There's been a load of talk about this recently, though the research was done a while ago. I've sort of changed my interest in leptin (which has a lot to do with cravings etc) to dopamine
What fascinated me was that the rats and mice in the experiment, who had the low dopamine receptors, were so crazy to get their 'hit', that they would risk an electric shock to get to it.
The rats who hadn't been eating the junk food, avoided the signal indicating they would get a shock.
There's not doubt in my mind that though I can now eat junk food in moderation, for a long time I did have to take loads of care when trying it out after getting to goal.
And even now, I have much control if I eat unprocessed foods most of the time anyway. I always knew that I wasn't greedy, that something else was going on, and now we know there are umpteem hormones and signals that try to interfere with our conscious choices.
But food addiction, like any other kind of addiction can be sorted, and yes, it's not easy, but fortunately we're not doomed. The power of conscious choice remains stronger if you let it.