I'm ALWAYS hungry, too. I thought that you weren't supposed to feel like that even when dieting, if your diet is good. I eat often, high protein, and all that. It's good to hear that it's normal to be hungry.
Eating a lot of sugar will obviously send your blood sugar way up, only to have it come crashing down later on. After it crashes your body will start to experience hunger pains in order to get you eat something that it can break down to get those levels back up. I eat very little sugar and i NEVER have hunger hit me out of no where. If i start to feel hunger, i know i have about an hour to a hour and a half or so before i start to get really REALLY hungry.
By sugar i mean artificial sweetners because some of them effect insulin
If your carb intake is low, you gotta watch that stuff. I almost passed out after drinking about a liter of Crystal Light one day when i was helping my sister move into her new place.