By Back in San Andreas I fed CJ round on pizza and then spent a game week at the gym undoing it. GTA 6 brings that system back: Jason and Lucia visibly change with what they eat, how they train and how much they sleep. And judging by the retellings going around, the body you build is going to matter in a fight.
Those retellings describe melee that reads builds. Rumour A skinny NPC can drop from one punch, or skip the fight entirely and run. A big heavy guy may take his chances, hit like a truck and gas out in half a minute. An athletic one is the worst news of the three: hard hits and enough stamina to keep throwing them.
It works in both directions, too. NPCs look at your build: a regular passer-by will likely run from a jacked Jason or Lucia, and if your character is skinny and soft, anyone may fancy their chances. Rumour It fits what Rob Nelson told IGN: start something in GTA 6, and instead of scattering, people may escalate.
What I like here as a tech artist is one system wearing two hats. The same parameters that shape the body in the gym mirror feed the decision an NPC makes: swing or sprint. Rockstar has also said it rebuilt its animation systems for NPCs of different heights and sizes, and that’s exactly what makes “the big guy is gassing out” readable on screen without a single bar over his head.
The weight system and the varied crowd are official; how all of it lands on the combat is still preview retellings. But I already believe the shape of it. In San Andreas the gym changed how you looked. Here it may change who dares to look at you wrong.