Karen Marcouiller

Personal Trainer and Health Coach

National Sports and Conditioning Association (NSCA)

American Council on Exercise (ACE)

What is Metabolism and Why is Mine So Slow?!

January 4, 2018



Most of us know the faster metabolism is, the easier it is to lose weight.  We also know that metabolism slows as we age.  (Most of us have first-hand experience with that phenomenon!) But what exactly is metabolism and how is it measured?


Metabolism is the rate at which we burn calories.  So our resting metabolic rate (RMR) is how many calories we burn at rest, through respiration, brain and heart function and the other work our body has to do just to stay alive.  It’s dependent on age, weight, and height.  There are many formulas to estimate our RMR. I like to use the Mifflin-St Jeor Equation, which follows:


Male: (10 x weight) + (6.25 x height) – (5 x age) + 5

Female: (10 x weight) + (6.25 x height) – (5 x age) – 161


weight in kilograms, height in centimeters, age in years

To convert pounds into kg, divide pounds by 2.2     To convert inches into cm,  multiply inches by 2.54


Following are sample calculations for a 52-year-old woman who is 163 cm (5’4”) and weighs 64 kg (140 lb)

(10*64) +(6.25*163)-(5x52)-161      /     640+1019-260-161 = 1238


After calculating the RMR, exercise is factored in. Depending on your exercise level, the RMR is multiplied by anything from 1.2 to 1.9.


This provides us with maintenance calories - the amount of calories you could consume each day and neither lose or gain weight.  To lose weight, make your daily calorie goal usually 20% less than this.  It may be more or less in certain situations. For information on what could be slowing your metabolism down, click here, or call me!


I’d love to provide you with more specific information about your metabolism and reaching your strengthening and weight loss goals.  Contact me!

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