Fever and Metabolism: Does It Burn Calories?
Infectious DiseasesCold & Flu

Does a Fever Burn Calories?

Does a Fever Burn Calories?
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Updated on January 16, 2026
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Fever is your body's way of fighting infection. To make your body temperature go up, your metabolism goes into overdrive, which requires calories.

 If you’re carefully managing your calorie input or output, you might be concerned about how much more you may need to consume so that you get enough calories with a fever.
While a fever does burn calories and increase metabolism, the exact number of calories burned depends on your basal metabolic rate (BMR), which is determined by factors like muscle mass and age.

Calories Burned Differs From Person to Person

The bigger your body, the more calories you burn.

Men tend to burn more calories than women because men tend to have more muscle. Similarly, older adults tend to burn fewer calories because they lose muscle over time.

When people have a fever, “they may start shivering for the purpose of rapidly increasing the production of heat by the muscles,” Vargas says. “When this occurs, they can expect further increments in energy consumption.”

Feed Your Fever

Fevers use up calories, and all of those energy needs mean nutrition needs. If you have a fever, drink plenty of fluids to avoid dehydration and eat foods that are easy to digest. Try chicken soup for calories and fluid replacement, and to help keep mucus loose and draining.

What Is a Fever?

While a fever can make you feel sweaty and uncomfortable, it’s actually your body's way of trying to kill invading viruses or bacteria.

 These invaders do not survive as well at higher body temperatures, so your body raises your temperature to fight them. Fever also triggers your immune system to take action.

The average normal body temperature is about 98.6 degrees F. A fever is present when your body temperature is at 100.4 degrees F or higher.

 When your body's defense system detects a foreign invader like a virus, an area of your brain called the hypothalamus is alerted to raise your body temperature, like turning up the thermostat in your home.

That increase in the thermostat requires energy from your body's furnace, called your metabolism, says Oscar Morey Vargas, MD, an endocrinologist at Cleveland Clinic. “Body temperature has an effect on the number of calories you burn,” Dr. Vargas says. “Fever, for example, has links to higher metabolic requirements.” So when you have a fever, your body is working harder.

Metabolism and Fever

Your metabolism is the process your body uses to convert the calories you eat or drink into energy. Oxygen combines with these calories to release energy.

But your metabolism is unique to you — it's based on your BMR, which is the energy your body needs to carry out basic functions.

 The required calorie intake depends on many factors, and everybody's BMR is different. These factors affect your BMR:

  • Genes
  • Sex assigned at birth
  • Age
  • Body composition and size
  • Diet
  • Activity level

The Takeaway

  • A fever burns calories because your metabolism increases to raise your body temperature.
  • How many calories a fever burns depends on your BMR, which varies from person to person.
  • It’s important to stay hydrated and replenish extra calories burned by fever.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. True or False: Feed a Cold, Starve a Fever? North Shore Health System. January 31, 2020.
  2. Metabolism and Weight Loss: How You Burn Calories. Mayo Clinic. October 8, 2022.
  3. Fever in Adults: When to Worry. Harvard Health Publishing.
  4. Fever. MedlinePlus. July 27, 2025.
  5. Fever. Mayo Clinic. May 7, 2022.
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Sandy Bassin, MD

Medical Reviewer
Member of American College of Lifestyle Medicine

Sandy Bassin, MD, is an endocrinology fellow at Mount Sinai in New York City. She is passionate about incorporating lifestyle medicine and plant-based nutrition into endocrinology,...

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Chris Iliades

Chris Iliades, MD

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Chris Iliades, MD, is a full-time medical writer and journalist based in Boothbay Harbor, Maine. He practiced clinical medicine for 15 years before transitioning to medical writing...

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