Get a good insulated bag and two ice packs

Keeping food cold for 8 hours is about insulation and thermal mass, not the lunch box itself. Any decent cooler bag will do — the real trick is having enough ice.

No regular lunch box stays cold on its own. You need ice packs, and you need enough of them. Two medium packs — one under the food, one on top — work better than one big one because they surround the food and trap cold air.

What actually matters in the bag: thick insulation (not just a shiny liner), a good zipper that doesn’t leak air, and a shape that holds your containers plus the ice packs. Most soft-sided cooler totes are fine. Fancy hard-shell boxes are not automatically better.

Also, pre-chill the bag itself. Stick it in the fridge overnight with the ice packs inside. That way the bag isn’t stealing cold from your lunch during the first hour.

And don’t waste money on “self-cooling” gadgets or special gels. A solid insulated bag and two freezer packs will beat most gimmicks. If you’re going to trust it with your lunch, the ice packs are the real workhorses.