My little cookie monster

My son is a growing boy! He is turning 13 in 2 months! He just can't seem to stop eating while at home. Take for example we just finished eating dinner and he had 2 servings. As soon as he is done, he will start opening the cabinet and fridge in search of something else to eat or munch.

When we went for his volleyball tournament last week, I bought him 2 cheese burgers with large fries. He ate at around 3:30pm on our way to the tournament. Once there, after they played their second game, at approximately 6:00pm, he was again begging for more food! He claims that he ate over 2 hours ago and is hungry again. But then he did get some snacks in between games too.

I had my lunch at around 1pm, just one sandwich, and haven't eaten anything till that time. And I'm not hungry. So how could he be hungry? I told him to wait till the end of the game before eating anything heavy, but he was throwing tantrums already. So I bought him a corn dog. I don't really think he is hungry, I think it's more of I'm-bored-I-need-something-to-do/eat. Anyway, after the game, at 8:30pm, he managed to find $2 on the floor, and decided to grab himself another corn dog.

He had gained so much weight already, he is actually overweight for his height already. What should I do? Does your teenage boy eat like this too?

Do you think I should start locking up food around the house like the one that could be bought at I just can't help but think about obesity when I see him eat like that.