The main activities of the game require energy, you will need it when working, studying at university or training in training camp, ...
As you can see on the image the player have 325 points of energy, the maximum is 500.
Some activities can hurt you, once injured your energy consumption increases.
As you can see on the previous image there is a "Eat" button below your energy bar.
As you can see I have 165 breads in Serbia and each bread give me 26 energy points.
In the right corner you can see my hunger points, actually I have 24/24 hunger points, each time I consume a food I lose a hunger point, so I cannot eat indefinitely.
If you put your mouse on your hunger points you will see that you recover 1 point per 30 minutes.
You can rest in your houses to recover energy too.