I'd also point out that a flaw of a system where a character built to appear overwheight would get thinner and more fit or scrawny characters getting bigger and more fit would be that it would lead to all characters ending up with the same build.
Physicality of our characters changing with play style could only work, if the game revolves around making live style choices - in that case our characters look would act as feedback to our choices. Jamming physical changes to game like BG3 wouldn’t work, as it is not game designed around making those choices - we pick our race and class, whenever we save, ignore or slaughter tieflings, but not really what our characters diet is, and how they spend their days, or how much their exercise.
