Honestly, the only thing that's worked for me is learning to cook well. Grain and sugar-based foods are hard to turn away from largely because of their convenience and tastiness, so you need to outcompete that. If your new "diet" isn't equally or more delicious and satisfying than the one that's killing you, of course it's bound to fail.
I highly recommend checking out Matt Stone's 180 degree kitchen blog. While he does use legumes and grains, you can learn some good techniques.
“The whole concept of a macronutrient, like that of a calorie, is determining our language game in such a way that the conversation is not making sense." - Dr. Kurt Harris