Resting Metabolic Rate Test
What is a Resting Metabolic Test?
Resting Metabolic Rate (RMR) is the number of calories required by the body to maintain basic functions such as heartbeat, breathing, temperature regulation, and brain activity. A standard RMR test with a Fitnescity partner involves using a metabolic cart and indirect calorimetry, the clinically recommended and industry reference standard of testing, to measure the number of calories burned per day at rest. Whether your goal is to lose, gain, or maintain weight, this information is extremely valuable for designing a personalized weight management program.
What is RMR?
The amount of energy, or calories, humans expend per day is referred to as Total Energy Expenditure (TEE). This number is the sum of RMR, diet-induced thermogenesis, and activity energy expenditure. Diet-Induced Thermogenesis is the energy expended from digesting and absorbing food (yes, eating burns calories), and Activity Expenditure is the energy spent on movement – everything from walking to the bathroom to completing a heavy lift. Resting Metabolic Rate (RMR) is the number of calories required by the body to maintain basic functions such as heartbeat, breathing, temperature regulation, and brain activity. This can also be referred to as basal metabolic rate or BMR.
To get the most accurate Resting Metabolic Rate results, all other causes of energy expenditure must be mitigated. This is why fasting and avoiding exercise before an RMR test is required.
How does an RMR test work?
So, how does an RMR test determine daily resting metabolic rate? Energy, in scientific terms, is called ATP. The creation of ATP involves converting macronutrients and oxygen into carbon dioxide, water, and heat.
By measuring the volume of oxygen consumed versus the volume of carbon dioxide expelled within a set time period, a metabolic cart can determine the rate of energy burn and extrapolate total daily resting energy expenditure. This is done via indirect calorimetry.
The Technology
Indirect Calorimetry is the clinically recommended method of measuring energy expenditure via respiratory gas exchange. The Law of Conservation of Energy (energy cannot be created or destroyed, only changed) set the stage for using indirect calorimetry to estimate the amount of energy expended; by measuring relative amounts of oxygen and carbon dioxide, conclusions can be drawn not only about energy (calories) expelled but the substrates used. Burning one calorie requires about 208.1ml of oxygen, so the precise measurement of oxygen uptake by a metabolic cart allows for the accurate calculation of daily calories.
Your Appointment
What happens during an RMR test? You will arrive to the test center 15 minutes prior to your appointment having followed the proper pre-test protocols. Upon arrival, the center will provide any necessary paperwork and bring you back to their testing space. You will sit or lie comfortably, and the test operator will secure the Indirect Calorimeter RMR mask over your nose and mouth. For best results, you should remain still, relaxed, and as comfortable as possible without falling asleep. The test lasts about 10-15 minutes, during which you will breathe normally. The technician will monitor the quality of data being collected to ensure best results.**
The results of the test may be inaccurate if the pre-test protocols are not properly followed. The accuracy of your results can also be affected by certain medications, medical conditions, acute infections and, for females, pregnancy, breast feeding and menstruation. You should let the testing staff know prior to the test if any of these apply, including the use of non-prescription medications. You should immediately report any unusual feelings that are of concern to the test staff during the test.
What are the benefits of an RMR?
Whether your goal is to lose, gain, or maintain your weight, this information is extremely valuable for designing a personalized weight management program. Knowing the amount of energy you use at rest will help you better understand the amount of energy you need from food.
Your resting metabolic rate is influenced by your age, gender, the amount of body fat and muscle you have, the amount of exercise you do, your ethnicity, as well as by a number of environmental factors like smoking and climate. Two people with the same weight and height can have very different metabolic rates and energy (caloric) needs.
How do I prepare for an RMR?
Following the proper testing protocols for a resting metabolic test is of the highest importance to ensure accuracy. RMR, food, caffeine, and exercise all contribute to one's daily Total Energy Expenditure. So, in order to isolate the calories associated with basic functioning, these variables must be controlled:
- You must complete a 12-hour fast prior to your RMR test
- You must not consume alcohol or caffeine 12 hours prior to the test.
- You must avoid moderate to vigorous exercise at least 24 hours prior to the test.
- Your commute to the testing location should be relatively stress free, so plan extra time. Avoid brisk walking, running or taking a lot of stairs.
- Attire: No specific attire is required.
How often should I test?
