One of my favorite parts of GTA SA was how you had so much control over your character. Along with the largest collection of clothing and accessories the franchise has yet given us was the ability to mold CJ's physical condition. If you wanted him to be skinny, that was possible. Likewise, he could be rotund or chiseled. Your choices throughout the game impacted your physical health over time, and occasionally required attention which lent a sense of realism to the gameplay. Did you like this feature of GTA SA? What shape did you keep your CJ in, and would you welcome its return as a feature going forward in the franchise?
I actually like it, like you said it gave the game a nice realistic field with consequences if you are not too careful in the game.
My CJ was always muscular. I don't think there was any advantage in keeping him skinny, except for not having to bother with the gym I guess. I wouldn't mind it if this feature returned, but I know for sure that not all players liked it.
I have never actually given any thought to it. I also fed CJ when necessary and he was neither fat or with muscles. With my next playthrough I might experiment more because at first I was after the story.