Just like everything else I do I jumped in with both feet. My eating habits WERE atrocious. I ate chocolate by the pound at least twice a week,fast food just as often if not more, and a meal without potatoes...no way. I drank liter after liter of pop.
For me, going cold turkey and getting everything out of my system at once was best.
I also quit smoking many years ago the same way.
Just stop and never go back.