A few things that have been helping me:
-Snack, but on good things. Fruit, cottage cheese, yogurt, etc. Read the nutrition label on everything.
-Drink water. A lot of water. I've been drinking 4L a day - that helps both reduce food cravings and avoid kidney stones. Fuck kidney stones, seriously.
-Take up a sport. There's no more fun way to exercise than something fast-paced and competitive. If you play video games, stop doing that and use that time to do something out in the real world.