I wanted to add one other thing about eating in the absence of hunger. I think if someone generally "cleans their plate" when eating, that this is a sign of disassociated eating. In other words, if a person sits down to eat and is truly guided by hunger, then what are the odds that the food on the plate is exactly the right amount to fill them up? The amount of food on the plate is somewhat standard, while the variables affecting hunger – sleep, exercise, stress, size of previous meal – are all variable.
I think it would be a far better sign if a person sometimes leaves food on the plate, and then other times eats everything on the plate and asks for more. And of course, sometime the amount on the plate will end up equaling the amount of food a person is truly hungry for.
But again, I think this would be quite a coincidence if this happened every meal, every time.