keep warm in an insulated bag or cooler

Can you keep warm in a cooler or an insulated lunch bag?

Wondering if you can keep warm in an insulated bag or cooler? Can you keep your meals warm like you keep your meals cool?

The answer is yes, you can keep warm in a cooler or a cooler bag. In fact, the same thermal insulation used to keep cold is used to keep warm. Heat can be trapped to keep your food at the temperature of your choice.

However, there are a few extra steps, precautions and things to know. You can use a cooler to keep food warm and cold and there are several tips and tricks to do this. However, there is one important thing you need to watch out for when keeping warm food in a cooler. You don't want to keep them just warm to prevent them from becoming a breeding ground for bacteria.

So, to keep food safe and healthy, you should try to keep it very warm. So, we're going to take a closer look at how to do all of this right now.

In this article, you will learn the following things:
  • How you can keep the heat in your cooler
  • Simple tips to keep your cooler warm
  • How long you can keep your food warm

Let's not waste any more time, let's go!


How to keep your meal warm in a cooler?

cooler for warm meal

Most of us think that a cooler is a device that only keeps food and drinks cool. Especially with high performance coolers that can keep ice for over a week. When it comes to coolers, insulated bags, lunch bags or even insulated bags, we usually only think about the cold.

However, coolers don't really care if your food and drinks are warm or cold inside. They only do one thing: keep the temperature of what you put inside them. So it is through a process of thermal insulation that rigid coolers or soft coolers will work to keep the temperature you want.

The insulated lunch bag is insulated with foam that contains millions of tiny air bubbles. This makes it very difficult for heat to pass through the walls of your cooler.

When you have cold items in your cooler, it prevents the outside heat from entering your cooler and warming the ice inside. On the other hand, when you have warm food in your cooler, these isothermal walls work the same way to keep the inside heat from moving outside.

By the same token, heat can't easily move through the walls, so it stays trapped inside the cooler, keeping your food warm longer.

However, coolers aren't perfect, so food will eventually get cold, but it can stay warm for hours or even days in the right cooler and by following the tips we're about to outline.


Tips for keeping warm in your cooler or cooler bag

Lunch Bag

When you put ice packs or just ice in a cooler, you usually just put the ice and what you want to keep cool in it and you're done. And, for more information, you can read our blog post on how to keep cold long in your cooler bag. However, if you want to keep warm food for a long time in your cooler (without making the cooler light up, warp or break), a few more steps are needed. We're going to reveal the tricks to keeping your meals warm anywhere!

Now we're going to give you 5 effective tips for keeping your food warm in your cooler :


  • Buy a quality cooler

First of all, the quality of your cooler makes a difference. High-end coolers like a Yeti cooler will keep food warm much longer than a cheap $20 cooler you bought at your local hardware store or big box store. The better the cooler is at keeping ice, the better it will be at keeping food warm.

The same is true for insulated bags or Healthy Lunch insulated backpacks. Our thermal backpacks are great for keeping things cool, but also warm! Discover our collection of insulated backpacks, we offer a wide range adapted to your desires and needs.


  • Preheat your cooler

At room temperature, the walls of your cooler will be cold compared to your food. This can instantly cause your food to lose a lot of heat when you put it inside.

A simple trick to overcome this problem is to first preheat the walls of your insulated compartment. Wondering how to heat my cooler? It is very simple! Simply fill your cooler with warm tap water and let it sit for 30 minutes to 2 hours.

Then, discard the water, dry your cooler and fill it with your warm food.

This is the same for an insulated lunch bag or a backpack cooler. This is a great way to keep your food and drinks warm.


  • Cover your cooler with aluminum foil

This is the second tip for keeping warm. Thermal coolers are very good at stopping two types of heat transfer - convection and conduction - but they are not designed to stop heat radiation from escaping your cooler.

Heat radiation can travel in a vacuum and pass through a cooler, which will automatically cause your food to cool.

But fortunately, aluminum is an excellent reflector of heat radiation. It has a reflection of about 97-98%.

So by lining your cooler with aluminum foil, you add an extra layer of insulation that keeps your food warmer for longer. Again, this trick also works great for any other type of cooler bag.


  • Add a hot water bottle, heating pad or hot bricks

Some foods, like soups, are very dense and contain a lot of heat energy. However, other foods that are not as dense have difficulty staying warm for long periods of time.

Often, for these types of foods, it is important to add another heat source to keep your meals warm. This will ensure that you are not relying solely on the heat energy of the food itself.

Hot water bottles are a very easy way to do this because they are very dense and contain a lot of heat energy and when you fill them with boiling water, they can get very warm.

Wrapping bricks in foil and placing them on top is another good way to add a heating element to your cooler. However, the weight will be much greater. You can choose other heat conserving items to keep warm.

In a small lunch bag, we'd recommend the hot water bottle trick. In terms of heat/weight ratio and simplicity of installation, it is the best tip.

water kettle for keep warm


  • Use towels, cardboard or paper to insulate and fill the space in your cooler or bag

Super hot food containers, hot bricks or even hot water bottles can get so warm that they damage the plastic of your cooler or insulated lunch bag. Sometimes, it can even melt the insulating part of your insulated lunch bag.

In order to counteract these inconveniences, we suggest you follow these tips.

Place a towel or cloth at the bottom of your cooler to both insulate your food and protect the cooler from heat damage. You can use towels to put on all the inside sides of your cooler.

Also use towels, cardboard or crumpled newspaper to fill the air spaces in the cooler. This is because the air in your cooler bag will cause the heat kept inside to escape. Simply filling your cooler completely with insulating materials or food will keep the heat in your insulated portion of the bag more effectively.


How long can you keep warm food in a cooler?

how long keep warm

If you prepare your cooler properly and follow the steps above, adding hot bricks or a hot water bottle, it is possible to keep warm food in a cooler for up to 24 hours (depending on the quality of the cooler).

However, if you don't prepare your cooler properly for the type and amount of food you have, your food may get cold much faster in just a few hours.

High quality coolers with thick insulated walls are able to retain heat better and keep food warm much longer than a cheap cooler. So a Healthy Lunch cooler bag or equivalent will work much better than a cheap one.


Can you put warm water in a cooler?

You may think it's a good idea to put boiling water in a cooler to heat it up to keep your food warm. However, this is not recommended at all. Stick to only putting warm water that is less than 80°C.

Boiling water can distort the inside of the cooler and cause the plastic to crack. It would be a shame to waste the investment you made in your cooler bag.

Cooler bags are often inferior to rigid coolers in terms of performance, but they are much more convenient to carry. To keep your food warm without damaging your bag, we recommend wrapping your food in aluminum foil and a towel. This will keep your food warm and you won't risk damaging your cooler bag. In addition, a stainless steel or insulated lunch box can be a very good alternative to take your lunch in a Healthy Lunch bag.

Cooler Backpack

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