How to Calculate Basal Metabolic Rate: Why it Matters?

Introduction

Your body consumes calories in three different ways, one of which is your basal metabolic rate (BMR). It’s the quantity of calories required for basic bodily functions. Your BMR is influenced by a number of factors, and each person’s rate varies. You may calculate your BMR using specific formulas according to your age, height, weight, and sex.

Basal Metabolic Rate (BMR): What Is It?

The minimum calories your body requires to function at a basic level is known as your basal metabolic rate (BMR). This involves preserving all of your cells as well as vital physiological processes like breathing, blood flow, and body temperature. Individual differences in BMR are caused by several factors.

The primary energy expenditure source in your body is your BMR. It provides between 60 and 70 percent of the energy your body needs. About 10% of your body’s total energy is used to convert food into fuel. Your physical movement is powered by the residual energy.

Genetics, biological sex, age, physical size, and lean body mass all affect TDEE. Metabolism can also be impacted by hormonal health.

How BMR is determined

Direct calorimetry, indirect calorimetry, or a simple mathematical formula can all be used to determine your BMR.

You should go to a clinic that provides direct or indirect calorimetry if you want the most precise figure:

The most precise technique is direct calorimetry. It entails spending time with minimal to no movement in a calorimeter, a strictly regulated space. However, it is hard to get and is exclusively utilized in research settings.
An in-office tool that detects your body’s exchange of carbon dioxide and oxygen is used in indirect calorimetry.
However, researchers have created more practical ways to calculate BMR because the majority of individuals do not have access to these instruments. Specifically, the Mifflin-St. Jeor’s equation is a widely used method for rapidly generating it.

In technical terms, this formula determines your resting metabolic rate (RMR), which differs somewhat from BMR. RMR calculates how many calories you burn when you’re at rest and moving very little. BMR counts calories with no movement during the day and is more restricted.

How to Calculate Your RMR or BMR to Aid in Losing Weight

To generate a caloric deficit, which is defined as ingesting fewer calories daily than you burn for energy, knowing your BMR or RMR can help you better calculate your total daily energy expenditure. Losing weight requires a calorie deficit.

However, equations are frequently used to make assumptions because most people lack access to cutting-edge labs to determine BMR precisely. Using an online calculator is the simplest approach to determining your metabolic rate. Numerous calculators are available online, and they all employ different equations.

Updated Harris-Benedict Formula

The Harris and Benedict equation, a widely used metabolic formula, was initially created in 1918 and revised in 1984. The National Academy of Sports Medicine claims that although it was designed to assess BMR, it actually estimates RMR. RMR is based on average lean mass levels and is calculated using height, weight, age, and biological sex.
Here are some examples of how to use the updated Harris and Benedict equation to determine your RMR.

Men: (88.40 + 13.40 x kg weight) + (4.80 x cm height) – (5.68 x years of age)

For instance, the RMR of a male who weighs 180 pounds, is 5’11”, and is 43 years old is 1,804 calories.

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

For instance, a woman who weighs 130 pounds, is 5’3″, and is 36 years old has an RMR of 1,333 calories.

The Mifflin-St. Jeor Formula

Another equation that makes use of the same variables but might be more precise is the Mifflin-St Jeor equation.

The Mifflin-St Jeor equation for men and women looks like this:

Men: (10 x kg of weight) + (6.25 x cm of height) – (5 x years of age) + 5

For instance, a male who weighs 180 pounds, is 5’11”, and is 43 years old has an RMR of 1,734 calories.

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

For instance, the RMR of a female who weighs 130 pounds, is 5’3″, and is 36 years old is 1,249 calories.

The Cunningham Formula

Your entire level of lean body mass, which is a key factor in determining BMR and hence RMR, is used in other metabolic calculations, such as the Cunningham equation.  The evaluation necessitates measuring your body’s fat vs free-fat mass. Although smart scales and calipers are common at-home tools, professional and laboratory environments are where the most accurate measurements are taken.

