It would be interesting to see if the developer went that deep: a character that starts off overweight/fat/obese during character selection becomes slimmer as they move across the land (perhaps down to the steps they take?). I don't anticipate that kind of foresight, but I'm happy to be unexpectedly surprised.
Personally, I’d see that as overly complicated as well as oddly judge-y about fatness, given (as folk have already said) the lack of enforced realism in other areas. Not that it would be a bad thing to be able to change our characters’ body types (along with other features) in the course of the game, but I definitely think that it should be down to the player to choose rather than the game forcing us to change or trying to model changes to BMI, which sounds like a can of worms that shouldn’t be opened. It would make no sense for it to only apply to fat character models, so if it’s not to pick on fat characters then feasibly any character could gain or lose weight. Would it calorie count our evening meals as well as measure activity? If we select more than 40 food units per night, or rest multiple times without having walked far, will our characters put on weight if they start off thin or normal? Might we starve if we rest too many nights without food? Should we see our characters slowly grow or shrink, or does the body shape just jump suddenly to a different model at a certain threshold? Why would only our character’s fatness or thinness change over the course of the adventure, and shouldn’t we also see them, eg, become more muscular if we increase strength?
I just wouldn’t go there, and would simply offer players the option of fatter character models and let us decide whether or not they were realistic for our character concept (if indeed we care about realism in that way). And let any supplementary features be driven by people who actually want to use those character models, rather than those who wouldn’t use them anyway because they think they’re unrealistic.
