Do You Burn More Calories When Sick?

Being sick is never fun, and some people wonder whether you actually burn more calories when you’re sick. In theory, it makes sense that you would. When you’re sick, you’re more tired. This is because your body is working extra hard to fight the infection or virus.

This is particularly true when you have a fever. Since your body temperature goes up, your metabolism increases — this is just your immune system’s way of fighting through the sickness. This means that you may have to eat and drink more while you’re sick in order to make up for the calories and nutrients that your body is quickly using up.

In this article, we’ll be talking about how and why you burn more calories when you’re sick, so stick around! As always, Revive MD is here to answer all of your (calorie) burning questions (forgive the pun). Let’s get started!

Debunking the Myth: “Feed a Cold, Starve a Fever”

Sayings are usually age-old, but "feed a cold, starve a fever" is one supposed maxim that should be put to rest. This saying comes from a dictionary published by John Withals in 1574, which stated that fasting is an excellent cure for fever.

This saying, perhaps, stems from the common belief that eating food can help the body produce heat when it’s "cold," and avoiding food can help it cool down when it’s overheated. However, recent medicine says that the saying really should be "feed a cold, feed a fever.” When your body is fighting disease, it needs energy, so eating healthy foods is one of the best things you can do.

When you're sick, your body works harder than usual, especially when you have a fever. To fight off the illness, your immune system kicks into high gear, which means your metabolism speeds up. Studies show that having a fever increases your body’s energy needs, so it starts tapping into its calorie reserves (Waldron & Connell, 2020). That’s why you might feel hungrier when you're under the weather—your body isn't just keeping up with its usual tasks; it’s also using extra energy to help you recover.

Eating can also help the body generate heat — although an extra layer of clothing or bundling yourself up in a blanket can also help keep you warm. There’s no need to eat too much, though, because the body will quickly convert newly digested food into energy. The body is also quite efficient at converting stored energy into fat.

Now, what about when you have a fever? A fever is part of the immune system's attempt to fight off viruses and bugs. It raises your body temperature, which increases your metabolism. This means that you’re burning more calories when you have a fever. Every time your body temperature goes up, energy demand continues to increase. This is why it’s important to eat a lot of calories when you have a fever.

It's even more important to drink fluids. A fever dehydrates your body, in part due to the increased sweating that occurs with a high body temperature. Therefore, it’s important that you drink a lot of water (perhaps more than you usually would) when you have a fever. The same applies to fighting colds.

Dehydration also dries up mucus in the nose, throat, and lungs, which can clog the sinuses and airways. As the mucus hardens, it becomes more difficult to cough, which is our way of expelling mucus and bacteria. Hydration helps keep mucus flowing, which is one of our natural defense mechanisms (even though it can be a bit disgusting).

The challenge, of course, is that when you're sick, you don’t have much of an appetite. You might be thirsty, but if you’re really feeling bad, you might not have the energy to drink as much water as you should. Interestingly, loss of appetite is common in people with viruses. It may actually be part of the body's attempt to direct its energy toward killing pathogens.

How Does the Body Burn Calories When Sick?

You may develop a fever when you’re sick, which is the body's normal response to foreign organisms that cause illness. Studies have shown that energy consumption increases by 10% with each increase in body temperature. This increase in energy expenditure means that the body needs more fuel, which, of course, can come in the form of calories.

In addition to fever, inflammation also speeds up your metabolism when you’re sick. When you’re inflamed, your body releases chemicals that help fight off illness. These chemicals increase your energy needs to keep your immune system working well (Dinarello, 2018). This heightened inflammation response requires more calories to maintain the body’s defense mechanisms.

When you don't want to eat (due to illness), the body uses stored energy in the form of fat or muscle mass as fuel. Several case studies in adults have reported weight loss associated with fever — probably because the illnesses that these adults were dealing with caused them to have a lack of appetite.

Do you burn more calories when sick with a cold?

You won’t always develop a fever when you get sick. This doesn’t make the common cold any less nasty to deal with, though. The common cold can still cause a lack of appetite, which makes sense — when you feel crummy, you just don’t want to eat. Some people wonder whether you burn more calories when you’re sick with a cold, just like you do with a fever.

When you have a cold, your body's metabolism may increase a bit. However, the effect on calories burned is generally pretty minimal because, most of the time, your body temperature won’t be high enough to burn calories. That said, when you have a cold, you may burn more calories from symptoms like coughing, sneezing, and congestion. However, any extra calories burned due to common cold symptoms are usually quite modest.

Although you may not be burning excess calories due to an increase in body temperature, factors such as decreased appetite, reduced physical activity, and sleep disturbances when you are sick can create a calorie deficit that leads to weight loss. Just like when you have a fever, it’s important that you eat a balanced diet and drink plenty of water when you have a cold!

Why Do You Burn More Calories When Sick?

When you're sick, a number of factors can affect how many calories you burn and how much weight you lose. Of course, you shouldn’t rely on your illness to “help” you lose weight. That’s just playing with fire.

