Hi, I am a 24 year old male who is of a fairly skinny build, more or less healthy all round. I have a pretty peculiar problem which is driving me nuts. I'm always hungry. I mean, seriously hungry.

I eat three to five meals a day. My diet is mostly carbohydrates and protein. It's not the healthiest diet in the world. But I'm always starving. I'll eat two breakfasts, lunch, a takeaway, a dinner and an 'after dinner' which is worth another takeaway, and I'll wake up so damn hungry I'll be vomiting bile, and the process starts all over again, cramming as much food into me as I can before my work break ends or I'm too exhausted to keep eating. What's stranger is that I don't gain weight; I'm of normal, if slightly underweight proportions to the rest of my body.

My stomach will pang with hunger, I get dizzy and get hunger headaches, my vision will become blurred, and when I get home from work I don't exactly sleep - its more like passing out from hunger and weakness. But I eat so much that it just seems impossible, like the growling in my stomach is indigestion or normal routine, but then I'll vomit bile.

I've been diagnosed with various disorders, and prescribed various medications that don't work. I've even treated myself for parasites. Why am I so hungry and tired all the time?