Here are some examples of how to use the Cunningham equation to determine your RMR:

male and female: 500 + (22 x lean body mass in kg)

For instance, a man’s RMR is 1,857 calories if he weighs 170 pounds, is 5’11”, 43, and has a 20 percent body fat percentage.

A female’s RMR is 1,473 calories if she weighs 130 pounds, is 5’3″, and has a 25% body fat percentage.

Determining your basal metabolic demands is made simple by the numerous online BMR calculator applications. However, due to variables including age, gender, body composition, and ethnicity, the typical range of basal metabolic rate varies greatly between people.

The average daily BMR for adult men is between 1,500 and 1,800 kcal, while some people have values as low as 1,027 kcal and as high as 2,499 kcal.
A woman’s daily BMR typically ranges from 1,200 to 1,500 kcal, depending on her body size and other variables.

What elements influence the basal metabolic rate?

Your basal metabolic rate is influenced by several things, such as:

• Size of the body: Your body needs more energy to sustain more bodily tissue and cells.
• The quantity of muscle that is lean: To sustain itself, muscle tissue needs a lot of energy.
• Quantity of bodily fat, or adipose tissue: Although fat cells need less energy to sustain themselves than muscle tissue, they nonetheless need energy.
• Sex: Because they are typically larger than females, males typically have a faster BMR. Because they have higher levels of testosterone, men also typically have more lean muscle mass.
• Age: The primary cause of your declining BMR as you age is a loss of muscle mass. However, as you age, hormonal and neurological changes may also have an impact on your BMR.
• Race: Your BMR may be impacted by your race and/or ethnicity. This is still being investigated by researchers.
• Genetics: Your BMR is probably influenced by your genes. The impact of genetics on metabolism is still being investigated by researchers.

Your BMR may be impacted by the following transient circumstances:

• Hunger, fasting, or missing meals: Your body is constantly attempting to prevent weight loss because of evolution. Your body will slow down your BMR if you eat too few calories.
• Environmental temperature: Your body has to work harder to maintain a healthy body temperature if you’re in an extremely hot or cold environment (e.g., by shivering or sweating). Your BMR rises in these situations.
• Amounts of thyroid hormones: Your BMR rises when you have hyperthyroidism or elevated thyroid hormone levels. Your BMR is lowered by hypothyroidism, or low thyroid hormone levels.
• Disease or harm: Your body works harder to fight off an infection and/or repair damaged tissues while you’re ill or injured, which raises your BMR.
• Stimulants: Caffeine, nicotine, and amphetamines are examples of stimulants that can raise your BMR.

The following life phases have an impact on your BMR:

• Expansion: As they grow, infants and youngsters need more energy to actively produce tissue.
• Being pregnant: Due to an increase in body mass and the energy needed to produce a fetus, your BMR rises during pregnancy.
• Lactation: To produce breast milk, your body needs extra energy. According to studies, the energy required to produce milk increases by 15% to 25%.
• Menopause: Lean muscular mass decreases during menopause due to hormonal changes. Your BMR usually drops as a result.

The BMR calculator’s limitations

BMR calculators are helpful, but they are not entirely accurate. Despite being one of the most accurate calculators, the Mifflin-St. Jeor’s equation might yield results that are approximately 10% off from your actual BMR.

Additionally, you aren’t really figuring out how many calories you need each day if your activity level isn’t taken into account. It is neither safe nor healthy to consume just enough calories to meet your BMR.

Lastly, even while your BMR can give you some information, it doesn’t give you a complete picture of your health. Important aspects of health include factors such as your muscle-to-fat ratio, underlying medical conditions, hormone levels, and other indicators.

How Understanding Your BMR Can Aid in Weight Loss

To lose weight, you must either increase your daily energy expenditure or decrease your calorie intake below your total daily energy expenditure. To see how your daily calorie burn would change with increasing exercise, you could, for instance, try multiplying your RMR by different activity factors.

