My 13 yo boy is always hungry (very tall and slim, sporty) I let him have cereal for breakfast and before bed too if he wants it and sometimes after school for a snack. I don't buy any cereal which has over 20g/100g sugar. My DH thinks its too much sugary cereal. DS doesn't eat well at school but has a cooked from scratch family supper every day, and snacks on everything, fruit and raw vegetables included. How much is too much, mners? thanks!