Do You Burn More Calories When Sick?

Written by Noleen Arendse

Yes, you can burn more calories when you sick due to increased body temperature. For every 0.5 – 1°C or 1°F increase in body temperature, you can burn 7 – 10% more calories. 

Find out what factors will influence how many calories your burn when sick plus the best foods to eat to support your immune system. 

Do you burn more calories when sick

Table Contents

Do you burn more calories when sick?

Yes, depending on how sick you are. Your Basal Metabolic Rate (the energy your body requires to sustain basic functions), increases by approximately 7-10% for every 0.5 °C or 1 °F above normal body temperature. 

Contrary to the common saying — feed a cold, starve a fever — when sick, it’s best to prioritize rest, hydration and eating a healthy wholesome diet to give your body the best chance to heal and recover.

When sick, weight loss should not be a goal. Any weight that is lost will most likely not be permanent. Once you start eating your standard diet, you’ll probably gain it all back. However, once you’ve recovered, if you’d like to lose weight, read: How many calories should I eat to lose weight?

What is a cold?

The common cold is a viral infection that mainly affects the upper respiratory system, including the nose, throat, and sinuses.  

A cold is usually caused by a group of viruses called rhinoviruses (although other viruses such as coronaviruses, respiratory syncytial virus (RSV), and adenoviruses can also be responsible).

Though common, these viruses are highly contagious and can spread through respiratory droplets when an infected person coughs, sneezes, or talks. They can also be transmitted by touching surfaces contaminated with the virus and then touching the face, particularly the nose or eyes.

Cold symptoms usually include:

  • Runny or stuffy nose
  • Sneezing
  • Sore throat
  • Cough
  • Mild headache
  • Fatigue or mild body aches
  • Mild fever (in some cases)

Cold symptoms usually develop 1-3 days after exposure to the virus and can last for about a week.

Most colds resolve on their own without specific treatment. Rest, hydration, over-the-counter remedies for symptom relief (such as decongestants or throat lozenges), and practicing good hygiene (like washing hands frequently and covering the mouth when coughing or sneezing) is recommended.

What is a fever?

When your body temperature is raised to 100°F (38°C), you have a fever. A fever is a temporary increase in body temperature and is often in response to an infection or illness. It’s your body’s defense mechanism that fights off infections and stimulates the immune system.

The normal body temperature for most people is around 97°F (36.1°C) to 99°F (37.2°C).

When the body detects an infection or inflammation, it releases chemicals which act on the hypothalamus in the brain to raise the body’s temperature set point. This causes an increase in body temperature. 

Common causes of fever include: viral or bacterial infections such as the flu, colds, urinary tract infections, pneumonia, or throat infections. You can also have a fever caused by certain medications, immunizations, inflammatory conditions, or heatstroke.

Symptoms of a fever include:

  • Feeling warm or hot to the touch
  • Chills or shivering
  • Sweating
  • Headache
  • Muscle aches
  • Fatigue or weakness
  • Loss of appetite

While a raised temperature in itself is not dangerous, a very high temperature usually above 103°F or 39.4°C is a cause for concern and it’s best to seek medical attention.

You can burn 7 - 10% more calories per degree Celsius. Normal body temperature is about 97°F (36.1°C) to 99°F (37.2°C). When your temperature is raised to 100°F (38°C), you have a fever. Very high temperature - usually above 103°F or 39.4°C - is a cause for concern and you should seek medical attention.

Do you burn more calories when sick with a cold?

When you have a common cold, your body’s metabolic rate may increase slightly. However the impact on calories burned is minimal because, in most cases, the body temperature is not significant enough to result in a substantial increase in calorie burn.

When you have a cold, you might burn more calories due to factors such as coughing, sneezing, and congestion. However, these extra calories burned are usually modest and unlikely to have a significant impact on overall energy balance.

While you might not burn extra calories, when you’re sick factors such as decreased appetite, reduced physical activity and disrupted sleep can cause a calorie deficit which will result in weight loss. 

