I would like to offer my support for OP.

I have a similar situation with my 11 year old DS. He sneaks food all the time. I have no problem with him having snacks and candy in moderation, but he just can't stop himself from eating entire boxes of snack foods or entire bags of candy. We find piles of wrappers under his bed. We even found empty sugar packets in his room!
My DS knows we allow him a treat every day after dinner. He picks the treat. I buy foods he likes. He also usually takes a piece of candy each day in his lunch. He is allowed to have pop on the weekends. It doesn't matter. He is still the kid at the school parties stuffing his face with all the treats he can. The teachers probably assume we don't allow him sugar at home. I think people assume too much. Teachers think they can tell the child who can't have treats at home.

Are they in my home watching what my child eats? I don't think so. Both my boys are raised the same as far as what they can eat. Only one of my boys stuffs his face with junk at every opportunity. Maybe people should stop assuming they know what goes on in everyone's home!
This was becoming a huge problem. He was sneaking around eating all this junk, and then not eating his dinner. I can't imagine what all the sugar was doing to his teeth. He put on a lot of weight in the last year too. We thought if we eliminate everything it would become the forbidden fruit situation that everyone is talking about. Well, we ended up doing just that. We put a lock on a pantry in the basement, and all the snacks and treats are now in that closet. DS knows he can ask me for the key and get a snack or treat each day, but I found that he rarely asks me for it. I guess out of sight out of mind.
It really bothers me that I can't trust him with junk food in the house, but I also try to look at it from his point of view. I have a hard time not eating junk too. So I made it easier for him to follow the rules by taking away the temptation. I chose to lock it up rather than not have it at all because we will still eat it in moderation. I do see your point about beer. We lock up our alcohol too. I never took alcohol from my parents, but who know what my kids will do. They are good kids, but sometimes good kids make bad choices.