I have a friend who did a small amount of modelling years ago. "Curve model" originally meant women who were slightly larger than conventional models. If a conventional model was a size 0-4, a curve model would be around a 6-8. They were often women who were thin, but were either 1.) too muscular or 2.) has too large a frame for conventional modeling, but who were still attractive, fit women who could sell clothes. They were often classified as "athletic" models. They were also very commercial because the average person liked a model who wasn't part of heroin chic at the time and they looked healthier and more "realistic." But now, since the public is fatter, the models have to be fatter to be "realistic." A size 8 is now "scary skinny" and a size 18 is average and a size 28 is empowering.