What is resting metabolic rate (RMR)?

The resting metabolic rate (RMR) is the number of calories the body requires at rest. It is important because any calorie intake above this resting metabolic rate (RMR) is stored as fat by your body. The RMR is a good estimate for those of us without access to complex laboratory testing of oxygen consumption and carbon dioxide gas production. The basic formula for estimating RMR at rest is:

Body weight (pound) x 10 = RMR
or
Body weight (kilogram) x 22 = RMR

The RMR, however, is dependent on both your weight and your activity level. The more active you are, the more energy you expend and the more calories it takes to fuel you. This is why many and various "diet" plans work. It's not rocket science - it is simple math. They simply assist you to burn more or consume fewer calories than your body requires as maintenance.

At rest, your body burns 1,400 to 1,900 kcal (kilograms) a day. (A kilocalorie is the same amount of energy as a calorie, except that we use the term "calories" when we're talking about food and "kilocalories" when we're talking about exercise.) This is your "resting metabolic rate." This is the energy your body spends just keeping you alive, the energy it uses to keep your heart beating, to keep your blood flowing, to digest your food, and to breathe.

Your resting metabolic rate is approximately one kcal per kilogram of body weight per hour. (To find your weight in kilograms, divide your weight in pounds by 2.2.) If you weigh 132 pounds, or 60 kilograms, you will burn 60 kcal an hour. Then multiply this hourly number by 24 hours to get your expenditure per day. A person weighing 60 kilograms would burn 1,440 kcal a day even doing nothing. Likewise, a person weighing 90 kilograms, just about 200 pounds, would burn 90 kcal an hour and 2,160 kcal a day. Ideally, you should expend 3,500 kcal of energy a week in exercise above and beyond your resting metabolic rate.

Resting metabolic rate (RMR) is the rate at which your body expends energy at rest -- simply being alive and doing all the things a body does at rest, such as taking in and expelling air and pumping blood. At rest, a man or woman who weighs 155 pounds (70 kilograms) will expend about 1.2 calories per minute, or about 72 calories per hour, assuming he or she doesn't do anything else (your weight in kilograms roughly equals the number of calories you'll expend in an hour at rest). Add or subtract 10 percent for every 15 pounds above or below 155; subtract 4 percent for every 10 years over age 25. Your RMR accounts for about 60 to 75 percent of the calories you expend in a day. Thus even a slight increase in RMR will have significant benefits.