I've also heard this said. However, when I went to the Metropolitan Museum of Art, and looked at the paintings and sculptures of women, I wouldn't quite call any of them large (they all seemed to be at a healthy weight; no one I saw seemed to be what people might call fat, although they might not be stick-thin / have a bit of stomach), except for maybe some of the French paintings of royalty (and then, you wonder if they were painted because they were royalty). I would be inclined to think people would have painted what they thought were beautiful?

So, historians: would you say that the depiction of women in artwork were good examples of what was considered attractive? / How "large" are we talking when we say large?

Careful, because what have been considered large and what was considered skinny have changed as nutrition have changed. Ruben is famous for painting voluptuous models, to the degree that "Rubenesque" have become an euphemism for overweight. But when you actually look at the paintings, the bodies depicted are probably average compared to the US average today. Indeed, if you look at depictions of idealized female beauty through history, they would generally not be considered large today - but neither are they decidedly skinny or bony.

Skinny or bony features as ideal of beauty is pretty new. I believe It first appears in the 1920's where a slim "boyish" look became fashionable and corsets (which accentuated the curves) fell out of fashion. The fashion industry have generally favored relatively slim models because they accentuates the clothes better. This have given rise to an ideal of beauty which is much skinnier than historical ideals. But be aware that fashion models are not the sole ideal of beauty - movie stars, for example, have generally more varied body shapes. Marilyn Monroe for example was definitely not large, but still more curvy than say Twiggy.