How Many Calories Does a Fever Burn?

How Many Calories Does a Fever Burn?

How Many Calories Does a Fever Burn?
Adobe Stock
By
Updated on July 31, 2025
by
Fever is your body's way of fighting infection. To make your body temperature go up, your metabolism goes into overdrive, which requires calories.

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.

What Is a Fever?

You might think that having a fever is bad, but 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 burned," Dr. Vargas says. "Fever, for example, is associated with 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 make energy from the calories you eat or drink. 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.

 How many calories that requires depends on many factors, and everybody's BMR is different. Your BMR is affected by these factors:

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

Calories Burned Differs From Person to Person

The bigger your body, the more calories you burn.

People assigned male at birth tend to burn more calories than people assigned female at birth because people people assigned male at birth 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, further increments in energy consumption are expected."

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.

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.
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. MedlinePlus. July 27, 2025.
  4. Fever in Adults: When to Worry. Harvard Health Publishing.
  5. Fever. Mayo Clinic. May 7, 2022.
Meet Our Experts
See Our Editorial PolicyMeet Our Health Expert Network
Michelle-Seguin-bio

Michelle Seguin, MD

Medical Reviewer
Member of American College of Lifestyle Medicine

Michelle Seguin, MD, is a board-certified family medicine, lifestyle medicine, and certified functional medicine physician (IFMCP). She is a practicing physician at Root Functional Medicine, a leading telemedicine practice specializing in personalized, root-cause care.

See full bio
Chris Iliades

Chris Iliades, MD

Author

Chris Iliades, MD, is a full-time freelance writer based in Boothbay Harbor, Maine. His work appears regularly on many health and medicine websites including Clinical Advisor, Healthgrades, Bottom Line Health, HeathDay, and University Health News. Iliades also writes a regular blog for The Pulse, a website for fetal health and pregnancy.

Iliades is board-certified in Ear, Nose and Throat and Head and Neck Surgery. He practiced clinical medicine for 15 years and has also been a medical director for diagnostic research and a principal investigator for clinical research before he turned to full-time medical writing.

See full bio
See Our Editorial PolicyMeet Our Health Expert Network