I think people are focusing on "obese" too much here.
There are a huge variety of body types that are able to adventure lol. You know, short people, tall people, someone who's 280 pounds of muscle, someone who's 130 pounds, etc. Also, it's silly that people are really trying to pull "could a fat person adventure though?" line. Really? So a 140 pound person that grew up in a palace and never exercised a day in their life would be capable of adventuring because they're technically not fat? It's a silly excuse to justify NOT changing something imo.
That said, it's not going to happen. Larian isn't going to add something like that this far into development. Hell, i assume they're getting fairly close to going gold.