How to Calculate Resting Metabolic Rate

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Resting metabolic rate (also called RMR) is the rate at which your body burns energy when it is at complete rest. You can calculate your resting metabolic rate to see how many calories your body needs to perform basic functions like breathing and circulation. Your RMR or resting metabolic rate is part of your total daily energy expenditure (TDEE) or the total number of calories you burn each day.

What Is Metabolism and Metabolic Rate?

We often talk about metabolism as if it is a single mechanism in your body. But it's not. Metabolism—including resting metabolism—is a series of functions that are happening all the time. The rate at which those functions occur is your metabolic rate.

Your body converts the food you eat into energy in order to fuel both basic and complex functions like breathing or moving. This process is called metabolism. The entire metabolic process is a series of chemical actions that keep your body alive and healthy.

So how does metabolism work? Every food you eat contains nutrients. Your body absorbs the nutrients and converts them into units of heat—or calories. The energy—the calories—that are provided by the food are either used right away or stored for your body to use later. Extra calories are usually stored as fat.

What Is Resting Metabolic Rate?

Resting metabolism is the energy required by your body to perform the most basic functions when your body is at rest. These essential functions include things like breathing, circulating blood or basic brain functions. Resting metabolism is sometimes also called basal metabolism. Your basal metabolic rate (BMR) is the total number of calories your body burns at rest. You can calculate your resting metabolic rate to find out your personal number.

Everyone's resting metabolism or BMR is different. Factors that affect your resting metabolic rate include your weight, gender, age and body composition. For example, someone who is very large and muscular needs more energy (more calories) to maintain his body at rest than someone who is very small.

What Other Factors Affect Metabolism?

In addition to your resting metabolism, there are several other factors that affect the total number of calories that you burn each day.

  • We use energy to chew and digest food. Researchers call this the thermic effect of food (TEF). It makes up a very small part of your total energy requirements. 
  • You can also burn a lot of calories with exercise. For example, you might boost your metabolism with a daily walk or a vigorous workout at the gym.
  • Non-exercise movement also requires a lot of energy. Researchers use the term "non-exercise activity thermogenesis (NEAT)" to describe all of the calories that you burn doing basic movement throughout the day like carrying groceries, walking to your desk at work, or cooking dinner. 

How Do I Change My Metabolism to Lose Weight?

To lose weight effectively, you should know your resting metabolic rate and the total number of calories you burn each day (including exercise and NEAT). There are different ways to determine those numbers, but none is an exact science. Some gyms or medical centers offer metabolic testing services that may be more accurate.

Keep in mind that the number you get when you use calculate your resting metabolic rate is simply an estimate. Even if you go to the gym or to a lab, the number you get isn't exact. It is simply the best guess at the number of calories that your body will burn. This is helpful to know if you are trying to gain or lose weight. Some experimentation is always required to get your calories in (food intake) to balance out with calories out (metabolism) to reach your desired goal. 

Once you have a smart estimate of how many calories you burn each day, you can change your daily food intake or change your daily activity level to create an energy deficit. Sometimes weight loss experts call it a calorie deficit.

When you don't give your body the energy it needs, it burns stored energy (stored fat) as fuel instead. The result is that you lose weight and slim down. A weekly calorie deficit of approximately 3500 calories will result in roughly one pound of weight loss.