Increased activity can also have a minor impact on both RMR and BMR, which is another advantage. Resistance training temporarily increases your RMR; this phenomenon is sometimes called afterburn or excess post-exercise oxygen consumption (EPOC). This is the amount of energy used by the body to restore homeostasis, normal blood pressure, temperature, oxygen levels, and other physiological systems after physical activity.
By changing the composition of your body, strength exercise increases BMR over time. As mentioned earlier, a pound of muscle burns six calories while at rest, but a pound of fat burns about two. To put it into context, RMR will rise by roughly 12 calories if you gain two pounds of muscle.

How to Manage Your Weight with Your BMR

Effective weight management techniques are based on your basal metabolic rate:

• Determine the basic requirements: To calculate the minimal number of calories needed for basic health, use your BMR.
• Make sustainable deficits: Instead of drastic calorie limitations below BMR, aim for modest calorie reductions below TDEE.
• Maintain muscle mass: To retain muscular tissue that boosts metabolism, focus on strength training and consuming a sufficient amount of protein.
• Keep a proper eye on progress: When your body composition and weight change, recalculate your basal metabolic rate.
• Establish reasonable expectations: Knowing your BMR makes it easier to set realistic weight loss goals.
• Prevent metabolic harm: Eat less than your basal metabolic rate regularly without medical supervision.

Common Myths About BMR

There are several myths about basal metabolic rate that can hinder your health progress.

• Myth: Thin people always have faster metabolisms
• Reality: When calculating BMR, muscle mass and genetics are more important than total body size.
• Myth: You can significantly increase your basal metabolic rate with supplements
• Reality: Compared with lifestyle modifications, most metabolic supplements have negligible, transient effects.
• Myth: Starvation diets increase metabolism
• Reality: Your body saves energy when you severely restrict your caloric intake, which usually reduces your BMR.
• Myth: Throughout your life, your basal metabolic rate remains constant
• Reality: Although BMR naturally decreases with age, diet, and exercise can have an impact

Health Conditions That Affect BMR

Your basal metabolic rate is greatly affected by several medical conditions. Because hyperthyroidism speeds up metabolism, it frequently results in inexplicable weight loss, a fast heartbeat, and an increase in appetite. On the other hand, hypothyroidism slows down metabolism, which results in weariness, cold sensitivity, and weight gain.

When your body shifts its energy toward healing and recovery, acute illnesses like infections, burns, or trauma cause your basal metabolic rate to momentarily rise. Additionally, metabolic efficiency can be changed by chronic diseases like diabetes, some types of cancer, and autoimmune illnesses.

How Basal Metabolic Rate Changes With Age

Throughout maturity, your basal metabolic rate steadily decreases; beyond the age of 20, it usually decreases by 1% to 2% every ten years. Hormonal changes, a decline in physical activity, and increasing muscle mass loss are the main causes of this reduction.

Age-related BMR reduction is not unavoidable, though. Frequent aerobic activity promotes general metabolic health, whereas resistance training helps maintain muscle mass. The normal decline in basal metabolic rate can be considerably slowed by maintaining a sufficient protein diet and continuing physical activity.

What is the typical basal metabolic rate?

In terms of basal metabolic rates, there is no such thing as “normal.” Based on several variables, each person has a body mass index (BMI) that is specific to them. When it comes to BMR, scientists can only offer averages.

A male’s daily BMR is around 1,696 calories (7,100 kilojoules). A typical female’s daily BMR is approximately 1,410 calories (5,900 kilojoules). Depending on your race and/or ethnicity, these estimations can vary.

It’s crucial to keep in mind that this energy (calorie) expenditure just includes the energy your body needs to continue operating at its most basic level. The calories your body requires for physical activity and to convert food into energy are not included in these figures.

It’s recommended to speak with a trained dietitian or your healthcare provider if you have concerns about how many calories you should eat each day. They can assist you in determining a reasonable figure based on your particular situation.

How can you figure out your basal metabolic rate?

Measuring your BMR under extremely controlled settings in a lab setting yields the most precise results. To be more precise, a professional would determine your BMR when you’re:

• completely at rest.
• both physically and mentally at ease.
• 12 to 14 hours after your last meal, while you are awake following sleep.
• In an environment that is comfortably warm, that is, at a temperature that is equal to your body temperature.