Do you burn more calories when sick with a fever?

Yes, you can potentially burn more calories with a fever due to the increase in your metabolic rate. 

While research is quite limited, general consensus is that for 0.5 – 1 °C or 1°F, your body will burn 7 – 10% more calories. For example, if you usually eat 1200 calories, the extra 10% increase will mean an extra 120 calories burned. 

For kids under 16 years, calorie expenditure during a fever can be estimated at 11.3% per °C.

These percentages are general approximations and can vary among individuals. The exact impact on calorie expenditure during a fever depends on factors such as the severity and duration of the fever, individual metabolism, and overall health status.

While you may burn extra calories when you are sick, the focus should not be on weight loss. Rather make sure you eat a healthy wholesome diet, get sufficient rest and drink lots of fluids. Focus on overall recovery and supporting your immune system.

Do you burn more calories when sick with a cold or fever? You will burn minimal calories when you have a cold. However, for a fever, you can burn 7 - 10% more calories for every 0.5 - 1°C or 1°F your temperature increases.

Why do you burn more calories when sick?

When you’re sick, there are several factors that can affect how many calories you burn and weight you might lose.

However, it’s important to note that these changes are generally not significant enough to rely on for weight loss or calorie burning purposes. The focus during illness should be rest and recovery, not weight loss.

 Here are a few factors that will influence the calories burned when sick:

  1. Fever: A fever is an increase in body temperature which can lead to an increase in metabolic rate and calories burned. However, the increase is typically minor and varies depending on the severity of the fever.

  2. Increased heart rate: Certain illnesses and infections might increase your heart rate. Although, once again, the extra calories burned will not be major.

  3. Inflammation and immune response: When your body is fighting off an infection, your immune system becomes more active. This can result in an increase in your metabolism which might lead to a slightly more calories burned.

  4. Decreased appetite: When you’re sick, you might experience a decrease or loss in appetite. This is due to various factors such as nausea, congestion, or fatigue. As a result, you might not eat as much which will result in a calorie deficit. 

While the above factors might result in more calories burned when sick, it’s important to remember that any weight lost might be a combination of fat and water loss. Once you’re back on track with your usual diet, you’ll most likely gain any weight lost when sick. 

You might burn more calories when sick due to: a fever, increased heart rate, an inflammation and immune response or decreased appetite.

Do you burn more calories when sick? Factors that influence

The relationship between sickness, calories burned, and weight loss can be complex and unique to the individual. The impact of the following factors can vary significantly depending on the specific illness, the individual’s overall health, and other factors.

Body size

Your body size and composition will influence how many calories you burn when at rest such as the number of calories burned sleeping. Generally, the bigger the body, the more calories you’ll burn at rest. Larger people will therefore burn more calories when sick compared to smaller people. 

Hormonal differences

Hormones govern most functions in our bodies, including metabolism and calories burned. Variations in hormones between individuals — such as thyroid hormone or cortisol levels — will also affect how many calories you burn when sick. 

The severity of the fever

The higher the fever, the more calories your body will burn due to the increased metabolic rate. Keep in mind, temperatures above 103°F or 39.4°C are cause for concern and you should seek medical attention.

Your appetite

When sick, it is quite common for appetite to decrease. A decrease in calories consumed may result in weight loss simply because you’re eating fewer calories than your body requires. 

Do we need more calories when sick?

In most cases, due to the lack of inactivity, you might not need more calories when sick.

When sick, even though you might not feel like it, it’s important to prioritize healthy eating and hydration. This will help equip your body with the nutrients it needs to help fight the sickness and heal.  

The number of calories burned when sick can vary depending on your height, the severity of your fever, your hormones and your appetite. Generally, due to low activity levels, you don't need to consume more calories when sick.

Foods to eat when you are sick

Prioritizing healthy whole foods is important when you are sick. Also, don’t forget to remain hydrated by drinking lots of water and hot drinks like tea, and lemon ginger and honey.

