I'm a very picky eater. A lot of it I think has to do with having no sense of smell, which nulls taste buds. Everything tastes dull and bland to me, and I get sick of everything just tasting like salt or sugar. I do go through months of really big cravings of certain foods though, then will over eat whatever I want, and go on to a new food.There's also the extra pain of my mom going out and buying a bunch of food I'd usually like, only to have me decide I don't care for it anymore and let it waste in the fridge. I also eat a ton of fast food, great for calories but crappy for wallet, because it always has strong flavors. Microwaved stuff is almost always too boring for me, so I get sick of eating after a few bites and let my food go to waste. It's pretty annoying always worrying about keeping my weight up, and gets frustrating for my mom when she has to make separate meals for me because I won't eat what she's cooked for everyone else.
When I have food I like though, I have a huge appetite. When I'm in the hospital I gain almost 10 pounds a week from eating huge meals every day. At one point at a hospital I used to go to, they believed I was feeding my visitors because I'd be ordering 2 trays full of food, plus drinks and snacks in between meals.
Don't know how similar this is with other CFers, but these are my unusual eating habits.