Difference Between BMR and RMR

The key difference between BMR and RMR is that the BMR (Basal Metabolic Rate) is measured under more restrictive conditions than the RMR (Resting Metabolic Rate).

The amount of calorie expenditure in a person during the resting state can be measured in two methods. The two methods are measuring the Basal Metabolic Rate or the BMR and measuring the Resting Metabolic Rate or the RMR. The BMR refers to the basal energy expenditure during the resting state. This measurement assesses under restricted conditions. It will provide the energy expenditure at complete rest. The RMR refers to the resting energy expenditure. This measurement assesses under less restricted conditions. Obtaining the RMR of a person is a more practical method of measuring energy expenditure at resting state. The main difference between the BMR and RMR is the conditions put forward during the measurement process.

1. Overview and Key Difference
2. What is BMR
3. What is RMR
4. Similarities Between BMR and RMR
5. Side by Side Comparison – BMR vs RMR in Tabular Form
6. Summary

What is BMR?

BMR or the basal metabolic rate of a person is a measure taken under highly restricted conditions. It is the energy expenditure under an ideal resting state. BMR measures the amount of energy required in calories for the basic body functions such as breathing and functioning of the vital organs, blood circulation, etc. In brief, BMR measures the heat energy given off by the person under a perfect resting state.

The measurement of BMR takes place under restricted conditions. Hence, the person has to be at complete rest. The test conducts in a darkened room. The person should have a complete eight hours of sleep on the night prior under the supervision of the researcher. The person also requires fasting for 12 hours. The reading is taken in a reclining person, once the above needs are satisfied. Therefore, the measurement of the BMR or the basal energy expenditure is not a realistic process at all times.

Figure 01: BMR

Moreover, the measuring of the BMR takes place through a direct or an indirect calorimeter. It requires a lot of monitoring and preparation. The person should be well analyzed for the diet in order to confer the readings obtained for BMR.

What is RMR?

RMR or the Resting Metabolic Rate is the energy expenditure at the resting state. This test performs under less restrictive conditions. Thus, the person is not required to be closely monitored for the previous night sleep and diet patterns. Furthermore, it is not necessary to stay in the testing laboratory the previous night. Therefore, during the measurement of the RMR, the energy expenditure at resting state only considers. The diet of the person, the previous sports activities are not taken into consideration when measuring the RMR. Hence, the values obtained for RMR differs drastically to person to person and with time.

Figure 02: RMR

RMR also assesses using the indirect or direct calorimeter. This measurement is more practical because the measurements are obtained in a more realistic manner. Thus, RMR measures the energy expenditure of a normal person with the reduced workload. Due to the less laborious and the realistic nature of the RMR measurement, obtaining the resting metabolic rate of a person is more reliable and realistic than BMR.

What are the Similarities Between BMR and RMR?

BMR and RMR are two measures of calorie expenditure.
These rates measure the energy used in carrying out normal organ functions.
Besides, these measurements play a big role in monitoring weight loss and weight maintenance.
Also, both can be used as a base to estimate body energy needs.
Direct or the indirect calorimeter are two methods to measure them.
Both measures are taken in restrictive seating conditon.
Furthermore, both measurements are taken in the reclining position.

What is the Difference Between BMR and RMR?

BMR and RMR are two tests performed in resting stage to measure the metabolic rate. In both tests, there are a set of conditions that should be satisfied before taking the readings. However, there is some difference between BMR and RMR in those conditions. That is, the person who is undergoing BMR test requires to fast 12 hours prior to the test as well as should have an 8-hour sleep prior to the test. However, RMR does not require such conditions. Another difference between BMR and RMR is their reliability. RMR is more reliable than BMR since it measures energy expenditure under less restrictive conditions. BMR assesses the calorie expenditure under specific restrictive conditions.

The below infographic outlines the difference between BMR and RMR in tabular form for quick reference.

Summary – BMR vs RMR

BMR and RMR are two measurements that assess the energy expenditure under resting conditions. The key difference between BMR and RMR is the conditions used during the measurement process. BMR is measured under highly restricted conditions. In contrast, measurement of RMR takes place under less restricted conditions. Furthermore, RMR is considered as the more practical value than BMR.

Reference:

1.McMurray, Robert G., et al. “Examining Variations of Resting Metabolic Rate of Adults: A Public Health Perspective.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, July 2014. Available here

Image Courtesy:

1.”Indirect calorimetry laboratory with canopy hood”By Cosmed – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.”Resting Metabolic Rate”By Bmetabolism – Own work, (CC BY-SA 4.0) via Commons Wikimedia