Here are top foods to eat when you are sick:

Fruits and vegetables

Your body needs essential vitamins, minerals, and antioxidants to support your immune system. Eating a variety of fruits and vegetables will provide your body with the nutrients it needs.


Your body needs protein to repair tissue and boost your immune function. Lean protein sources such as chicken, turkey, fish, tofu or legumes are easy to digest. 

Soups and broths

Warm, soothing soups can help hydrate and provide nourishment. Choose broths or clear soups with vegetables and lean protein. Traditional chicken soup has been shown to have health benefits that help fight cold and flu viruses. 


Honey is well-known for its health benefits and soothing effect on sore throats and coughs. Add it to warm herbal teas or eat it on its own to help relieve symptoms and provide some energy.


Ginger is another staple to help fight colds, flu and infection. Add it to dishes or make ginger tea with honey to help soothe congestion and nausea. 

When choosing foods during illness, it’s important to listen to your body and select options that are easy to tolerate and provide the necessary nutrients for healing.

Remember to stay hydrated by drinking water, herbal teas, or electrolyte-rich fluids such as bone broth.

If you have specific dietary restrictions or need assistance, we recommend that you consult a healthcare professional or a registered dietitian for personalized recommendations.

Eating healthy, wholesome foods is crucial in recovering from illness. Choose a variety of fruits and vegetables, lean proteins, soups and broths, honey and ginger. Remember to stay hydrated to support your recovery.

Foods to avoid when you are sick

There are some foods that you should avoid when you’re sick.

High sugar foods

Foods and beverages that are high in sugar can cause blood sugar spikes and crashes. This can negatively impact your energy levels and immune function.

Sugar can also suppress the absorption of vitamin C — an essential vitamin for your immune system. 


Caffeine can act as a diuretic, which can potentially lead to dehydration. It might also interfere with sleep and rest, which are important for recovery.


Alcohol can dehydrate the body and impair your immune system. This makes it harder for your body to fight off the illness. It can also interrupt sleep and hinder the healing process.


Dairy products — such as milk, cheese, and ice cream — can sometimes contribute to increased mucus production and congestion. This aggravate symptoms in individuals who are already dealing with respiratory issues.

Fatty foods

High-fat foods — such as fried foods and fatty meats — can be harder to digest and may contribute to gastrointestinal discomfort. If you have an upset stomach or nausea, fatty foods can aggravate your condition. 

Hard to digest foods and grains

Certain foods that are difficult to digest, like spicy foods, heavily seasoned foods, or high-fiber grains, can potentially aggravate gastrointestinal symptoms such as bloating, gas, or diarrhea. It’s best to choose easily digestible foods when you’re feeling sick.

The above are general guidelines, if you have specific dietary requirements or intolerances, it’s best to consult your healthcare practitioner for advice. 

To give your body the best chance to heal, avoid high sugar foods, fatty foods, caffeine, alcohol and hard to digest foods.


Yes, if you have a fever, the body can burn between 7 – 10% more calories than normal. Make sure you are eating healthy whole foods and staying hydrated.

For every 0.5 – 1°C or 1°F increase in body temperature, your body can burn between 7 – 10% more calories. 

Yes, being sick, especially with a fever, can increase your metabolic rate. The body needs more energy to support immune system activity and other physiological processes associated with fighting off the illness. This results in a higher metabolic rate.

Several factors can affect the number of calories burned when sick. This includes body size, hormonal differences, the intensity of the fever, and your appetite and activity level. 

Yes, it’s possible to experience weight loss when you’re sick. But it depends on several factors such as decreased appetite, fluid loss, increased metabolism, and potential muscle wasting. However, any weight loss during illness is usually temporary and is mostly related to fluid loss, decreased food intake, and potential muscle wasting.

Overall Summary

  • Do you burn more calories when sick? Yes, you can however it does depend on several factors
  • Aim to eat healthy whole foods to give your body the essential vitamins and minerals you need to recover
  • Don’t forget to stay hydrated by drinking lots of water, soups and warm drinks