I've noticed the hunger/thirst bar at the top. I see potential for this system to actually have a good use to the game. It's simple;

Hunger: Causes stamina to drain faster then normal when running/jumping while hungry

Thirst: Affects the rate in which stamina returns back to 100%/ the more thirsty you are the slower your stamina returns back to 100%

Fast Food places already in-game can be used so people can order food/drinks so they can replenish their hunger/thirst. This can also be a good opportunity to add jobs that help xp boost as a citizen. So everytime you complete a customers order, you gain xp as a civillian.