The "real women have curves" thing is usually a proclamation against all the skinny, fake women we see portrayed in the media.
But, I think that some people forget to realize that a "real woman" may be any shape or size. Skinny, fat, curvy, tall, short, tall and fat, short and skinny, it doesn't matter. A real woman should be defined as a woman who is not afraid to be the current person she is, to embrace her natural self.
Not just another plastic-y, fake, airbrushed bimbo portrayed in the media or movies.