How long can you survive if you do not eat?

as we know that, eating is to add energy so we get a strong setamina to run daily activities, then what if we do not eat how many days? Can we survive? not eating and drinking for a few hours, like we do in the month of fasting, of course we can still run the activity because at the time of magrib we will eat, but after a few days we do not eat? Can we run daily activities?