This kind of hunger is what I've felt my whole life too, though my weight is still only in the overweight category. I can eat twice, three times what a normal portion is and still feel like I need to eat. I could easily eat multiple large pizzas by myself with no problem at all. There's a scene from The West Wing where the chief of staff describes his alcoholism and how people would ask him how could he drink so much and still want more. His answer is that he doesn't understand how anybody else could not want more. That it's the best thing in the world. And that's exactly how food feels to me.
A year ago I was diagnosed with ADHD (inattentive) and prescribed a very low dose of Vyvanse (amphetamine based). Suddenly it was gone. I'd want to eat at normal times, I'd eat a normal portion but I could easily walk away or I actually just didn't want more. I asked my wife, is this what other people feel like? It really rocked my world a bit. It's one thing to logically know that people experience reality differently, but I've rarely had such a stark example of it.