Weight Loss

You Can Boost Weight Loss by Knowing Your BMR: Here’s How It Works

You Can Boost Weight Loss by Knowing Your BMR: Here’s How It Works
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Updated on January 31, 2025
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The minimum number of calories you need for your body to function is called your basal metabolic rate, or BMR. You burn most of your daily calories with zero effort, movement, or even thinking. Whether you’re sleeping, talking on the phone, working at a keyboard, or simply watching TV, your body is burning calories to keep your organs working — your heart pumping and your lungs breathing. If you know your BMR, you can better determine your caloric needs for healthy weight loss.

What Is Basal Metabolic Rate?

The number of calories used to maintain basic bodily functions add up to your BMR. “Basal” essentially means “base.” Think of it as the amount of energy (aka number of calories) that is just enough to cover all your body’s bases.

BMR is one of many factors in the total number of calories you burn in a given day, also called your total daily energy expenditure (TDEE). Your base metabolism accounts for roughly 60 to 75 percent of your TDEE.

TDEE is determined by genetics, biological sex, age, body size, and lean body mass. Hormonal health can also affect metabolism.

While many people blame a slow metabolism (they mean BMR) on weight gain, it’s actually true that larger body sizes have higher BMR, explains Tim Church, MD, PhD, the chief medical officer at Wondr Health, a company that provides digital health and weight loss programs.

The majority of differences between any two people’s basal metabolic rate comes down to fat mass and free-fat mass, which includes organ size and muscle levels, according to Herman Pontzer, a professor of evolutionary anthropology at Duke University in an article for Scientific American.

 Age is also a factor, he says.

At rest, a pound of fat burns roughly two calories per day and a pound of muscle burns roughly six calories, Dr. Church says.

That’s why men naturally enjoy a higher BMR than women, as they tend to have more overall body size and lean mass levels, explains Sari Greaves, RDN, a registered dietitian-nutritionist at LBS Nutrition in East Brunswick, New Jersey, and the author of Cooking Well Healthy Kids: Easy Meals for Happy Toddlers.

Basal Metabolic Rate (BMR) vs. Resting Metabolic Rate (RMR)

BMR is often used interchangeably with resting metabolic rate, or RMR, but they’re actually slightly different.

“BMR is the absolute minimum metabolic rate,” Church says. It is typically determined only in laboratory settings, with people undergoing measurements in a darkened, temperature-controlled room immediately after 8 hours of sleep and 12 hours of fasting and reclining.

Meanwhile, “RMR is the metabolic rate when at rest, awake, and sitting still.” RMR testing does not require a fast and may be performed later in the day. RMR is typically 10 to 20 percent higher than BMR.

How to Estimate Your BMR or RMR to Help With Weight Loss

Knowing your BMR or RMR can help you better determine your total daily energy expenditure in order to create a caloric deficit, defined as consuming fewer calories each day than you burn for energy. A caloric deficit is required to lose weight.

But because most people do not have access to state-of-the-art labs to determine BMR exactly, equations are often used to make approximations. The easiest way to measure your metabolic rate is to use an online calculator. You can find many calculators online, and all use varying equations.

Revised Harris-Benedict Equation

The commonly used metabolic equation, called the Harris and Benedict equation, was first designed in 1918 (and updated in 1984). While it was intended to estimate BMR, it actually estimates RMR, according to the National Academy of Sports Medicine.

 It uses height, weight, biological sex, and age to determine RMR and is based on average lean mass levels.

Below are examples of how to calculate your RMR using the revised Harris and Benedict equation.

Men: (88.40 + 13.40 x weight in kilograms [kg]) + (4.80 x height in centimeters [cm]) – (5.68 x age in years)

For example, if a man is 180 pounds, 5'11", and 43, his RMR is 1,804 calories.

Women: (447.60 + 9.25 x weight in kg) + (3.10 x height in cm) – (4.33 x age)

For example, if a female is 130 pounds, 5'3", and 36, her RMR is 1,333 calories.

Mifflin-St Jeor Equation

The Mifflin-St Jeor equation is another equation that uses the same variables but may be more accurate, Church says.

Here’s what the Mifflin-St Jeor equation looks like for men and women:

Men: (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age in years) + 5

For example, if a male is 180 pounds, 5'11", and 43, his RMR is 1,734 calories.

Women: (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age in years) – 161

For example, if a female is 130 pounds, 5'3", and 36, her RMR is 1,249 calories.

Cunningham Equation

Other metabolic equations, such the Cunningham equation, use your total level of lean body mass, which is a primary determiner of BMR and therefore RMR. But calculation requires you to measure your body’s levels of fat versus free-fat mass, Church says. Calipers and smart scales are two popular at-home options, but the most accurate measures are performed in professional and laboratory settings.

Here are examples of how to calculate your RMR using the Cunningham equation:

Men and women: 500 + (22 x lean body mass in kg)

For example, if a man is 170 pounds, 5'11", 43, and his body-fat percentage is 20 percent, his RMR is 1,857 calories.

If a female is 130 pounds, 5'3", 36, and her body-fat percentage is 25 percent, her RMR is 1,473 calories.

