Echoing what Globaliser said, if you can arrive early enough to eat before the flight then I'd recommend going through security in Terminal F, where your flight leaves from, then take the underground concourse to Terminal E (a 5 minute walk or a quick train ride) and eating at One Flew South. It's far superior to both anything you would have on board and nearly any other in-airport restaurant.

http://www.oneflewsouthatl.com/foodanddrink.html