How to calculate basal metabolic rate ? Definition and methods

We explain how to calculate your basal metabolic rate (BMR) using reliable equations such as the Harris-Benedict equation. You’ll also discover the factors that influence this calculation, including the total number of calories burned, how to integrate your level of physical activity, and tips for boosting your metabolism naturally to support overall health.

What is basal metabolic rate (BMR) ?

Basal metabolic rate (BMR), often abbreviated as MB or basal metabolism, represents the essential amount of energy your body requires to maintain its vital functions while resting. This includes fundamental processes such as breathing, blood pumping, digestion, and maintaining body temperature.Studies have shown the significance of BMR in overall health.

These resting energy requirements are the incompressible minimum needed to guarantee basal body function, even when you’re at rest, fasting for more than 12 hours, and in thermoneutral conditions. Understanding your BMR is crucial for maintaining health as you age.

Basal metabolic rate (BMR) is expressed in calories per day or watts, and varies according to several key factors, including weight, height, gender, muscle mass, and age. These equations reflect how the total amount of energy needed is based on these variables, explaining why basal energy needs differ from person to person.

Different calculation methods for men and women ?

Yes, methods for calculating basal metabolic rate take into account the physiological differences between men and women. For example, the Harris-Benedict formula, one of the most commonly used methods, proposes separate equations for the two sexes based on extensive studies conducted by scholars.

For men, the formula to calculate BMR in calories is as follows: 66 + (6.2 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years).

For women, the formula to calculate BMR in calories is: 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years).

To understand a woman’s basic metabolic rate, refer to our dedicated article.

These differences in formulas reflect physiological variations between the sexes, particularly in terms of body composition and metabolic rate. Men generally tend to have greater muscle mass than women, which influences their basal metabolic rate. Understanding these distinctions is essential for accurately calculating BMR using the appropriate equations and adapting nutritional intakes to support overall health.

Basal metabolic rate calculator (Black & al formula)

Basal metabolic rate meaning

How to calculate basal metabolic rate ?Different formulas

There are several formulas and equations for calculating basal metabolic rate, each supported by various studies and offering unique advantages and limitations. The choice of equation often depends on the person’s profile, lifestyle, and the level of precision required according to recent articles.

Harris and Benedict formula

The Harris and Benedict formula, proposed in the early 20th century, is one of the oldest and best-known formulas for estimating basal metabolic rate. The equations are as follows:

Men: MB = 66 + (13.7 × weight in kg) + (5 × height in cm) – (6.8 × age in years)

Women: MB = 655 + (9.6 × weight in kg) + (1.8 × height in cm) – (4.7 × age in years)

Although still in use, this formula is less precise for certain populations, notably the overweight and elderly.

Mifflin-St Jeor formula

Developed in 1990, the Mifflin-St Jeor formula is widely regarded as one of the most reliable and scientifically validated. It is recommended for the general population. The equations are as follows:

Men: MB = 10 × weight in kg + (6.25 × height in cm) – (5 × age in years) + 5

Women: MB = 10 × weight in kg + (6.25 × height in cm) – (5 × age in years) – 161

Black & al. formula

Proposed in 1996, the Black et al. formula offers greater precision for specific populations, notably the overweight and elderly. However, it is more complex to use. The equations are as follows:

Men: MB = 1.083 × weight in kg0^.48 × height in m0^.50 × age-0^.13

Women: MB = 0.963 × weight in kg0^.48 × height in m0^.50 × age-0^.13

In short, the choice of formula depends on your profile and your specific needs. The Mifflin-St Jeor formula is generally recommended for the general population, while the Black et al. formula is more appropriate for overweight or elderly people.

Calculate your basal metabolic rate

To calculate your basal metabolic rate accurately, we use the Black et al. method, recognized as one of the most reliable. This method is particularly suitable for overweight and elderly people.

Data to be collected (weight, height, age, gender)

To perform the calculation, you need to gather the following information:

• Weight: your weight in kilograms (kg).
• Height: your height in meters (m).
• Age: your age in years.
• Gender: male or female, as equations differ according to gender.

How do i calculate basal metabolic rate ?

Let’s say we wanted to calculate the basal metabolic rate of a 35-year-old man, 1.75 m tall and weighing 75 kg. Here are the steps:

For men, the Black et al. equation is as follows:

MB = 1.083 × P0^.48 × T0^.50 × A-0^.13

Where:

• P: weight in kg.
• T: height in meters.
• A: age in years.

