I used to be that way about dairy products and quorn. I also had a thing about melon and actually had at least one melon salad (sometimes much more!) per day for about 5 years! I then had an operation where I was not allowed to eat anything and reaslised that the sky did not fall in, I managed it! I was so pleased with this that I decided to cut the above out and see how long I lasted. I had felt such a compulsion to eat those things that it began to feel like an addiction, I didn't enjoy eating what I did as much as I felt compelled to eat them, even when I was not hungry!
I now eat apples, chicken, fish, whole jumbo oats, green vegetables and drink black tea.
But the one thing I have problems with stopping, is diet lemonade. I have been addicted now for the past 20 years! At one point (ok I was very ill with anorexia) I would get through about somewhere between 3-5 Liters of Pepsi Max per day, every day for about 18 months!