"Grand Theft Auto VI" is not only returning to Vice City but also bringing back a character development system familiar to veteran players. During a recent non-playable demo at Rockstar's Edinburgh studio, foreign media discovered that the game will track individual stats for Jason and Lucia, including height, weight, sleep, nutrition, calories, physique, muscle, fat, and strength. This design is reminiscent of the system in "Grand Theft Auto: San Andreas" that allowed players to change CJ's body type.
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Rob Nelson, Co-Studio Head at Rockstar North, confirmed that the food players consume will directly impact character stats. He stated that eating would have a significant effect on health, providing substantial buffs that would be very useful in certain situations.
Conversely, if Jason or Lucia eat too much, their weight will visibly increase. Players can then improve their physique through exercise.

Nelson further explained that gyms are available in the game where players can work out to increase muscle mass or strength levels. He added that players can take Jason and Lucia to the gym together or individually, but if they go as a pair, both characters will train simultaneously, allowing for dual stat management.
The demo also showed "aerobic exercise" prompts appearing when characters run, and food items were marked with heart and lightning bolt icons, similar to "Red Dead Redemption 2"'s health and stamina system.
This suggests that "Grand Theft Auto VI" could further integrate the body customization of "Grand Theft Auto: San Andreas" with the more detailed life simulation of "Red Dead Redemption 2", allowing players' diet, exercise, and even sleep to genuinely shape the physical states of both protagonists.
via: IGN