What is BMR?

Basal Metabolic Rate (BMR) is the amount of calories the human body burns at a basic function to sustain life. This includes breathing, circulation, cellular processes and production. Understanding BMR is important, should you want to understand how your body functions at an energy expenditure value. You can then adjust your nutritional intake for whatever goals you want to achieve.

While you may have heard of Basal Metabolic Rate, you may not have heard of Resting Metabolic Rate (RBR). With the former, this is the amount of calories you need for basic functions, while RBR is the number of calories your body is burning while at rest. This is also referred to as Resting Energy Expenditure (REE). These two calculations do differ, but one should be an accurate estimation of the other. 

Why Do People Calculate It?

People calculate BMR so they can understand what calories are required to allow their body to function at a basic rate. This is so that they can add on the calories burned through day to day life, plus what is burned when working out. At this stage, a person will know how many calories they need to eat every day to maintain their current weight. Deviating from this figure will cause either weight gain (calorie surplus) or weight loss (calorie deficit). Factoring in macronutrients which are protein, carbohydrates and fats, it is a recipe to hit the goal you’re aiming for.

An example of this is a BMR of 1800 calories + 700 calories from day to day living. You can then add working out, which equals to 2500 calories per day. If you’re only consuming 2200 calories, that will put the body in a calorie deficit which will result in losing weight. An estimated figure is that a cut of 3500 kcal a week will lead to a loss of 1 pound of fat per week. This is an achievable amount if factoring in regular exercise.

BMR Calculator

BMR Equation 

Step 1) Using the Mifflin-St- Jeor equation below, by inputting your specific age weight and height, it can generate your BMR without an activity measure in a simple calculation. The measurements are in metric, therefore if you record your measurements in imperial, you will need to convert them to Kg and cm before inputting into the equation.

It is important to remember to calculate the values in the brackets before completing the equation

Mifflin-St Joe Equation

BMR (kcal / day) = (10 x weight (kg)) + (6.25 x height (cm)) – (5 x age (yrs)) + s (kcal/day)

Where is s is +5 for males and -161 for females 

Example – 27 year old male who is 1.82m and weighs 97kg

BMR (kcal / day) = (10 x 97 (kg)) + (6.25 x 182 (cm)) – (5 x 27 (yrs)) + 5 (kcal/day)

970 + 1137.5 – 135 + 5 = 1977.5 BMR (kcal/day)

Step 2) To determine your calorie requirements you will need to multiply your answer above by one the multiplication which fits your situation best.

  • If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
  • Should you be lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
  • If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
  • Should you be very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
  • If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

1977.5kcal x 1.375 (lightly active) = 2719kcal/day

Summary

Basal Metabolic Rate (BMR) is the amount of calories the human body burns at a basic function to sustain life, this includes breathing, circulation, cellular processes and production.

Understanding BMR is an important factor to know should you want to be understanding how your body functions at an energy expenditure value so you can adjust your nutritional intake for whatever goals you are wanting to achieve.

People calculate BMR so they can understand what calories are required to allow their body to function at a basic rate so they can add on the calories burned through day to day life plus what is burned during working out.