i was normal, healthy, and underweight all my life up until last year - i'm 5'2" and weighed around 95 lbs (normal weight for my height is 105-130, depending on body type. i weigh 120 now). whenever i'd sign up for health insurance, i would have to go to dr exams to prove that i didn't have anything wrong and that i was at a healthy weight.
naw, as long as it's not grotesquely underweight, there's a little bit of leeway. just like you can be healthy and overweight :)
we've never been allowed to be happy with how we look. You can't sell crap to happy people, I guess.
I think because they used to wear more modest clothes.. and ALWAYS wore foundation garments.. women with a little meat on their bones had all of the fat held and supported in an attractive way that made their figure like an hourglass. Women who were skinny (in this sense i assume they mean flat chest and flat butt, as they weren't too keen on mentioning those body parts in ads back in the day) seemed to have a boyish figure in the clothes of the past. Then the 60's came and people took off their bras and let their stuff flap around everywhere. Nowadays almost all women wear pants and shirts with thinner fabric.. so the littlest bit of jiggle in a normal healthy sized (size 8 ish) girl is hard to hide.

Also, think about this. Many high fashion designers are gay men. Naturally they would be attracted to the image of a thin young man, but it is much more popular to design for women. Therefore they got models with the most lean, boyish figures possible to design for. The whole fashion scene is a fantasy world, and it is really sad to see girls thinking that the 5'11 105lb supermodel is "how you are supposed to look", but it happens.

also, small waist has always been the most important thing in beauty, I think
also, small waist has always been the most important thing in beauty, I think

Yep! People are always saying how standards have changed, and they have, but we tend to forget how corsets were a fashion mainstay for years. If your waist wasn't that size naturally, there was at least a way to make it look like it was. Once women decided they didn't want to wear foundation garments, they took to dieting.

Then in the Victorian era, there were those bustles with a big bow above your ass. I don't know a woman alive who would want to make that area look bigger these days, lol.

What you said about male designers made me think of the time I read about this one guy who said that "curves mess up the line of the clothes." Or something like that. He was defending the ultra skinniness in the industry.
An adult woman...5'11'' and weighing less than 120? I know there are some out there, but Hot Dan! I'm 5'11'', and people start to get concerned when I dip below 150.
The more things change, the more they stay the same. If the women are too skinny, help them gain weight. If they're too fat, help them lose it. Happy women don't buy as many pharmaceuticals, I guess.
Skinny girls are not glamour girls? Then I am DAMNED GLAMOROUS, baby!
I think that blond guy down there could care less about her curves...hes really got the hots for her chin.
The top guy seems to really be digging her hair. At least Middle Guy is staring at her chest.

I guess a 33% success rate is better than nothing.