It really depended on what lifestyle was considered expensive and heavily varied with geography and food regimes. Although for a long time being well fed was a primary indicator for wealth, until it lost importance.
That said, I don’t think that ancient malnourishing is comparable to modern fitness.
Noble and wealthy, yes. Beautiful, no.
Yes, beautiful. Time to revisit your priors.
Desireable. Not beautiful, or at least not more beautiful than women of average or slim build. It wasn't attractive to be heroin chic or rail-thin like a 90's supermodel, but it also wasn't attractive to be obese or heavily overweight.