Introduction:
Metabolism is a term that is coined to refer to all reactions that occur within every cell of the body to provide the body with the needed daily energy. Each food that is consumed every day comprises several essential nutrients, proteins, vitamins, and minerals. These are eventually absorbed into the bloodstream and are utilized by the body tissues after conversion into heat (the units of heat are denoted by the measurement of calories). The energy one derives from food or the calories hence are either immediately used for the various activities or eventually stored up by the body cells to be used later. The extra calories that one derives from the diet are usually stored as fat in the tissues.
The metabolic rate would be broadly defined as the number of calories that the body burns when it is still at rest. The higher the metabolic rate, the more the potential for preventing overweight tendency or obesity. With age, as a natural physiologic impact, individuals tend to lose the metabolic rate (where they would be burning fewer calories) that can lead to weight gain or obesity. The term metabolic rate is a misnomer according to health experts. The basal metabolic rate which is an important part of the physical metabolism is of two types. These are the BMR and the RMR.
What Are Different Types of Metabolic Rate?
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Basal Metabolic Rate (BMR): This is specifically a term that is used to denote the amount of energy one uses when they are either lying still or awake at any point in time. Simply put, the BMR of an individual is the minimum metabolic rate that is most crucial needed to keep the important organs of circulation such as the lungs, heart, and brain in proper working condition.
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Resting Metabolic Rate (RMR): RMR is a term similar to the BMR but also includes activities that comprise movements of the individual as well.
The difference between BMR and RMR can be simply put as follows: While the BMR can be easily measured when the individual is fully at rest, the RMR can further include small movements as well (such as walking for a short distance or getting up or sitting down for instance). Several research studies show that the RMR would be a slightly better and more accurate indicator of assessing daily energy needs in comparison to the BMR. This is because as the RMR takes movements into insight, the number of calories that are needed to burn will be the approximate answer that can let an individual identify the best way to lose healthy weight or how to gain healthy weight (based on the body type and needs).
The metabolic rates hence would vary further from individual to individual and several important factors can be measured by obtaining the RMR of an individual
What Is the Purpose of the Measurements of RMR and BMR?
Dieticians as well as nutritionists along with nutrition experts across the globe have indicated that the BMR (basal metabolic rate) and the RMR (resting metabolic rate) are interchangeable terminologies (though slightly different) that can assess an individual's need for burning calories. These measurements are a science in itself because they can help further determine how many calories an individual should be consuming either for weight loss, weight gain, or for healthy weight maintenance
The simplest way of calculating the metabolic rate of BMR is by the revised Harris-Benedict Equation.
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For Calculating BMR in Male: (88.4 + 13.4 x weight in kilograms) + (4.8 x height in centimeters) – (5.68 x age), or, BMR = (6.23762 × weight in pounds) + (12.7084 × height in inches) – (6.755 × age in years) + 66.473
- For Calculating BMR in Females: (447.6 + 9.25 x weight in kilograms) + (3.10 x height in centimeters) – (4.33 x age), or, BMR = (4.33789 × weight in pounds) + (4.69798 × height in inches) – (4.6756 × age in years) + 655.095
Though less accurate than the lab-based tests, the accuracy of the revised Harris-Benedict equation is nearly 70 percent. This means that it can be possible for the calculation through this equation to lead to major errors in estimating the true calorie needs of the individual. However, it is still deemed to be one of the best home assessment tools to determine calorie needs and the Harris-Benedict equation was originally set in the 1920s with the average RMR for women being considered ideal at 1400 calories per day and 1600 calories for men per day.
As per current nutrition research, recent reference levels have changed and can vary for a broad range in sedentary lifestyle adults or individuals with the RMR varying between 1200 to 3000 calories roughly per day in both men and women.
When these parameters of metabolism need to be assessed or measured clinically in the lab setting, the BMR is always assessed first in the morning only. This assessment is done when a patient is at complete rest after an overnight fast and would have had no proper exercise for at least the previous 24 hours. RMR on the other hand, as elaborated earlier includes the smaller movements and is measured after at least 15 minutes of rest for the individual, however with a few other restrictions. When both BMR and RMR in a lab setting need to be assessed for considering a patient's health status, then the time of the day does not matter as such for performing these tests.
The lab-based test is the indirect calorimetry test that is deemed the most common as well as the reliable method to measure RMR. Even though the benefit of this method is that it is non-invasive, it is not considered economical or rather expensive and time-consuming by many individuals.
Conclusion:
RMR and BMR are only the ones that one can use for determining the number of calories that can be burned and how one can use it to fix up weight loss or weight gain or maintain weight sustenance goals. While several formulas or mathematical equations exist to determine the BMR and RMR by oneself, a nutritionist or dietician can advise the laboratory tests to determine the right course of physical activity, rest, and diet for the patient. It should be noted that only rough estimates of the caloric needs are always important. It helps to prioritize a healthy balanced diet, physically active lifestyle, and adequate sleep to sustain systemic health.
