Plus size clothing for women -- namely, size 14 and up -- is no longer just the domain of budget American clothing. Some of the most prestigious European houses, including Balenciaga and Oscar de la Renta are getting into the business.

It's good business sense. There's a $19 billion a year market in plus size clothes in the U.S.

Kate Betts is a fashion journalist who's been watching fashion in all the sectors explore new lines for plus size consumers and adding larger sizes to their primary designs.

"There's a whole movement in terms of the less expensive end of the market attracting a younger consumer in this market," Betts said. "Brands like Forever 21, Lucky, H&M and the Limited are all doing plus size lines."

Plus sizing isn't the only area where higher-end brands are taking their cues from low-end, fast fashion when it comes to plus sizing.

"The less expensive end of the market has been able to turn over so quickly," Betts said. "So the high end has had to pay more attention in general to what's going on in the low end of the market."

Even Adele may be dipping her toe into fashion. The multiplatinum and Grammy-winning recording artist may develop her own plus-sized line for Burberry.