My wife has dealt with this problem. I did some research and here's what I found. Carbohydrates (and pretty much anything else addictive) are "crave-inducing" because of a physiological reaction they cause. It triggers chemicals in your body and brain, not at all unlike cigarettes or other drugs. For refined carbs, it's insulin in the blood, which is followed by serotonin in the brain. The serotonin creates a relaxin…
I've been curious about this for a while: how would one cut out carbs? They're the most easily absorbable form of energy available. Without carbs you would have to bring in energy in the form of fats which can't be good in the long run.
Refined carbohydrates cause an unhealthy "spike" in blood insulin levels. It's the insulin drop that is felt as a "craving." The body "craves" an insulin spike.
And fats aren't bad for you. You need them to live. In general, your diet should be around 40/30/30 Carb/Fat/Protein.
There are tons of articles out there on how to eat properly but I've been paying a lot of attention to Robb Wolf lately. He has been getting some pretty impressive results with his recommendations.