Hi dichotomy, yes that stuff about the forbidden fruit is difficult. It's the 'don't think about a pink elephant' thing that immediately draws your mind to it.
I do think that after about 3 weeks (the rough time that it takes to start changing any habit) that the obsession diminishes a lot - still happens, but not so often and not with such intensity.
Also, I think that is why on here we post so much about alternative things - alternative drinks, and alternative activities. Just tryong to cut something out is devilishly hard, whereas replacing it with something else is a ittle easier. But you've really got to work at finding something that you really like. And make sure you have it in the house. If we stick with your dieting comparison, then if you're craving a sticky cream bun, you're not going to be happy with the last (slightly soft) crispbread from the packet topped with a smear of low fat spead. But you might be more satisfied with a bowl of fresh raspberries and strawberries and a scoop of low fat frozen yogurt ice cream.
I have to work hard at it though, I have fresh limes in the house, I have to keep topping up the ice cube tray, I buy tonic / soda in little cans and keep them in the fridge, rather than having the flat warm dregs from an old bottle of tonic.