I like girls with curves and a good figure and a nice shape.
I don't like super model thin.
I get horny by looking at paintings in museums from the 15th, 16th, 17th century of curvy women resting on a nice day couch.
Skinny girls can be hot. Bigger girls can be hot.
I think the whole thing with guys being attracted to very skinny, quite short, nearly pre-pubescent thing is weird. I'd chalk it up to being insecure with themselves, and also their penis size. If the girl you dig is this size/type cool. BUT, if you only like girls who are 5' and 90lbs. that is kind of weird.
As far as BMI, just like a lot of other things, it's an indicator, not a strict scale.
However, I will say many, many Americans these days are just plain fat. It's annoying when anyone tries to chalk this up to being "big boned." Okay, fine, you'll never be rail thin, but you've still got a fat gut and could lose 20 pounds just by not eating such a big dinner. People use this as a cop out.
Fat is fat. And most people are fat for reasons within their control. Just like I believe most drunks are drunks for reasons within their control. I'm no expert, but I've taken plenty of college courses in health and psychology. I've also spent most of my life as an athlete. If you eat less and exercise you WILL get skinnier. Bad genes is overused as an excuse these days.
Last week I was in the car and an entire show was dedicated to plus size woman and if "fat is the norm" today. Sure as hell is, but stop trying to make yourself feel better and eat right.
I will say however that obesity is linked HEAVILY to socioeconomic status, education level, income, knowledge, etc. But then again, rich & poor are really fat in America today. So go figure...