Understanding BMR – What it is and why it’s important

The notion of calories in vs. calories out is becoming challenged more and more. This post does a good job of explaining some of science behind why a caloric deficit is not always the best way to lose weight. 

What is BMR?

We get this question a lot.

BMR stands for basal metabolic rate.  It is the amount of energy expended while at rest.  Basically said, BMR = how many calories your body burns in one full 24-hour day, while being completely sedentary.

Metabolism as a Medical Health Exercise Concept

Why is BMR important?

Knowing your BMR is the first step in getting an idea of how much fuel (ie: calories) you need to eat to keep your body going.  This is especially important when factoring in weight loss.  Contrary to what many people believe, eating less is not always the answer to losing weight.  If you eat too little, your body can retaliate and hang onto that extra layer of adipose tissue (fat) for dear life.  How can that be?  Think “survival of the fittest”.

When humans were cavemen and cavewomen, they ate to survive.  When food was abundant, they ate.  When food was scarce, they fasted.  To survive, their metabolism slowed when food was scarce to ensure the body has enough fuel to make it to the next “feeding”.  When food was plentiful, metabolism sped up to fully utilize and maximize all the energy that was available.

Not much has changed in regards to metabolism.  The connection between caloric intake and metabolism is strong.  Many fall into the diet trap of continuously lowering their caloric intake because their weight loss comes to a standstill.  This is a dangerous downhill spiral that will need some undoing.  By constantly lowering your caloric intake, your body goes into survival mode and will burn far less than it should be in order to preserve what little fuel you are giving it.

The less you eat, the slower your metabolism becomes.  Increase your daily intake, and your metabolism will speed up.  I should mention, that a disastrous smorgasbord is not a good thing and will lead to your body storing fat… quickly.

To get your metabolism to its optimal performance level, you have to give your body the minimum it requires to function.

How to calculate BMR:

Women: BMR = 655 + (4.35 x weight in lb) + (4.7 x height in inches) – (4.7 x age in years)

Men:  BMR = 66 + (6.23 x weight in lb) + (12.7 x height in inches) – (6.8 x age in years)

Example:  I am 32 years old, 5’3.5”, 114lbs

BMR = 655 + (4.35 x 114) + (4.7 x 63.5) – (4.7 x 32)

BMR = 1298.95 calories

The minimum amount of calories I should be eating on a daily basis is about 1299.

Knowing your BMR is the first step in understanding your nutrition needs.  Keep an eye out for a follow up post on TDEE (total daily energy expenditure) and how it relates to your weight loss!

Lianne Gong is a former US Swimming competitive swimmer and water polo player. After spending over a decade competing at a national level, she has dedicated the past 11 years to coaching/training athletes in the pool, on the land, and in the gym.