How often you should test depends on the intensity of your training/nutrition plan. We typically recommend testing every 3, 6, or 9 months:
Making changes to your fitness or nutrition plans can have a significant effect on your metabolism. Because of this, depending on what changes you make, we recommend testing more frequently to ensure your caloric intake is growing (or shrinking) to meet your body's needs.
What results are included with an RMR?
The Resting Metabolic Rate test provides two* very valuable pieces of data in understanding your metabolism: REE and RQ.
Resting Energy Expenditure (REE): Resting Energy Expenditure (sometimes used interchangeably with RMR) is the number of calories burned daily when the body is at mental and physical rest.
Respiration Quotient (RQ): The Respiration Quotient (RQ) represents the volume of carbon dioxide released over the volume of oxygen absorbed during respiration. This number is capable of indicating what substrates the body is using to produce energy – specifically under the conditions of an RMR test – at rest.
How does RQ indicate energy sources? Depending on the substrates being metabolized for energy (carbohydrates, fats, or proteins), varying levels of CO2 are released as by-products, causing RQ to vary from about .70 to 1.00.
Carbohydrates are oxidized via the aerobic system: Equal amounts of carbon dioxide are exhaled as oxygen is absorbed, returning an RQ of 1.00.
Fats are metabolized via the anaerobic system: Unequal amounts of carbon dioxide are exhaled as oxygen is absorbed, returning an RQ of about .70.
What is a “normal” RMR?
There are several generally accepted equations to calculate metabolic rate, but many lifestyle variables can vary your individual calorie burn from the average. This is what makes finding out your actual RMR so important. The Mifflin St. Jeor Equation is one of these industry standard formulas which calculates RMR based on age, height, and gender:
Equations like this are a great starting place for estimating your RMR, but in order to build an effective nutrition plan it is important to have accurate information tailored to your body. The RMR test uses state-of-the-art technology to provide all the data you need to get started.
What factors influence metabolism?
There are many factors that can contribute to having a higher metabolic rate. Being aware of which factors you can control or improve can help you increase or decrease your metabolic rate to reach your goals.
Body Fat Percentage
Your RMR depends on the amount of fat you have. If your body fat percentage is high, your RMR might be lower than that of an individual with a lower body fat percentage.
Weight
A smaller body requires fewer calories to maintain the same physiological functions, whereas a larger body requires more calories.
Also, during weight loss your body may try to conserve energy in response to a lower calorie intake, this can also cause a reduction in RMR.
Exercise
Physical exercise not only influences body weight by burning calories, it also helps raise RMR by building extra muscle. The greater the exercise intensity, the longer it takes the body to recover, which results in a longer and higher excess post-exercise oxygen consumption (EPOC).
Diet
Fasting or serious abrupt calorie-reduction can dramatically reduce the RMR by up to 30 percent. Likewise, restrictive, low-calorie weight-loss diets may cause the RMR to drop by as much as 20 percent.
Age
The metabolic rate declines with age because of loss of skeletal mass and increased percentage of fat tissue.
Height
Taller people typically have greater body surface area and more lean body mass. As a result, they can have a higher RMR.
Body Temperature
For every increase of 0.5 degrees C in internal temperature of the body, the RMR increases by about 7 percent. Therefore, a person with a fever of 42 degrees C (about 4 degrees C above normal) would have an increase of about 50 percent in RMR.
External Temperature
Temperature outside the body affects the resting metabolic rate. Exposure to cold temperature causes an increase in the RMR, as the body tries to create the extra heat needed to maintain its internal temperature. A short exposure to hot temperature has little effect on the body's metabolism because of compensatory increases in heat loss. However, prolonged exposure to heat can raise the RMR.
Genetics
Some people are born with faster metabolisms, while others naturally have slower metabolisms.
Hormones
Some hormones can increase or decrease metabolic rate. For instance, the thyroid hormones regulate a portion of metabolism. An individual who has hypothyroidism can have a low RMR.
FAQs
Why should I test with Fitnescity?
By booking with Fitnescity, you receive easy-to-understand digital insights, a personalized dashboard that allows you to view your progress over time, and a physician follow-up call so you can go over your results in depth.
*Individual location results may vary **Individual location process may vary
Fitnescity does not provide medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified medical professional if you have any questions about your results.