After the first hour I aim for 200calories/hour. (I weigh 125lbs). If you weight much more than me (most men), aim for 300cal/hour. This will stave of bonking and the miserable drained feeling many have post ride. (You know, the one where you lie in bed exhausted with your heart pounding and can't seem to sleep.) For fluids, it depends on temp, but be sure to get something with sufficient electrolytes. I've started adding drops of "elete water" (http://eletewater.com/) to whatever drink tastes good.