Scientists have created formulas to estimate your BMR because the majority of individuals lack access to this type of testing. The Harris-Benedict equation is the one that is most frequently utilized.

How should your basal metabolic rate be raised?

You can’t do much to alter your BMR in many ways. Your height, age, and heredity are some of the variables that affect your BMR that you cannot change. Gaining lean muscle mass is a good approach to raising your BMR. Because lean muscular tissue needs a lot of energy to maintain its structure, this raises your BMR.

Lean muscle can be developed by regularly including strength-training and resistance-training activities in your regimen, which are distinct from aerobic activity. Kettlebell training, Pilates, and weightlifting are a few examples of this kind of exercise.

It’s not always a good thing to have a very quick metabolism (BMR). For instance, a major sickness such as cancer might cause a condition known as hypermetabolism. Additionally, certain stimulants and conditions like hyperthyroidism can speed up your metabolism, but they can also be detrimental to your health.

Contact your healthcare physician if you have any questions or concerns regarding your metabolism and how it impacts your weight and overall health

What does basal metabolic rate tell you?

The number of calories you burn while at rest is indicated by your BMR. Before taking into account your everyday movement, it serves as an indicator of your metabolic activity. But in reality, BMR is just the initial part of a bigger equation because we don’t utilize it to determine our daily caloric requirements.

You must include an activity element in the formula to determine your TDEE:

• 1.2: sedentary, meaning they don’t exercise much
• 1.375: moderately active (one to three days a week)
• 1.55: fairly active (six to seven days a week of moderate exercise)
• 1.725: extremely active (doing vigorous activity twice a day or daily)
• 1.9: extremely active (physical labor, intense training, or exercise)

After that, you can use this formula to determine your TDEE:

BMR x activity factor equals TDEE.
You can use this figure to get a ballpark estimate of how many calories your body requires each day to keep you at your present weight.

What does having a lower basal metabolic rate entail for your health compared to having a higher one?

A higher BMR may be a sign of extra muscular mass, a larger body, a genetic predisposition for a quicker metabolism, or even an underlying medical issue like hyperthyroidism. Being healthier or less healthy than someone else is not always indicated by a greater or lower BMR.

You might want to see a doctor to get checked for diseases like diabetes and thyroid problems that can impact metabolism if you’re still having trouble losing or gaining weight, even after making modifications to your eating habits and level of physical activity.

Is it possible to modify your basal metabolic rate?

Numerous factors determine your BMR, including:

• body size (weight and height), age, and sex
• hormones, genetics, and body composition (fat and muscular mass)
• health issues
• Some of the factors, like your body composition, are somewhat within your control, but others, like your age, height, and genetics, are beyond your control.

The bottom line

The approximate quantity of calories your body burns while you are not moving at all is known as your “basal metabolic rate,” or “BMR.”

You can quickly calculate your BMR using the Mifflin-St Jeor equation because you might not have access to a clinic that provides direct or indirect calorimetry.

However, bear in mind that this figure does not indicate the quantity of calories you must consume each day; to maintain your health, you must consume more. You must compute your BMR and multiply it by an activity factor to determine how many calories you require each day.

If you are unsure of how many calories you require, consider speaking with a physician or a qualified nutritionist about your energy needs.

If you want to raise your BMR, try to build muscle and make sure you’re getting enough calories each day. Your height, age, and heredity are among the variables that determine your BMR, though, and they are beyond your control.

FAQs

References

• Professional, C. C. M. (2025, September 8). BMR (Basal Metabolic Rate). Cleveland Clinic. https://my.clevelandclinic.org/health/body/basal-metabolic-rate-bmr
• Cpt, K. D. M. R. (2022, November 15). How to calculate your basal metabolic Rate. Healthline. https://www.healthline.com/health/how-to-calculate-your-basal-metabolic-rate#whats-a-healthy-bmr
• Fetters, K. A. (2025, January 31). You can boost weight loss by knowing your BMR: Here’s how it works. EverydayHealth.com. https://www.everydayhealth.com/weight/boost-weight-loss-by-knowing-your-bmr.aspx