There are many reasons a child may appear to overeat. Children with ADHD need a lot of calories for their high activity. But the medicines used to manage ADHD usually make it hard for them to eat, especially lunch. This means they need to ea t more at some other time of the day. Rarely the medicines used for ADHD and more often medications for depression or anxiety actually cause an increase in appetite. There are even more rare conditions such as over active thyroid that cause hyperacivity and over eating without weight gain. Finally some children over eat to make up for not feeling they are gettting enough attention or care. Ask your child's doctor if any of these factors are causing overeating that needs to be addressed.