Get a vacuum-insulated food jar

A vacuum-insulated food jar is the best way to keep food fresh all day without ice packs.

Soft lunch bags are basically insulated blankets. They just slow down temperature change; they don’t actually hold cold. That’s why every one of them tells you to add a frozen gel pack. Without one, your sandwich is sitting at room temperature by 10am, and that’s not great for anything perishable.

A vacuum-insulated jar works differently. There’s a vacuum between the walls, so heat doesn’t get in or out. Put cold food in a pre-chilled jar and it stays properly cold for six to eight hours. Put hot soup in and it stays hot. It’s a thermos for solid food, basically.

Look for the Hydro Flask Food Jar, Stanley Master Unbreakable Food Jar, or Zojirushi Mr. Bento if you want separate compartments. Pre-chill the jar with ice water before adding your lunch, then dump the water out. That makes a bigger difference than people expect.

This is not a sandwich-and-chips setup, though. It works best for one-dish meals like salads, stews, grain bowls, or cold pasta. If you’re packing a picnic-style lunch, just use ice packs like a normal person.