id eat your regular food. You dont need an energy goo for a 5K. they are PURE (and i mean PURE) sugar. Meant to break down easilyand quickly to be used for energy. They definitely wont make you *not* hungry. and the key is to use them BEFORE you need them, before you deplete your liver/muscles of glycogen...like every 5 miles, to keep from gettingdepleted, which occurs after running(exerciding) for 90 minutes, give or take.
Eat your regularly scheduled food, and eat it a little before the race (an hour? whatever works) so its not just sittiing in your tummy when its go time, but is already being broken down..
good luck!
FYI if you were going to do goos, your just as good to eat a small bowl of honey, or some skittles, or sugar packets from starbux! I like jelly beans and MikeNIkes, personally