My understanding is on a prolonged sub-maintenance (I assume by this you mean a fixed cal level which wa initially sub) your metabolic rate will drop to match your calorie intake. Thats it.

Have a look at the Avantlabs site in their magazine, they have a 4 or maybe five part article on leptin, but basically if your body believes it is in a fed state leptin will rebound, hence refeeds trick your body for a short period.

Something like that anyway