Why does my stomach feel hungry even after eating?

When I can feel physical hunger and even nausea from hunger I am able to snack and eat but still feel hungry even after the meal (not because my brain hasn't yet received that I've eaten, but even after that) and this always leads me to constantly snacking and overeating (I also exercise a lot) and eating... show more When I can feel physical hunger and even nausea from hunger I am able to snack and eat but still feel hungry even after the meal (not because my brain hasn't yet received that I've eaten, but even after that) and this always leads me to constantly snacking and overeating (I also exercise a lot) and eating lots of calories while low calorie foods no matter the volume never seem to fill me up. I don't know if this is due to something like a stomach ulcer, but up until now I had a habit to binge and purge (not too or very often) but how can I solve this constant hunger without going to my gp?