody was actively unhappy with the way they looked.
Now I think of myself as being skinny. Remember, physically nothing about me has changed. And once it crossed my mind that I wasn’t a land whale after all, I started developing an interest in stuff I’d previously looked down my nose at - like skirts and heels, makeup, perfume, shaving and the like.
(Don’t get me wrong - that stuff can all be misused as a way to conform. Although I think this (paraphrased) motto, as seen printed on a department store makeup counter, is a good attitude to have: “We sell cosmetics to enhance individual beauty - not to conceal.”)
I’m not even going to pretend I know how the culture of that high school got started. And contrary to what some people think, making the effort to lose 15 pounds or wearing form-fitting clothes will not lead to self-esteem - it’s entirely possible to look beautiful but not feel beautiful. The dozens of beautiful but miserable girls from my hometown prove that point.
I will say, though, from what I saw, one of the things that continues the cycle is teenage girls’ magazines - even though they’ve supposedly improved in recent years, they present articles to 13- and 14-year-olds about other girls their age going on dates, going on diets, making the head of the cheerleading team, and doing a lot of cool-seeming “adult” things like shaving their legs and wearing full makeup (which is why I initially started doing those last two things - in fifth grade, might I add - because from what I saw, other girls my age were already into it, and it was just something teenage girls did.) Holy run-on sentence, Batman. This kind of stuff starts young, and in some cases it lasts for the rest of your life.
I’m a bit of a cynic when it comes to body image - I don’t necessarily think parading the kids into a gym and having someone stand at a podium and tell them how important it is to love their bodies will do anything. I think if we’re going to be committed to building healthier self-images among women, and especially teenage girls, we’re going to need to start unleashing some media images and impressions of our own. How about somebody start up a magazine - not just a photocopied 'zine that gets passed out on corners, but a real glossy - aimed towards teenage girls that promotes a much less narrow idea of beauty and maturity? (And not something touchy-feely saccharine or co-written by a panel of 40-year-old men either, but something cool that teenage girls will actually read?)
5 years ago I’d have ended that paragraph with “Oh, but it wouldn’t sell. The advertisers have got to find a way to bully teens into buying their crap.” I hope someone proves me wrong on this.