I did rustle up a few interesting examples. Because I am dedicated that way.
The Son of the Hunter
Okay, so this is a folktale about a hero going out with his companions who all have superpowers, fulfilling tasks given by the king, and eventually winning a princess who has dragon brothers. In one version of the story, the princess is called Dartane, the Fair One of the World. The collector notes that Dartane means "a woman of slow movements and plump." She is quite a capable lady, too.
(You can find a version of this story - and sources - in my own book, Tales of Superhuman Powers)
The girl who turned into a man
I will talk more about this folktale type (ATU 514) later in the Challenge, but I wanted to note that there is a Hungarian version where the hero(ine) is - appreciatively and repeatedly - described as "having good meat," meaning that s/he is definitely on the heavy side.
(I don't have a translation for this specific version, but I posted another Hungarian version in English here)
Three Strong Women
A Japanese folktale much loved by storytellers. It is about a sumo wrestler who is trained by three generations of exceptionally strong (and "round") women in the art of wrestling. He eventually falls in love with and marries the youngest one.
(Read a retelling of this story here)
I wrote about the epic of Dietrich in detail last year, but I want to mention it again because it is the only traditional story cycle I know where humans and Dwarves (who are described as extremely beautiful short humans) intermarry without it being deemed unusual.
(You can read about the legend here)
The secret of the fairy lake
In this Hungarian tale a girl attempts to bathe in a magical fairy lake in order to turn beautiful (because she is mocked by the other girls, and she never had a suitor). She almost drowns, but in the last moment she is rescued by a boy who tells her she doesn't need the fairy lake's magic because she is beautiful as it is.
(You can find the Hungarian text here, and if you are interested, I can help you with an English translation)
Also, here is a statue of Aphrodite with glorious rolls, just because.
Can you think of any other tales that I didn't mention? Let me know in the comments!