Don't Buy a 'Microwave-Safe Insulated Lunch Box

The honest answer is that a single lunch box that’s genuinely insulated and microwave-safe is a gimmick, and you’re better off with two pieces.

Insulation works by trapping air — or in some cases, a vacuum or foam. Microwaves heat your food, not that trapped layer. So when you microwave a double-wall insulated plastic box, that air gap can heat unevenly, warp, or even melt. And if the insulation is foam or metal, it’s a hard no in the microwave. Products that claim both usually do neither well.

Instead, get a normal insulated lunch bag or cooler-style bag, and pack your food in a microwave-safe container. Reheat at work, then drop the container back in the bag to keep it warm. Or, if you want food to stay hot for hours without a microwave, get a thermos-style insulated food jar and just don’t microwave it.

Separating the jobs is the only way you get both without holding your breath at 900 watts.