In the past year or so, there have been efforts to ban models deemed "too thin" from participating in high-fashion runway shows. If a model arrived with a BMI in the "underweight" range, she would be pulled from the lineup. The goal of all this is to combat eating disorders. This isn't effective for several reasons:
1. BMI isn't a good criterion for "health." It's especially difficult to apply to adolescents, and female models especially are getting younger and younger.
2. Being super-thin will have even greater cachet when it becomes forbidden. A model could spin being "too thin for Madrid" or "too thin for Prada" into an asset. Designers who know that controversy sells wouldn't balk at using super-thin models.
3. More media attention = more photos of shockingly thin models, regardless of if they're still on the runway or not.
4. It's sexist. Male models aren't as drastically thin as some female models, but they're getting there. Men get eating disorders, too*.
5. You're missing the target audience. I remember looking admiringly at thin runway models, sure, but I was just as envious of actresses, singers, and magazine models. If you're trying to influence girls in the 12-18 age range, targeting haute couture isn't the most efficient tactic - they're more in tune with popular culture.
6. It doesn't get to underlying issues. As a society, we attach normative values certain foods, lifestyles, and body types. High-fat, high-sugar, high-carb foods are "bad." Low-calorie foods are "good." Toned, exercised bodies are "good," flabby thighs are "bad." It's still socially acceptable to denigrate overweight and obese people, because it's assumed that they're too lazy, stupid, or stubborn to lose weight and live "healthfully." My own experience with anorexia was much more about fearing being fat - thus being a "bad" person** - than wanting to look like a model.
Banning models is a drop in the bucket. Besides, do you really want to take away these girls' meal tickets?
* Just don't call it "manorexia." Or "drunkorexia" or "brideorexia" or "momorexia." But that's for another post.
**Apologies for the quotation mark overload.