What could cause chronic severe ravenous hunger?

I suffer from chronic ravenous hunger feeling. I never feel satiety either. I have seen many different specialists including an endocrinologist who ran all the blood tests and basically told me it wasn't a thyroid problem and I didn't have diabetes. She treated me with a shot called "Byetta" that diabetics use hoping to help my hunger, it works by slowing down the digestion of food, this did not help and I had a lot of fatigue after using it, but "fatigue" is not even a side effect. Other symptoms include disruption of sleep and when I eat anything with carbs, say just a single banana, or a yogurt, or a sandwich, I become very sleepy and fatigue and unable to function properly. When I was in college I couldn't eat all day because it would make me too tired, it's weird but I have more energy when I don't eat. For years I woke up in the middle of the night starving and could not sleep until I ate something, which caused a lot of weight gain. I lost this weight sticking to a very healthy strict diet, but I couldn't sleep. I have seen a nutritionist and eaten like a normal person and I just lose mive amounts of weight when I eat normal portions. I've always thought it was connected to my sleep but the sleep specialist here had never heard of this. I can eat a huge meal, fall asleep for 30 minutes, an hour, or 4 hours, and I always wake up ravenous, worse than if I had stayed awake. I understand this could be psychosomatic as I do suffer from anxiety and depression but my psychologist and psychiatrist, both each with 30 years experience individually, have never heard of this symptom and aren't sure how to treat it. It is not medicinal either. I was referred to Shands psychiatric center, because of depression and insomnia, they had never heard of this either. Last thing, it becomes 2, 3, 4 times as bad when I'm stressed and having anxiety, but the problem started before I ever had any anxiety. COULD THERE BE A PHYSIOLOGICAL CAUSE? Also, suffer from central pain syndrome, chronic fatigue syndrome, and interstitial cystitis.