I mean, an overweight adventurer doesn’t make much sense, as the process of daily walking long distances, regularly fighting, and living off travel rations would naturally slim anybody down quite a bit, but the list of things that don’t really make sense when you think about them in Dungeons and Dragons is pretty long so who cares?
That said, the chances that they are adding in heavier body types is pretty low. Those who want to play characters with a power lifter build will just need to do what they’ve always done: play dwarves.