I imagine this could be VERY technically demanding depending on the character creation systems at play and how the whole system works.
In Skyrim, for example, there's just a weight slider. You might say "I remember more character creation options", and you'd be correct, but the weight slider is the only thing something like this would be concerned with, as it's what affects physique. It would also hardly be worth messing with, as characters would just go to "not that bulky" to "bulky".
Fallout 4 has something that could work better with this. Instead of a slider going from light to heavy, it's a triangle that allows for really thin, muscular, and heavy characters with plenty in the middle area.
Granted, I also think Fallout 4 would spontaneously combust if there was a ray gun or something that messed with that on the fly. I could be wrong about that, but I just imagine crash after crash.
That said, I think a lot of physical effects could be represented by messing with just muscularity, weight, and height, and I've got to figure there are modern games that could handle this sort of nonsense.