Do You Burn More Calories When Sick?

Anyone who has been sick (which is pretty much all of us right?) at one point or another, will have noticed that there’s a lot going on with your body.


After all, your body is in overdrive, whether that’s trying to regulate a high temperature, or it’s that snotty nose that won’t stop running.

So does all this effort actually burn any extra calories? If I’m already sick, I’d like to think I could find one silver lining in that big dark irritating cloud. 

Well, If you’re hot and flustered fever-kind-of-sick, then it is likely that your body is burning (pun intended) a fair few extra calories.

Unfortunately, if it’s the bunged-up-nose-kind-of-sick then you won’t be burning all that much more than usual.

However, this kind of illness does tend to suppress your appetite so you may still find yourself in a caloric deficit which can make you shred a pound or two. 

Throughout this article, we’ll delve a little more into just how many calories you’re burning when you’re feeling under the weather. 

Calorie Burning With A Fever

You’ll usually start with a high temperature when your body is trying to improve its immune system.

And the effort it takes your body to do so will raise the number of calories that you’re burning.

So yes, you do burn more calories when you’re sick with an illness that causes a fever. 

But there may be more to play here than just the effort it takes to raise your body temperature.

You may also lose weight through this illness because you are eating less and dehydrated.

We’ve all been there, when you feel that ill, eating and drinking are never really at the top of your priority list. Usually, I just want to sleep. 

Not only this but many other processes in your body can crank up into overdrive because of your immune system response and this can also cause your body to burn extra calories. 

So, just how many calories does a fever burn? There’s not really an exact number that I can give you.

But there is evidence that suggests that for each 0.9 of a degree (F) your temperature raises your basal metabolic rate will increase by around 7%. 

As an example, let’s use Jack. Jack is 25 years old, weighs 150 pounds, and is 5 foot and 8 inches tall.

His BMR at its basic rate is around 1640 calories per day. Jack now has a fever that is 2.7 degrees (F) above usual.

So using the data above, we can work out that he would burn an extra 344 calories per day until his fever subsides. 

But since the evidence, I am referring to does not have strong data to back up these claims, there is a chance that it is slightly inaccurate or based on small sample sizes.

This can only be used as an estimation to give us a rough idea of just how much we are burning. 

Calorie Burning With A Cold


If you don’t have a fever, but instead have come down with a serious case of the sniffles, are you still burning calories?

There wasn’t tons of available data for the information above, and there is unfortunately even less for when you have a cold.

But since your body doesn’t have to work hard to raise your temperature during a cold, it is likely that you will burn fewer calories in this instance. 

That being said, there are other factors that can contribute to your calorie intake when you have a cold.

Firstly, a cold tends to really zap away any appetite you may have.

So boredom eating and snacking tends to reduce massively while you are poorly, which lowers the number of calories that you are consuming. 

It is also possible that while your body tries to fight off infection, you’ll lose a few calories.

This won’t be as high as when you have a fever though. It is hard to compare the difference properly due to the lack of evidence.  

Do You Lose Weight When You’re Sick?

It’s certainly not uncommon to drop a pound or two while you’re poorly, at least temporarily.

However, much of this weight loss is water weight that, unfortunately, will return.

But since you do tend to eat a lot less while you are sick there is a chance that you may lose some body fat or muscle if the amount you’re eating dramatically decreases. 

If you don’t keep on top of topping your body up with fluids, it can also cause dehydration which will cause a loss of water weight.

But there are significant complications that come with dehydration so you should really try to ensure that you are drinking while sick.

Plus the water weight will come back so it’s not in your best interest to try and purposefully try to lose weight in this manner. 

Final Thoughts

While the scientifical evidence is slightly lacking on this topic, there are a lot of indicators that you will lose weight and burn calories while you are sick.

However, there are usually many other contributing factors that cause this other than just your body working harder. 

While having a fever will definitely make your body work harder, and thus burn extra calories, we’re not really completely sure how much this happens.

And if you are sick with a cold, you are likely to burn fewer calories. 

I think that the main contributor is actually the number of calories that you are consuming while sick, which in most cases, is very little.

But even then the weight that we tend to lose is water weight, which alas, does come back.

This is why you may drop a pound or two if you’re ill for a couple of days, then gain it back within a week or two.

Jenna Priestly