Seconding everything Det said. Make several small, permanent changes, and stick with them until they become habit. Simply changing out the food your crave for something healthier is usually enough, and after a while, you develop enough of a taste for whatever your alternative is that you can think about craving THOSE instead of delicious deep-fried sticks of butter.
You want nachos, you think about how good something you cook at home can be. BAM. Craving changed.
Kazz says you don't know what it's like to be a glutton.
Yeah, it's a habit thing. If you'd ever been a fat fuck you would know that you pretty much work your way up to needing a fourth meal every day - usually on account of eating 'cause your bored and/or discovering Cheez-Its - and trained your body to demand more. You're annoyingly hungry all the time if you don't snack, at least until your body readjusts after a couple weeks.
Exercise takes a long damn time to stop sucking and start really feeling good; for me, it was three months before I no longer loathed running. I recommend doing weights if you're up for it, if for no other reason than that they tend to visibly show results faster and actively make you
want to keep going.
I started getting back to three days a week at the campus gym around December, running 20 (now 30) minutes, crunches, and weights, and I genuinely feel a hell of a lot better. It feels dang pretty worth it right now.
Switch to water. Force yourself to like it. Trust me, it's more than worth it.
Yes yes yes
I've been drinking not much else but cold water for a while now, and it kills thirst like a motherfucker. Get a water bottle (I use an empty Vitamin Water 20oz'r), keep it overnight in the fridge, drink when thirsty.