By inserting the values :

MB = 1.083 × (75)^0.48 × (1.75)^0.50 × (35)^-0.13

After calculations, we obtain approximately :

MB ≈ 1,918 kcal/day

For a 30-year-old woman, measuring 1.60 m and weighing 60 kg, the equation would be :

MB = 0.963 × P0^.48 × T0^.50 × A-0^.13

By inserting the values :

MB = 0.963 × (60)^0.48 × (1.60)^0.50 × (30)^-0.13

After calculations, we obtain approximately :

MB ≈ 1,542 kcal/day

Interpreting the result

Basal metabolic rate is the amount of energy your body needs to maintain its vital functions at rest. For example, if the result for a man is around 1,918 kcal/day, this means that his body consumes this energy daily without any physical activity.

This data is essential for adjusting your nutritional intake and defining your health goals. It plays a key role in weight management and planning your total energy expenditure.

Factors influencing basal metabolic rate

The formulas for calculating basal metabolic rate (BMR) provide a useful estimate, but it’s essential to understand that it can vary considerably based on a number of factors, including health and body composition. For a more accurate assessment and personalized recommendations, supported by recent studies, we strongly advise you to consult a healthcare professional or nutritionist.

Here are the main factors that influence basal metabolic rate (BMR), affecting your body and overall health:

Age

Aging plays a major role in variations in basal metabolic rate. As we age, basal metabolic rate (BMR) tends to decrease, mainly due to the loss of muscle mass and the increase in body fat, which affects the number of calories burned.

Generally speaking, older people have a lower basal metabolic rate (BMR) than younger adults, which can influence their health and energy calories burned.

Gender

Gender is also a determining factor. Men generally have a higher basal metabolic rate (BMR) than women, largely due to their greater muscle mass and body composition. Muscle, being metabolically active tissue, consumes more calories than fat, affecting the BMR equations.

Size and weight

Size and weight have a direct influence on basic metabolism (BMR). The bigger and heavier a person is, the more calories their body requires to maintain its vital functions. However, it’s important to distinguish between fat mass and muscle mass, as muscles consume much more energy and calories than fat, impacting the BMR equations.

Body Composition

Body composition, particularly the percentage of fat and muscle mass, has a considerable impact on basal metabolic rate (BMR). Muscle expends around 20-25% of BMR in calories at rest, while fat consumes much less energy. Increasing muscle mass can therefore be an effective strategy for boosting BMR and enhancing overall health.

Physical activity

Regular physical activity, including prolonged exercise, plays an essential role in maintaining and even increasing basal metabolic rate (BMR). Engaging in regular exercise leads to an increase in muscle catabolism, which boosts BMR and the number of calories burned during the recovery phase, promoting better health.

What’s more, physical activity helps prevent muscle catabolism often associated with restrictive diets. By maintaining optimal muscle mass, regular exercise supports a higher BMR equation and contributes to overall health.

Genetic and environmental factors

Basic metabolism (BMR) is also influenced by genetic and environmental factors, such as climate or lifestyle habits. For example, a lack of sleep can slow down your metabolism, while extreme weather conditions can increase your energy expenditure in calories to maintain an adequate body temperature. These relationships are supported by studies available on PubMed.

By taking these elements into account, including your body composition and genetic factors, you can better understand why your basal metabolic rate (BMR) in calories may vary from that of another person, even if you apply the same calculation formulas and equations.

From basal metabolic rate to total energy expenditure

Calculating your basal metabolic rate is an essential step, but to better understand your overall energy needs, it’s just as important to consider your level of physical activity. This will enable you to determine your daily energy expenditure (DEJ).

Understand the concept of physical activity level (PAL)

Physical activity level (PAL) is a key element in estimating total energy expenditure. It represents the intensity and duration of your daily physical activity.

NAP is generally expressed as a physical activity factor, which varies according to the type and intensity of activities performed. For example, a sedentary person will have a low NAP, while a professional athlete will have a high NAP.

Here are the most common NAP categories:

• Sedentary: Little or no physical activity.
• Slightly active: Light physical activity (1 to 3 days a week).
• Moderately active: Moderate physical activity (3 to 5 days a week).
• Very active: Intense physical activity (6 to 7 days a week).
• Extremely active: Very intense physical activity (more than 7 days a week) or heavy physical work.

Calculate your daily energy expenditure (DEJ)

To determine your daily energy expenditure, add the energy consumed during physical activity to your basal metabolic rate. Here’s how to do it:

1. Calculation of basal metabolic rate: Use one of the formulas mentioned above to obtain your basal metabolic rate.
2. Determining the NAP: Evaluate your level of physical activity and assign it an appropriate multiplication factor.
3. Calculating energy expenditure linked to physical activity: Use the METs(Metabolic Equivalent of Task) method to estimate the energy expended during each activity.

The formula used is as follows:

Energy expenditure (kcal) = MET × weight (kg) × time (hours)

For example, for a 1-hour weight training session with a MET of 6 for a 75 kg man:

6 METs × 75 kg × 1 hour = 450 kcal

4. Calculating DEJ: Multiply your basal metabolic rate by the NAP factor, then add the estimated energy expenditure for each physical activity.

