It could be diet, it could also be partially genetic, or your specific activities/lifestyle. I'm also hungry all the time. I'm a bit hyperthyroid because of some issues with my mom while she was carrying me so that's part of it.
There is no way I can go 4-6 hours after a meal with no hunger unless I absolutely stuff myself, and that just aint good. I eat almost every 2 hrs. I wake up starving almost every morning.