The Body's Slow Burn
by Carmichael Training Systems on September 17, 2006 in Health & Nutrition
Understanding your Resting Metabolic Rate and its powerful connection to weight management and training
By Jay T. Kearney, Ph.D.
In our mania to count every calorie we eat and drink, burn during exercise, or cut from our diet, there's a calorie number that's often overlooked: Resting Metabolic Rate (RMR). This is the minimum number of calories your body uses every 24 hours to keep you alive. It varies from person to person, and knowing your RMR is an important part of reaching your desired bodyweight or fitness level.
RMR 101
Sedentary and active individuals can use their respective RMR's for different purposes. Let's say Couch Potato Bob and Triathlete Chuck both have identical RMR's of 1,700 Calories per day. Bob's RMR can represent up to 80 percent of the calories he burns throughout the day, while Chuck's RMR, because he's so active, may only cover 50 percent of his total energy needs for the day.
Sedentary people like Bob need to know their RMR in order to reduce or maintain their caloric intake to avoid gaining weight. At the other end of the spectrum, Chuck and other active types want to know their RMR's because an accurate tally of their daily caloric needs helps them make sure they eat enough to optimally support their bodies and their training. If they don't eat enough to meet these demands, they'll simply run out of gas before completing quality workouts.
RMR isn't a set number. It changes based on a variety of factors: gender, age, height, hormones, and disease. But the most important determinant in your RMR is the amount of lean muscle mass on your body. The more you have, the higher your RMR will be. This is because it takes 10-15,000 Calories a year to support a pound of muscle, and having more muscle means you can burn more calories each time your exercise. Losing a pound of that muscle means you have to find some other way to burn off those 10-15,000 Calories or else they'll turn into 3-4 pounds of fat around your waist. Sticking to a regular exercise plan will develop your lean muscle mass and keep your metabolic rate up as well.
Determining and Using Your RMR
To measure your RMR, you'd determine the amount of oxygen you're consuming, since the volume of O2 you breathe in and use is directly related to the number of calories you're burning. As RMR measurement devices aren't readily available to the public, a number of scientific equations have been developed to provide a reasonable estimate. We at CTS consider the Mifflin-St. Jeor method featured on our Website: http://www.trainright.com/folders.asp?action=display&uid=11 to be one of the better ones available. Use it to figure out your RMR and then use the table below to determine how active your lifestyle is. Multiply your RMR by the appropriate lifestyle factor and add this number of calories to your RMR.
Now, the last step is to record the number of calories you burn during your workouts, which you can do with the help of a calorie-counting device such as Suunto's t6 wrist-top computer or other monitoring devices like pedometers or SRM cycling power meters. Once you have this final number, you can plug all three into the calculator below and get a reasonable estimate of the total number of calories you burn in a day.
By Jay T. Kearney, Ph.D.
In our mania to count every calorie we eat and drink, burn during exercise, or cut from our diet, there's a calorie number that's often overlooked: Resting Metabolic Rate (RMR). This is the minimum number of calories your body uses every 24 hours to keep you alive. It varies from person to person, and knowing your RMR is an important part of reaching your desired bodyweight or fitness level.
RMR 101
Sedentary and active individuals can use their respective RMR's for different purposes. Let's say Couch Potato Bob and Triathlete Chuck both have identical RMR's of 1,700 Calories per day. Bob's RMR can represent up to 80 percent of the calories he burns throughout the day, while Chuck's RMR, because he's so active, may only cover 50 percent of his total energy needs for the day.
Sedentary people like Bob need to know their RMR in order to reduce or maintain their caloric intake to avoid gaining weight. At the other end of the spectrum, Chuck and other active types want to know their RMR's because an accurate tally of their daily caloric needs helps them make sure they eat enough to optimally support their bodies and their training. If they don't eat enough to meet these demands, they'll simply run out of gas before completing quality workouts.
RMR isn't a set number. It changes based on a variety of factors: gender, age, height, hormones, and disease. But the most important determinant in your RMR is the amount of lean muscle mass on your body. The more you have, the higher your RMR will be. This is because it takes 10-15,000 Calories a year to support a pound of muscle, and having more muscle means you can burn more calories each time your exercise. Losing a pound of that muscle means you have to find some other way to burn off those 10-15,000 Calories or else they'll turn into 3-4 pounds of fat around your waist. Sticking to a regular exercise plan will develop your lean muscle mass and keep your metabolic rate up as well.
Determining and Using Your RMR
To measure your RMR, you'd determine the amount of oxygen you're consuming, since the volume of O2 you breathe in and use is directly related to the number of calories you're burning. As RMR measurement devices aren't readily available to the public, a number of scientific equations have been developed to provide a reasonable estimate. We at CTS consider the Mifflin-St. Jeor method featured on our Website: http://www.trainright.com/folders.asp?action=display&uid=11 to be one of the better ones available. Use it to figure out your RMR and then use the table below to determine how active your lifestyle is. Multiply your RMR by the appropriate lifestyle factor and add this number of calories to your RMR.
| Activity Factor | Description | Multiply RMR by: |
| Very light | Most of my work day is sitting or with some standing - relatively little physical activity | 0.2-0.3 |
| Light | Work involves some sitting, mostly standing and walking - example retail sales - light recreational activity | 0.5-0.6 |
| Moderate | Work involves sustained physical activity with little sitting - example UPS delivery person or mailman - active recreational pursuits | 0.6-0.7 |
Now, the last step is to record the number of calories you burn during your workouts, which you can do with the help of a calorie-counting device such as Suunto's t6 wrist-top computer or other monitoring devices like pedometers or SRM cycling power meters. Once you have this final number, you can plug all three into the calculator below and get a reasonable estimate of the total number of calories you burn in a day.
Carmichael Training SystemsCarmichael Training Systems was founded in 1999 by Chris Carmichael. From the beginning, the mission of the company has been to improve the lives of individuals we work with through the application of proper and effective fitness and competitive training techniques.
Whether your focus is recreational, advanced, or you are a professional racer, the coaching methodology employed by CTS will make you a better athlete.
