I've been there. I know how that is, too. I wouldn't consider food that didn't make me feel stuffed, and would frequently eat to that point. I was uninterested in "healthy" materials. I like cheese a lot, which translates to me liking anything with cheese as a highlight.
I had to quit cold turkey. I had good reason to, considering that I got married and effectively removed myself from the environment where I had developed my habits. I dropped 40 pounds in roughly 6 months, and it was a healthy drop.
Now, I'm so accustomed to "healthy" food, that overly processed stuff just tastes terrible. Regular soda is overpoweringly sweet. Foods like frozen pizza, box mac & cheese, and fast food literally tastes abnormal. Once you get off the sugar, salt, and fat diet pushed by Kraft, Nestle, McDonald's/Wendy's/BK, Coca-Cola, Pepsico, etc, it becomes very difficult to get back on that diet. It shifts from satisfying your tummy and giving you that pleasant sleepy contentment to just tasting bad. The textures end up all wrong, and you'll find yourself wishing you'd gone for the "healthy" stuff.
It takes time, true. It isn't impossible, and it's remarkable how much your preference will change once you finally decide upon that change.