The final formula is :

DEJ = MB × NAP + Energy expenditure due to physical activity

This method offers a more precise approach to tailoring your nutritional planning to your specific needs, especially if you engage in regular or intensive physical activity.

How to increase basal metabolic rate naturally ?

Boosting your basal metabolic rate (BMR) naturally is not only possible but also beneficial to your overall health and the number of calories you burn daily. Discover proven methods to speed up your metabolism through healthy food, regular exercise, and lifestyle changes without resorting to chemicals or questionable supplements.

Adapted Food and Nutritional Rebalancing

Diet plays an important role in stimulating metabolism. Here are a few dietary principles to follow:

• Lean proteins: Include lean proteins such as chicken, fish, eggs, beans and legumes in all your meals. Proteins require more energy to metabolize than carbohydrates or fats, which helps increase basal metabolic rate.
• Complex carbohydrates: Choose fiber-rich complex carbohydrates such as sweet potatoes, brown rice, spelt or oats. These foods require more energy to digest, thus activating the metabolism.
• Good Lipids: Eat the good lipids found in avocados, oily fish, dried fruit and oils such as sesame and sunflower. These fats are essential for optimal body function and metabolism.

Hydration and Meal Frequency

Proper hydration and meal frequency are also important:

• Hydration: Drink at least 1 liter of water a day, mainly between meals. Good hydration can increase basal metabolic rate by 3%, while improving digestion and nutrient absorption.
• Meal frequency: Eat 5 small meals a day instead of 2 or 3. This strategy helps maintain an active metabolism throughout the day.

Targeted Physical Activity

Physical activity is a powerful metabolic gas pedal:

• Bodybuilding: Bodybuilding exercises are particularly effective because muscles consume more energy than fat. Even short sessions of 15-20 minutes a day can burn calories at rest and speed up metabolism.
• HIIT cardio: High-intensity interval cardio (HIIT) activities are also highly effective in boosting metabolism. These sessions can increase metabolism by over 40% in the 72 hours following exercise.
• Regular activity: Regular physical activity such as walking, jogging or cycling also helps to increase energy expenditure and maintain an active metabolism.

Sleep and Stress Management

Sleep and stress management are essential for an optimal metabolism:

• Sleep: Quality sleep is essential for the body to regenerate and maintain an active metabolism. Lack of sleep can slow down the metabolism.

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• Stress management: Stress management is important because chronic stress can negatively affect metabolism. Practicing relaxation activities such as meditation or yoga can help reduce stress and maintain a healthy metabolism.

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By incorporating these natural methods into your daily routine, you can significantly boost your basal metabolic rate and improve your overall health.

What you need to know about calculating basal metabolic rate

Understanding and calculating your basal metabolic rate is an essential step towards optimal health and weight management. The Harris-Benedict, Mifflin-St Jeor, and Black & al. formulas are valuable tools for estimating your basic energy needs. To obtain an accurate estimate, it’s important to take into account factors such as age, gender, height, weight and body composition.

By adopting a balanced diet, rich in proteins, complex carbohydrates and healthy fats, together with regular physical activity, you can significantly improve your basal metabolic rate. Stress and sleep management also play a key role in this process. Don’t forget to take into account your level of physical activity when calculating your daily energy expenditure and adjust your nutritional intake accordingly.

It’s time to take action! Calculate your basal metabolic rate, adopt healthy habits, and consult a healthcare professional for personalized advice. A more balanced life and better health are within reach.

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FAQ

What factors influence an individual’s basal metabolic rate?

An individual’s basal metabolic rate is influenced by a number of factors, including age, height, weight and gender, as well as genetic factors and body composition, particularly muscle mass. Climate and facultative thermogenesis can also play an important role.

How does basal metabolic rate differ between men and women?

Basic metabolism differs between men and women in several key aspects:

• Women burn more carbohydrates and less fat at rest than men.
• Men generally have a higher body mass, which translates into a higher basal metabolic rate, requiring more calories for basic functioning.
• Sex hormones, particularly estrogen, influence women’s ability to burn calories and store fat.

What proportion of daily energy expenditure does the basal metabolic rate represent ?

Basic metabolism accounts for between 60% and 70% of daily energy expenditure. This proportion varies according to the individual’s level of physical activity, ranging from 45% for very active people to 70% for sedentary individuals.

Why is knowing your basal metabolic rate important for weight management and overall health ?

Knowing your basal metabolic rate is essential for weight management and overall health. It indicates the minimum amount of energy required for the body to function at rest. By understanding this energy requirement, it is possible to adapt calorie intake and physical activity to :

• Optimize calorie combustion.
• Prevent loss of muscle mass.
• Maintain a healthy energy balance.

A precise understanding enables personalized diet and exercise strategies to be put in place, promoting sustainable weight loss and better overall health.