Basal Metabolism Calculator

How to Use the Basal Metabolic Rate Calculator

To use this simulator, you simply have to enter the data requested in the different cells, namely: your sex, your weight in kg, your height, your age, and your activity level.

Once you have entered all this data, click on “Calculate” and our online simulator will do the rest, giving you the number of calories you consume daily in a quick and clear manner.

What is the Basal Metabolic Rate?

There is much talk or writing about metabolism, but it is rarely defined what it is.

Metabolism is the set of chemical processes that occur within the body's cells. The most relevant process is the transformation of the nutrients contained in food into energy that can be used by the body. (1)

Knowing your metabolism will help you have better control over the number of calories you consume daily.

The Basal Metabolic Rate is the minimum amount of energy required by a person for their body to perform vital functions.

The basal metabolism provides energy to the brain, heart, lungs, kidneys, and other organs of the body that work 24 hours a day. (2)

It accounts for 60 to 70% of the daily energy expenditure of most sedentary adults or those with light physical activity. The case is different for physically very active individuals, which is approximately 50%.

This Rate can vary depending on body composition, since muscle mass is metabolically more active than body fat. (2)

The term Basal Metabolism was coined by Margus-Levy in 1899 and established a series of conditions for its measurement.

• The subject had to be at rest before and during the measurement, lying down, but awake.
• Be fasting for 10-12 hours.
• Exposed to a controlled ambient temperature (22-26 ºC).
• Free from emotional stress and infections. (3)

Basal metabolism, expressed as BMR, is different from the resting metabolic rate (RMR) or Resting Energy Expenditure (REE).

The latter does not require the person to be fasting, therefore, it accounts for the energy used to biologically process food.

Calculating BMR with the Harris-Benedict Formula

There are many formulas and equations that allow us to calculate your basal metabolic rate, also expressed through the acronyms BMR or TMB.

The Harris-Benedict formula is perhaps the most widely used equation to determine the BMR.

It was first published in 1919, these authors conducted a series of research based on measurements of the BMR of 136 men and 103 women at the Carnegie Nutrition Laboratory in Boston; rigorous statistical methods were used to ensure that the created equation fulfilled its function. (3)

This formula takes into consideration different characteristics of a person: level of physical activity, whether male or female, as well as height, weight, and age.

In most calculators, a simplified version is used, but, in our case, we have decided to use the exact version with all the decimals, to obtain a more precise calculation.

The equation for women is as follows:

• BMR = 655.0955 + (9.5634 * weight in kg) + (1.8449 * height in cm) - (4.6756 * age in years)

The equation for men is:

• BMR = 66.473 + (13.7516 * weight in kilograms) +(5.0033 * height in centimeters) - (6.755 * age in years)

How to Calculate Caloric Expenditure from Basal Metabolism

Let's take an example, imagine that your intention is to maintain your body weight stable, the energy used in certain daily activities should be equal to that you consume in your diet.

Weight loss will occur at the moment when the energy intake is lower than the energy consumed, while your body weight will increase if the perceived calories are higher than the energy used.

It is essential to know the amount of calories required each day to achieve the energy balance necessary to reach a balanced weight and lifestyle that can satisfy you. How do you know it? By calculating the daily caloric expenditure.

To obtain the daily caloric expenditure, the basal metabolism should be multiplied by the constants that correspond to your physical activity, classified by level of intensity.

The factors related to daily physical activity are equivalent to 1.2 if you are a person who is close to sedentary, however, it will be 1.3 if you perform some type of physical activity and 1.4 if, on the contrary, you perform an intense physical activity.

Attention: The information provided in this article cannot replace the instructions given by your nutritionist. Moreover, if you take your physical goals seriously, we recommend you to consult a nutrition specialist who can design for you a personalized plan more suitable to your personal characteristics.

Now you know everything you need to know about calculating the basal metabolic rate: you have learned to use the Harris-Benedict formula whether you are a man or a woman, as well as some useful tips on its application in different contexts.

If you liked our basal metabolism calculator, we encourage you to share it with your contacts on your social networks, thus helping us to build a better community of calculators.

As always, if you find any problem in using this calculator or any other, want to suggest a new one or simply want to thank us for our work, you can freely use the contact section.

Bibliographic Resources

• Michael C. Latham. Human Nutrition in the Developing World. Part II: Basic Nutrition. Chapter 8. Body composition, food functions, metabolism, and energy. FAO Food and Nutrition Series No. 29. 2002. Available at: http://www.fao.org/docrep/006/w0073s/w0073s0c.htm
• Blasco, R. Resting energy expenditure. Evaluation methods and applications. Rev. Esp. Nutr. Comunitaria 2015;21(Supl. 1):243-251 Available at: http://www.renc.es/imagenes/auxiliar/files/RENC2015supl1GER.pdf
• Melier Vargas Z et al. Resting energy expenditure and body composition in adults. Fac. Med., Volume 59, Number 1, p. 43-58, 2011. Available at: https://revistas.unal.edu.co/index.php/revfacmed/article/view/24108/38990

BS Raquel Mendoza Hernández

Bachelor's degree in Nutrition and Dietetics from UCV. Postgraduate diploma in Public Management in Nutrition from UBV.

Raquel Mendoza Hernández holds a degree in Nutrition and Dietetics from the Central ... Read more »