When the weather is cold, or when you want to take some leftovers from last night to work or school for lunch you might want to know how to keep food warm in a lunch box.
Keeping food cold in a lunch box is a lot easier. Throw the food in an insulated lunch box with an ice pack and you're good to go.
But unfortunately trying to keep food warm is harder than trying to keep food cold.
Food looses it's heat fairly quickly, especially in a lunch box. You also generally want to keep one item of food warm while not warming up everything else in your lunch box so that can be tricky too.
But luckily there are a few different techniques you can use so that you can keep food warm in a lunch box so it's super hot and tasty when it comes time to eat it.
Hands down the easiest and most effective way to keep food warm is to use a thermos or an insulated flask.
These are made of double walled stainless steel with vacuum insulation which is one of the best insulators at trapping heat.
It will keep the food inside the flask warm while the outside of the flask will stay cool so it won't warm everything else up in your lunch box.
The downside to this is the round shape and small size of the flask can make it difficult to fit in leftover food that isn't soup so you might want to try some other techniques for mom's lasagne.
2. Insulated Lunch Box
For the life of me I couldn't find any lunch boxes that were vacuum insulated. However I did find the Omie Box which is a colorful plastic bento lunch box with a vacuum insulated compartment for warm food.
It's called the Omie Box and it's pretty cool looking and not too expensive.
This would be great for keeping food warm for kids.
If you don't want to go to the effort and expense of buying a dedicated lunch box like the one above then a simple insulated lunch box will do the job just fine.
Put your food in a plastic container, wrap the container in aluminium foil and a tea towel and then place in an insulated lunch box to keep it cold for hours.
It won't work as well as an insulated thermos but it'll still do the trick.
3. Aluminium Foil + Tea Towel
Aluminium is an excellent insulator of radiation heat and it is also a great way to keep hot water in your food from evaporating and taking all the heat with it.
If you want to keep your food hotter for longer then wrap it in aluminium foil and then wrap a small towel around your food to further insulate it.
This will keep your lunch warm until you're ready to eat it without warming up everything inside your bag.
4. Mini Hot Water Bottle or Heat Pack
Rather than just relying on the food itself to stay hot you can add a heat source into your lunch box or lunch bag to help keep it warm.
You can use something like a wheat pack or rice pack and warm that up in the microwave and put it in your lunch box.
Or you can use a water bottle and fill it up with warm or hot water and use it to keep food warm in your lunch box.
Don't use a double insulated bottle though as no heat will get through to your food.
Instead use a plastic bottle (be careful of melting) or use a single walled stainless steel bottle as the heat will pass through it to your food.
Below is a link to a cheap 4 pack of single walled stainless steel bottles in multiple sizes. One of them will surely suit your needs.
5. Paper Towel In Thermos To Keep Things Dry
Sometimes keeping things in a thermos doesn't work well because the moisture ruins the food and makes it all soggy.
Chicken nuggets are a great example of this.
The simple solution here is to simply get creative and put some dry paper towels in your thermos and then put in your food. The paper towels will soak up the moisture without your food losing it's heat.
6. Insulated Bags
You can buy reusable insulated bags that help to trap in heat and keep items either hot or cold for a few hours until lunch time.
Simply place your food item in them, zip lock them closed and you're good to go.
They won't work nearly as well as a thermos but they are great solutions for kids to take hot things to school and you can wash them out and reuse them when they are done.
7. Hot Glass Tupperware (In Alfoil)
Glass tupperware can actually absorb and retain a fair amount of heat. It can also lose that heat quite quickly if it isn't insulated with something else.
For this technique pour some boiling water into your glass tupperware container to heat up the glass.
Tip out the water, dry the container and quickly put in your hot food and close the lid.
Now wrap your hot tupperware in some aluminium foil and a towel to trap all that heat it.
Now your food will stay hot in your lunch box for hours.
8. Instant Hand Warmers
For a simple heat source when you're on the go you can use instant hand warmers. Shake them in order to activate them and then place them in your insulated lunch box with your food.
The good thing about these is that as they start to cool down you can refresh your lunch with a new one and still provide that external heat source.
However, hot water from a tap in a water bottle can do something similar for a lot cheaper. Still this is an option.
9. Wrap In A Fleece Sweater
Fleece sweaters or puffer jackets are amazing at keeping humans warm but they also work well to keep food warm too.
Wrap your food in a fleece sweater, puffer jacket or any other type of warm clothing in order to trap the heat it and keep it warm.
Then you can wear your sweater after lunch if you need to.
10. Keep Hot Water and Make On Site
Another technique to have a hot lunch is to fill up something like a Hydro Flask bottle with boiling water in the morning and put it in your bag.
Then at lunchtime use the boiling water to heat up a cup of noodles, make a cup of soup or anything else you can make with boiling water.
It's a much easier way to keep things hot and it's a lot less messy than trying to pack warm pasta into a lunch bag.
Hydro Flasks are great at insulating and there are also a lot of other different brands out there.