Calculate Your Basal Metabolic Rate (BMR)

Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 2009/03/31 - Updated: 2024/09/26
Publication Type: Conversion, Calculation
Topic: Medical Calculators and Charts - Publications List

Page Content: Synopsis - Introduction - Main

Synopsis: Basal Metabolic Rate calculator shows the number of calories you burn when at rest in bed or resting metabolic rate RMR.

Why it matters: A Basal Metabolic Rate (BMR) calculator is a valuable tool for understanding your body's basic energy needs. It calculates the number of calories your body burns while at complete rest, which accounts for up to 70% of your total daily calorie expenditure. This information is crucial for anyone looking to manage their weight, plan their diet, or improve their overall health. By knowing your BMR, you can make more informed decisions about your calorie intake and create a more effective nutrition and exercise plan tailored to your body's specific needs. The calculator provides a personalized estimate, taking into account factors like age, gender, height, and weight, making it a useful starting point for individuals aiming to achieve their health and fitness goals. - Disabled World (DW).

Introduction

Basal Metabolic Rate (BMR) is the minimum calorific requirement needed to sustain life in a resting individual, or the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans).

Main Item

Basal Metabolic Rate is defined as the minimal rate of energy expenditure per unit time by warm-blooded animals at rest. It is reported in energy units per unit time ranging from watt (Joule/second) to ml O2/min or Joule per hour per kg body mass J/(h.kg)). Proper measurement requires a strict set of criteria be met. These criteria include being in a physically and psychologically undisturbed state, in a thermally neutral environment, while in the post-absorptive state (i.e., not actively digesting food).

In bradymetabolic animals, such as fish and reptiles, the equivalent term Standard metabolic rate (SMR) is used. It follows the same criteria as BMR, but requires the documentation of the temperature at which the metabolic rate was measured. This makes BMR a variant of standard metabolic rate measurement that excludes the temperature data, a practice that has led to problems in defining "standard" rates of metabolism for many mammals.

BMR can be responsible for burning up to 70% of the total calories expended as you will expend energy no matter what you're doing, even when sleeping. Thus your Basal Metabolic Rate is the number of calories you'd burn if you were to stay in bed all day. Basal metabolic rate is usually by far the largest component of total caloric expenditure.

However, the Harris-Benedict equations are only approximate and variation in BMR (reflecting varying body composition), in physical activity levels, and in energy expended in thermogenesis make it difficult to estimate the dietary consumption any particular individual needs in order to maintain body weight. 2000 kilo-calories is often quoted but is no more than a guideline.

BMR Decreases with Age and with Loss of Lean Body Mass

Increasing muscle mass increases BMR.

Aerobic fitness level, a product of cardiovascular exercise, while previously thought to have effect on basal or resting metabolic rate (RMR), has been shown in the 1990s not to correlate with BMR, when fat-free body mass was adjusted for. New research has however come to light which suggests aerobic exercise does increase resting energy consumption. Illness, previously consumed food and beverages, environmental temperature, and stress levels can affect one's overall energy expenditure as well as one's BMR.

BMR is measured under very restrictive circumstances when a person is awake, but at complete rest.

An accurate BMR measurement requires that the person's sympathetic nervous system not be stimulated. A more common and closely related measurement, used under less strict conditions, is resting metabolic rate (RMR).

BMR Facts

Studies published in 1992 and 1997 indicate the level of aerobic fitness of an individual does not have any correlation with the level of resting metabolism.

Both studies find that aerobic fitness levels do not improve the predictive power of fat free mass for resting metabolic rate.

Some studies suggest a minimum of 20 to 25 minutes of cardiovascular training per day can temporarily increase the basal metabolic rate by around 10%, owing to an increase in the metabolism of the working muscles required for recovery as well as storage of glycogen and other fuel sources used by the body like ATP and Creatine.

BMR Calculator

The BMR Calculator below will calculate your Basal Metabolic Rate (BMR) - the number of calories you would burn if you were to stay in bed all day. To see how many calories you burn performing certain activities see How to Count and Calculate Calories.

BMR/RMR Formula (Mifflin-St. Jeor Equation)

For Males:

BMR = (10 × weightkg) + (6.25 × heightcm) - (5 × ageyears) + 5

For Females:

BMR = (10 × weightkg) + (6.25 × heightcm) - (5 × ageyears) - 161

Examples

Male Example

Let's calculate the BMR for a 30-year-old man who weighs 80 kg and is 180 cm tall:

BMR = (10 × 80) + (6.25 × 180) - (5 × 30) + 5 BMR = 800 + 1125 - 150 + 5 BMR = 1780 calories per day

Female Example

Now, let's calculate the BMR for a 25-year-old woman who weighs 65 kg and is 165 cm tall:

BMR = (10 × 65) + (6.25 × 165) - (5 × 25) - 161 BMR = 650 + 1031.25 - 125 - 161 BMR = 1395.25 calories per day

These BMR values represent the estimated number of calories the body burns at rest to maintain basic life functions. It's important to note that actual calorie needs may vary based on factors such as activity level, muscle mass, and overall health.

Author Credentials: Ian was born and grew up in Australia. Since then, he has traveled and lived in numerous locations and currently resides in Montreal, Canada. Ian is the founder, a writer, and editor in chief for Disabled World. Ian believes in the Social Model of Disability, a belief developed by disabled people in the 1970s. The social model changes the focus away from people's impairments and towards removing barriers that disabled people face daily. To learn more about Ian's background, expertise, and achievements, check out his bio.