Basal Metabolic Rate - How to Calculate Your BMR

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Unless you've been living on another planet in the past 10 or so years, you've probably heard about your Basal Metabolic Rate, also known as your BMR.

What is Your BMR

So, what exactly is BMR and what does it really mean?  Your BMR refers to the to the minimum level of energy required to sustain vital functions such as breathing, digestion, and circulation...all the bodily functions that happen beyond our control.

Measuring Your BMR

There are a crazy number of formulas out there for calculating your BMR, and, as always, you can easily use an online calculator to do the work for you.

However, there is a common formula many experts use to estimate BMR, so get out your calculator and let's see what we can come up with.

Revised Harris-Benedict Formula

The BMR formulas are different for men and women and they've been revised since they were originally created:

Male: (88.4 + 13.4 x weight) + (4.8 x height) – (5.68 x age)

Female: (447.6 + 9.25 x weight) + (3.10 x height) – (4.33 x age)

When using these formulas, your weight is in kilograms and your height is in centimeters.

So, let's say you're a 42-year-old male who is about 5'8" (173 cm) and weighs 200 lbs (91 kg).  Here's what his BMR would be:

(88.4 + 13.4 x 91) + (4.8 x 173) - (5.68 x 42) = 1900 calories burned each day just to keep the body alive.

RMR vs. BMR

I want to point out that, In the fitness world, there are two different measurements here.

  One is called your Resting Metabolic Rate and the other is what I'm talking about now, your Basal Metabolic Rate. 

In the real world, we typically use these interchangeably, but in the fitness world, were you to get it measured in a lab setting, your BMR is much more accurate.  It's actually measured in a dark room after you wake up from 8 hours of sleep and 12 hours of fasting.

  This ensures that your digestive system isn't working.

That's pretty hardcore, which is why when we say BMR, we probably mean RMR which is much less restrictive.

What Does Your BMR Mean?

Your BMR is just one number you need to know if you're trying to lose weight.  Losing weight is all about calories - The ones you burn and the ones you eat.  Your BMR is just one component of all the calories your burn in a day, also known as your Total Daily Energy Expenditure (TDEE).

Things that influence your BMR

There are things that will temporarily affect your BMR, such as eating spicy foods or going out in really cold weather, but there are only a few things that can affect your BMR for the long-term.

  • Menopause - If you're going through it or been through it, you already know your BMR usually goes down during this period of time, meaning you're burning fewer calories.
  • Weight Training - The good news is, building muscle is an excellent way to increase your BMR for the long-term
  • Age - The bad news is, your BMR will usually decrease as you age, which means many of us may need to adjust our diets as we get older to avoid weight gain.

    Sources:

    FitnessHealth101.com. "Variables That Affect Your Basal Metabolic Rate (BMR)." FitnessHealth101.com. FitnessHealth101.com. Web. 02 Feb. 2016.

    Kelly, Mark P., Ph.D. "Resting Metabolic Rate: Best Ways to Measure It-And Raise It, Too." American Council on Exercise. ACE. Web. 2 Feb. 2016.

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