Hey mate! Im glad to know I'm not the only one with a weetbix addiction haha
Im a 18yo GIRL and i can eat around the same as you, though im not overweight! Im quite athletic so i think my body just constantly requires carbohydrates. There could be several underlying causes to your weetbix eating frenzies. The more obvious causes could be die to diet, excersise level, stress, physical changes (growth) or just boredom. I seem to suffer most at night whilst watching television. However, in itself Weetbix is quite healthy 97% wolegrains and low GI as well as no artificial sweeteners or colors.Seeing that you are living in a first world country i highly doubt you have a parasite 'stealing' your food, unless of course you have travelled abroad recently?