How to Calculate Your BMR and Total Daily Energy Expenditure

BMR or RMR can be used to estimate total daily caloric expenditure. According to the American Council on Exercise, after you determine your RMR using one of the above equations or an online calculator, you can multiply it by one of the numbers below, called activity factors.

  • Sedentary Little to no exercise, multiply by 1.2
  • Lightly Active Light exercise one to three days per week, multiply by 1.375
  • Moderately Active Moderate exercise on three to five days per week, multiply by 1.55
  • Very Active Hard exercise six or seven days per week, multiply by 1.725
  • Extremely Active Hard exercise every day and/or a physical job, multiply by 1.9

If the man in the above example exercises two days per week, his daily caloric expenditure is roughly 2,384 to 2,481 calories.

If the woman in the above example exercises six days per week, her daily caloric energy expenditure is roughly 2,155 to 2,541 calories.

This calculation gives you the estimated number of calories you burn in one day at your current level of activity; this is how many calories you need to consume per day to stay at your current weight.

How Knowing Your BMR Can Help You Lose Weight

To lose weight, you need a caloric deficit, meaning that you must either reduce your caloric intake below your total daily energy expenditure or increase your total daily energy expenditure, says Greaves. For example, you can try multiplying your RMR by various activity factors to see how your daily caloric burn would fluctuate with increased exercise.

Another benefit of increased exercise is that it can have a small effect on both RMR and BMR. One meta-analysis showed that resistance exercise provides a temporary boost to your RMR, an effect sometimes referred to as afterburn, or excess post-exercise oxygen consumption (EPOC).

 This represents the calories that the body expends to return the body to homeostasis, or your normal temperature, blood pressure, oxygen, and other bodily systems, after exercise.

Strength training provides a more lasting boost to BMR by altering your body’s composition. As previously stated, a pound of fat burns roughly two calories per day while a pound of muscle burns six at rest, Church says. To put that into perspective, gaining two pounds of muscle will increase RMR by about 12 calories.

The Takeaway

  • Your basal metabolic rate is how many calories your body needs at rest in order to function properly.
  • Calculating your BMR and RMR helps you determine an effective caloric intake for weight loss.
  • Use trusted online calculators to estimate your BMR and adjust your diet or activity levels according to those estimates.

Additional reporting by Dennis Thompson Jr.

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Reyna Franco, RDN

Medical Reviewer

Reyna Franco, RDN, is a New York City–based dietitian-nutritionist, certified specialist in sports dietetics, and certified personal trainer. She is a diplomate of the American College of Lifestyle Medicine and has a master's degree in nutrition and exercise physiology from Columbia University.

In her private practice, she provides medical nutrition therapy for weight management, sports nutrition, diabetes, cardiac disease, renal disease, gastrointestinal disorders, cancer, food allergies, eating disorders, and childhood nutrition. To serve her diverse patients, she demonstrates cultural sensitivity and knowledge of customary food practices. She applies the tenets of lifestyle medicine to reduce the risk of chronic disease and improve health outcomes for her patients.

Franco is also a corporate wellness consultant who conducts wellness counseling and seminars for organizations of every size. She taught sports nutrition to medical students at the Albert Einstein College of Medicine, taught life cycle nutrition and nutrition counseling to undergraduate students at LaGuardia Community College, and precepts nutrition students and interns. She created the sports nutrition rotation for the New York Distance Dietetic Internship program.

She is the chair of the American College of Lifestyle Medicine's Registered Dietitian-Nutritionist Member Interest Group. She is also the treasurer and secretary of the New York State Academy of Nutrition and Dietetics, having previously served in many other leadership roles for the organization, including as past president, awards committee chair, and grant committee chair, among others. She is active in the local Greater New York Dietetic Association and Long Island Academy of Nutrition and Dietetics, too.

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K. Aleisha Fetters is a Chicago-based fitness writer and certified strength and conditioning specialist who empowers others to reach their goals using a science-based approach to fitness, nutrition and health. Her work has been featured in various publications including Time, Men's Health, Women’s Health, Runner’s World, Self, O, U.S. News & World Report, and Family Circle.  She also creates editorial content and programming for Exos, a sports performance company.

Fetters earned both her bachelor’s and master’s degrees in journalism from the Medill School of Journalism at Northwestern University. She has written multiple books -- Give Yourself MORE, Fitness Hacks for Over 50, My Pocket Guide to Stretching -- and coauthored The Woman’s Guide To Strength Training. She is regularly interviewed as an expert on strength training, women's fitness, and mindset. She works with trainees in person and online.

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Resources
  1. Comana F. Resting Metabolic Rate: How to Calculate and Improve Yours. National Academy of Sports Medicine.
  2. Pontzer H. New Human Metabolism Research Upends Conventional Wisdom About How We Burn Calories. Scientific American. January 1, 2023.
  3. Merritt A. BMR Versus RMR. American Council on Exercise.
  4. Kelly M. Resting Metabolic Rate: Best Ways to Measure It — and Raise It, Too. American Council on Exercise.
  5. MacKenzie-Shalders K et al. The effect of exercise interventions on resting metabolic rate: A systematic review and meta-analysis. Journal of Sports Sciences. May 12, 2020.
  6. What Is EPOC? (And Why It Matters). Cleveland Clinic. October 23, 2023.