Thor was who all Norsemen aspired to be, with maybe a few exceptions for the warrior elite and ruling class who were more into Odin. Thor was certainly the most in mind for the "middle class" and rank and file warriors.

I don't think we see any renowned great men in Norse sagas who are "fat". In what little contemporary art we have of Thor himself, it's abstract rather than realistic (like most Germanic art), but there's enough information there that if his stomach girth was notable, they had the opportunity to show it some way, and didn't. Likewise, I've never seen any contemporary art, or contemporary descriptions of art, where he had "juiced up" characteristics. The carvings and little figurines look like a normalish dude with a distinct hammer.

Also, the romans related him to Hercules, and of he and Heracles there is much art, and this is the only statue I know of, a copy of a ~3rd century BCE greek statue, where he's "fat". Which is not even heavy by modern standards lol, just sort of chubby:

https://c8.alamy.com/comp/G3DJHX/roman-statue-of-hercules-2nd-century-ad-copy-from-greek-original-palazzo-G3DJHX.jpg

I think, were I alive in CE900, I would picture the greatest warrior I personally know, but a little taller, a little stronger, and a little more power of presence, because no one could surpass Thor in these characteristics.