My solution would be just to not buy the crappy food for him anymore.  He can take healthy food for lunch and buy crap at school with his own money.

But congrats on your win.

Awesome idea and kudos to you for some well deserved peace of mind!

Key or code?

If it's a key, make sure you have it on you at ALL times

This is great! I've been tempted to do something similar, trust me. SS goes in waves, sometimes he will just eat all the snacks and it makes me so mad. A brand-new package of something will be gone in 1 day. I buy most of the groceries, so it's even more infuriating.

2 nights ago I bought a package of Oreos for skids lunches and for my SO. I brought it into the house at 6:30pm, when I got home from the gym. The next night at 6pm, I looked in the cabinet and noticed the package was partially open, because that's what skids do- open cookies, crackers, cereal, and leave it WIDE open in the cabinet to immediately get stale and old, like a bunch of savages. Anyway, I glanced in the package and 2 of the 3 rows were already gone! In 1 day, and skids were at school during the day! Which means someone snuck them at night, or after school. SS was there and I said, wtf, who ate all the Oreos?? He said, I only had 1, just now (Mmm, sure SS). I assumed it was my SO, but I mentioned it to him last night and he said he hadn't had any at all. So you're telling me SD9 ate 2 entire rows of Oreos herself, in 1 day? She's not like that, she usually asks if she can have a snack, and even asks how many she can have. I told my SO that SS had to have eaten most of them, and that it pissed me off that he lied to me. Skids came in the room and my SO actually asked skids, Ok, what happened to all the Oreos? (this is huge progress, typically he wouldn't even ask, but he has been trying to be better about addressing things with skids that bother me). It wouldn't even be a big deal, but this ALWAYS happens when I buy cookies, someone eats the entire package in 1 day. SS denied, said he only had 2 cookies, SD said she only had 3 for lunch. Someone is lying, but I just said, look, I'm not even trying to make a big deal out of it, but if we have snacks like that, you only eat a normal portion size, not 2 rows...and because of this, I won't be buying cookies anymore.

So that's my solution, I'm just not buying them anymore. I'll buy chocolate for myself and continue to hide it in nondescript boxes on the top shelf where they won't even look. Did that work out the way you wanted it to skids? Nope. Hope they enjoy their new cookie-less existence.

Cooooookies, I had to hide the junk food in a locked room. I no longer bought junk prior to skid weekends - I bought it the following Monday because I'm evil like that. It was so bad, that DH started moving the junk food to the locked room before the skid invasion. This is what happens when kids are addicted to sugar (and salt).

I learned to lock things up within the first year of step life. Skid24 moves back today and I already have installed a keyed lock on my bedroom and the furnace room where my deep freeze and beer fridge is located. Anything I don’t want him to touch will got into the furnace room. 

I don’t care if DH doesn’t like it but it helps keep the peace since Disney dad sometimes has issues saying anything to his kid. 

My SS14 is a food thief. So much so that I had to put zip ties on our pantry and fridge. We don't buy any junk really. But after coming down one night for water, he was busted in a big tub of raw cookie dough with his nubby, nasty fingers. We had bought it for Christmas cookies from a wholesale store and I threw the whole thing away. 

... save your money folks, and just hide the goodies under the veggies in the fridge veggie-drawer.

Worked like a charm for me when SS18 still lived with us. 

Locks are the answer!

I locked up stuff (makeup / bathroom things) from SDs when SD14 (then 10/11) couldn't keep out of my stuff when explicitly told not too - then SD12 (then 9/10) and her friend got into my things.  DH didn't care ("they're just kids"!  Me:  destroying $20 eyeliners...you now owe me about $50 for new makeup!) and SD12's troublesome friend's mother just said, "Oh, she does that."  WTF?

I also have two large cabinets in the laundry room that I installed locks on.  I haven't had to lock them up since SD14 stopped coming and SD12's troublesome friend hardly ever comes over any longer.  But those locks on the cabinets saved me a lot of $!

Made my life so much better!!!!!! It was a small change in action and a big change in attitude. Reading Steptalk and learning how others are coping. Another small change in action and big change in attitude!!!!

Sharing what I have learned with others about Narcissistic children-who-then-become-narcissistic-adults has made a big difference. Once I learned about this, it was a "game-changer". Because now I can anticipate better, protect myself and DH better. Be a better SM to Munchkin SD12. 

It can get worse. SS34 entered our home without permission and either drank or absconded with 5 1.7 liters of booze.  All of the bottles were unopened (we don’t drink hard liquor) and all were left with 1/2 inch.   We’d been planning to entering which is why we’d stocked our bar.