The terms RMR and BMR are often used interchangeably. But do they really mean the same thing? Are they measured the same way? What are they trying to measure?
Metabolic rate represents the number of calories needed to fuel ventilation, blood circulation and temperature regulation. Calories are also required to digest and absorb consumed food and fuel the activities of daily life. Or put another way, metabolic rate is an estimate of how many calories you would burn if you were to do nothing but rest for 24 hours. It represents the minimum amount of energy required to keep your body functioning.
BMR is defined as Basal Metabolic Rate. BMR is synonymous with Basal Energy Expenditure or BEE. BMR measurements are typically taken in a darkened room upon waking after 8 hours of sleep, 12 hours of fasting to ensure that the digestive system is inactive, and with the subject resting in a reclined position.
RMR can be defined as Resting Metabolic Rate. RMR is synonymous with Resting Energy Expenditure or REE. RMR measurements are typically taken under less restricted conditions than BMR and do not require that the subject spend the night sleeping in the test facility prior to testing.
Both BMR and RMR are measured by gas analysis through either direct or indirect calorimetry, although a rough estimation of RMR can be acquired through an equation using age, sex, height and weight. This equation is the Mifflin-St.Jeor equation, and can be found on pg 174 of ACE’s Essentials of Exercise Science for Fitness Professionals. You can also find the equation online at: http://www.scientificpsychic.com/health/cron1.html
So are RMR and BMR the same? Mostly, except for the fact that BMR is going to be a slightly more accurate reading. However, both play a role in the process of weight loss and weight maintenance.
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