During illness, your focus should be on rest and recovery, not weight loss. Let’s take a closer look at some factors that affect calories burned when sick below:

Fever

Fever is an increase in body temperature that can make the metabolism work harder — which means, more calories get burned. Research shows that for every 1°C increase in body temperature, energy expenditure increases by about 10-13%. This is due to the body’s need to fight infection and maintain a higher metabolic rate. The increase in metabolism is usually small, though, so the amount of calories you burn when sick will depend on how severe your fever is.

Increased heart rate

Certain diseases and infections can make your heart beat faster. You won’t burn a huge amount of calories just because your heart is beating faster, though. In fact, unless your situation is extreme, the amount of calories that you’ll usually burn due to an increased heart rate is pretty insignificant.

Inflammation and the immune response

When your body is fighting an infection, your immune system gets activated. This can lead to an increase in metabolism, which, as we now know, can result in slightly more calories being burned.

Decreased appetite

When you’re sick, you may feel like you don’t have much of an appetite. Loss of appetite can be caused by a number of things, but nausea, congestion, and fatigue are the usual culprits. As a result, you may not eat as much, which could potentially cause you to lose weight. Once you feel better and get your appetite back, though, you’ll likely gain that weight back.

How Taking Supplements Could Help Boost Your Immune System

Getting a cold, the flu or a virus is the worst. While seasonal sniffles are sometimes unavoidable, there are some things you can do to prevent the spread of the disease when flu season arrives. For example, taking immune supplements proactively can reduce the likelihood of catching a cold in the first place.

For example, vitamin C is an essential dietary supplement that supports the immune system. Evidence suggests that vitamin C can help modulate and resolve inflammation, fight infection, and promote tissue repair.

Supplemental vitamin C can also help prevent and reduce the severity of respiratory infections. Revive MD has a great vitamin C supplement available if you’re interested in boosting your immune system.

Vitamin D is another vitamin that can help protect against respiratory infections. This nutrient contributes to the function of immune cells, including T cells and macrophages, which protect our bodies against pathogens.

A 2017 study found that individuals deficient in Vitamin D were more susceptible to respiratory infections, highlighting the importance of maintaining healthy levels of this nutrient. In fact, about 42% of Americans are vitamin D deficient. If you’re interested in whether or not you belong to this group, talk to your doctor. If you do happen to have a vitamin D deficiency, then taking a vitamin D supplement might be the right choice for you.

The Best Foods to Eat When You’re Sick

When you’re sick, it’s important that you nourish your body with lots of healthy foods. It’s also super important that you stay hydrated by drinking plenty of water and warm drinks, like tea with lemon and honey. Let’s take a look at some of the best foods to eat when you’re sick below:

Fruits and vegetables

Your body needs essential vitamins, minerals, and antioxidants to support your immune system. Eating plenty of fruits and vegetables when you’re sick will provide your body with the nutrients it needs, which may speed up the healing process.

Protein

Protein-rich foods like chicken soup, tofu, or fish are commonly recommended when you’re sick because they’re easy to digest and help provide nutrients to the body. Protein is also crucial for immune function. Research has shown that people who consume enough protein experience better immune responses due to amino acids’ role in producing antibodies and immune cells (Calder, 2020).

Soups and broths

Is there anything more comforting than chicken soup when you’re sick? Warm, soothing soups can help hydrate and nourish your body when you’re not feeling well. We’d recommend choosing broths or clear soups with vegetables and lean proteins.

Balancing Nutrition When Appetite is Low

When you're not feeling well and don’t have much of an appetite, it’s still important to get the nutrients your body needs. Here are some simple tips to help you maintain balanced nutrition:

• Choose nutrient-dense, easy-to-digest foods: Smoothies with fruits, veggies, and protein powder. Soups can also be a good option if they’re rich in vitamins and minerals.
• Include protein-rich options: Lean meats, tofu, beans, and protein powder can support recovery.
• Go for soft and gentle foods: Applesauce, plain toast, oatmeal, and scrambled eggs are easy on the stomach.
• Stay hydrated: Drink broths, herbal teas, or flavored water with fruits.
• Eat small, frequent meals: Snacks like fruit, crackers, or small servings of soup can be easier to manage.
• Use nutritional shakes if needed: Meal replacement drinks can help ensure you’re getting essential nutrients when solid foods are too challenging.
• Incorporate supplements: If your appetite is very low, consider taking a daily multivitamin or specific supplements to cover any nutritional gaps. Always check with a healthcare provider before starting new supplements.

Strengthen Your Immune System With Revive’s Supplements Today

Revive MD is here to support you when you’re down with a cold, the flu, or a fever. We offer plenty of supplements that are specifically designed to strengthen your immune system, like vitamin C and vitamin D supplements.

Remember, supplements aren’t a replacement for the food you should be eating when you’re sick (lean proteins, vegetables, and fruits). They can, however, give you the extra boost you need to get through your illness.

Head on over to the Revive MD website today, and check out our selection of immune-boosting supplements. You never know when you could catch a cold or run a fever, so it’s always best to be as prepared as possible!