I am no expert. But it is good for me to see that other people have the same problems as me..... here are my thoughts.
RE: fast metabolism. I believe this to be one of the factors. A book that has really helped me understand what is happening in my body is Conscious Eating. It may help you. They talk about the different types of bodies and how these bodies digest food differently, and what food is best to nourish these types. I am what is called a fast oxidizer, so food digests very quickly. I do best on a high carbohydrate diet, but simple carbs, not grains and pasta. These types of things I don't digest well, and they make me tired. Fats, I need to feel full; but I have to watch, because I believe too much fats really contributes to my candida situation, and too much will make me tired too.
Parasites: Well, I am always hungry too. I believe one of the reasons is as explained above. BUT...... I was more hungry before I started my parasites
cleanse. And I am SIGNIFICANTLY LESS HUNGRY after I passed a BIG HUGE WORM, and I am getting less and less hungry the more I get rid of tonnes of little ones. SO, I don't know about your situation, but this is mine....... :)
Take care and let's keep each other posted :)