Hi
Refined grains will cause your blood Sugar to rise very quickly, giving you the same kind of high you would get off Sugar - the carbs in these grains get digested and broken down into sugars really quickly in the body so the result is pretty much the same. This happens me too, if I have grains I cant stop craving them, and having sweet cravings.
Eat wholegrain versions of grain products, the fibre in these slows down the rate of digestion and you wont get the steep rise in blood sugar. Have grain products with fat or oil of some kind, this also slows down the rate of digestion.
But basically, if your body has fast burning carbs like this it will crave more, whether it gets them from grains or sugar.
Hope this helped!