If you are one of the 120,000 people (give or take a few) attending Comic Con, you're going to eventually get hungry and I HOPE you're not just going to grab a hot dog or something equally full of chemicals/devoid of nutrients!
Eating well while traveling is always a bit of a trick, but the best place to find food is at a grocery store. Not only will you save money, but you can actually find real food that will keep your energy up (something you need for sure at Comic Con!). Some good suggestions are trail mix (not granola, which is full of sugar), rice cakes with hummus or small pieces of good quality cheese, and fresh fruit (of course!). If you're lucky enough to find a supermarket with a salad bar, you've hit the jackpot. Just stay away from the salad dressing--most pre-made dressings are just more chemicals, fat, salt, and sugar. A little olive oil and some vinegar are not only tasty, but actually beneficial to your health. Vinegar boosts your fat-burning metabolism and also increases the good bacteria in your system (this does great things for your immune system!) and olive oil contributes to the healthy fats you need to break down nutrients.
Be sure to drink lots of water while you're traveling. I know it makes for more trips to the bathroom, but that's really healthier than temporarily shutting down your filtration/hydration system. Besides, every trip to the bathroom is more exercise! Yay for exercise!
Have fun, you lucky Comic Conners! Sorry we're not there--we miss you all!