The only lunch box that stops thieves is a lockable one.

The only lunch box that reliably prevents office food theft is a lockable one, and there are a few good choices depending on how much you want to spend.

A regular insulated bag or plastic container is just a welcome mat. Anyone can unzip it or pop the lid. If you’re dealing with a repeat offender, the barrier has to be real — not just a nod to politeness.

Cheapest fix: get a small padlock and run it through the zipper pulls on any lunch bag. That works. But you’ll look a bit weird unlocking your lunch at noon. Slightly better are lunch boxes with built-in combination locks — they’re out there, mostly from backpack-style lunch makers. They’re not huge, they fit a bento container, and they send a clear message: this person isn’t messing around.

Hard-sided lockable cases are even more secure, but they’re bulky and overkill for an office fridge. Also, remember the other half of the problem: making your lunch look unappealing. A locked bag that’s also a plain, grimy brown bag says “not worth the effort.” But honestly, the lock is what does the work.

If someone’s willing to crack a combination lock for your leftover pasta, that’s on them.