exacly how much and what are you eating? everyone has a different idea of what it means to be hungry all the time.
if your eating lower calories foods like veggies/fruiits and low fat stuff all the time and not eating much with substance no wonder your hungry. your body is looking for nutrients that your not getting. second you could be insulin resistant. if you are your cells require a high blood glucose level to somewhat overcome the glucose intolerance aka insulin resistance. in other words as the glucose levels are drawn down the cells run out because the concentration fell below osmosis levels and are crying for glucose even if yur blood sugars are in the normal range.
you also could be eating mostly junk food for all I know. high gi foods is exactly what someone needs if they are insulin resistant ot overcome the resistance. also high and lows of glucose levels can spark hunger as the brain picks up the swings (even if they are within normal range) because they are happening to fast. so there is a lot of reasons why someone would want to eat all the time.
I have been following stephanie seneff information on glucose fructose and obesity epidemic. google her name and read her blog or type in the search the obesity epidemic is metabolic syndrome a nutritional defiency. been following this for a little over a year. check it out.