Peasants in late Tsarist Russia preferred stocky, muscular women, to the point that thin women padded themselves out with extra clothing to look more attractive. I don't think the link between "looks like she can work hard" and "hot" was explicit, any more than "looks like she has the economic power to do what's necessary to stay thin" and "hot" are explicitly linked in ours, but the association was there.

Mind you, the anthropologist who documented this was the educated, "Europeanized" daughter of a landlord, one (very large) social step above the peasantry, and her own idea of beauty was the slender, refined maiden of the Victorian/Edwardian age. The peasants' idea of beauty horrified her. I think a group's ideal is based on what's economically feasible in their social universe. If it's possible and economically rewarding for you to reach for the life of someone who sits indoors and never does hard work, then that look is going to be what's hot. If you're incapable of reaching above your social level, but hard work will improve your economic status, then looking like a hard worker will be hot.

tl;dr Follow the money.