What is basal metabolic rate (BMR)?

The basal metabolic rate measures the minimum number of calories your body needs to perform necessary functions. These functions include: 

  • Breathing
  • Blood circulation throughout your body
  • Growing hair and skin
  • Keeps your body's temperature in balance
  • Maintaining the levels of a variety of chemicals


Your BMR accounts for 70% of the calories you burn every 24 hours. Other ways your body uses calories include exercise and general physical activity. BMR is affected by body mass, height, age, sex, genetics and more. The most important factor is that your weight doesn't come from fat, especially your muscle.


What can affect your BMR?

We all know that what affects our bodies is different for each of us, but there are a few things we all have in common when it comes to our BMR. Let's take a look at what they are!


  • Body size – As a general rule, larger adult bodies have more metabolizing tissue and a larger BMR.
  • Body fat – Fat cells are pretty lazy when it comes to burning calories. They burn fewer kilojoules than most other tissues and organs in the body.
  • Age – As we age, our metabolism naturally slows down for a couple of reasons. First, we lose muscle tissue, and second, our hormones and nervous system change.
  • The amount of lean muscle tissue and overall body composition – Your muscles burn calories (like calorie) quickly. 
  • Gender – Men have faster metabolisms because they tend to be larger 
  • Genetics – Your metabolic rate might be influenced by your genes.
  • Environmental temperature – If it's really cold or really hot out, your body has to work harder to keep your normal body temperature, which increases your BMR.


How do you measure your BMR?

Estimation with math. There are several equations you can use to estimate your daily BMR. One called the Harris-Benedict Equation, is a formula that uses your height, weight, age, and gender to help determine your BMR. 

  • The Harris-Benedict Equation for males assigned at birth (MAABs)


66 + (13.7 x weight in kg) + (5 x height in cm) – (6.8 x age in years)

For example, a man weighing 88 kg and standing 179 cm at the age of 33 would have a BMR of 1942.


  • The Harris-Benedict Equation for females assigned at birth (FAABs)


655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 x age in years)

For example, a woman weighing 63 kg and standing 167 cm at the age of 29 would have a   BMR of 1422.



How to increase your BMR?

  1. Get more exercise. 
  2. Weightlifting
  3. Make sure you eat your daily meals, especially breakfast.
  4. Consume more of fat-burning food.
  5. Sleep well every night. 


What is resting metabolic rate (RMR)?

Your resting metabolic rate is the amount of energy your body needs to function at rest. In addition to basic bodily functions, RMR takes into account additional low-effort daily activities. These activities include

  • Eating
  • Walking for short periods
  • Consuming caffeine
  • Sweating or shivering 
  • Basic neurological functions


The Mifflin-St Jeor Equation created in the 1990s provided and alternative and more valid estimate of PMR. The equations for males and females are:

  • For men: (10 x weight in kg) + (6.25 height in cm) – (5 x age in years) +5 

For example, a man weighing 88 kg and standing 179 cm at the age of 33 would have a BMR of 1839


  • For women: (10 x weight in kg) + (6.25 height in cm) – (5 x age in years) – 161 

For example, a woman weighing 63 kg and standing 167 cm at the age of 29 would have a BMR of 1368.


Calculate your total daily expenditure

If you want to know exactly what you're burning each day, calculate your Total Daily Energy Expenditure (TDEE). Using scientifically valid calculation methods, TDEE estimates the amount of energy (or number of calories) your body burns over a 24-hour period. It takes into account how much energy your body burns at rest, your typical level of physical activity, and the thermic effect of food metabolism. 


How Is TDEE Calculated?

There are several equations you can use to calculate your TDEE, but the Mifflin-St Jeor equation is one of the most commonly used because it is considered the most accurate by experts at the American Council on Exercise (ACE). It first uses your gender, age, height, and weight to estimate your basal metabolic rate (BMR). It then determines the appropriate activity multiplier based on your activity level input, providing an estimate of your TDEE.

Once your BMR has been determined, then you must multiply it by one of the following values that apply to most to your activity level:

  • Sedentary = 1.2
  • Lightly active = 1.375
  • Moderately active = 1.550
  • Very active = 1.725
  • Extra active = 1.9


Why knowing your BMR is important?

It's really important to know your Basal Metabolic Rate, whether you're aiming to maintain your weight, lose a few pounds, or even put a few on! Your BMR is a fantastic guide to help you figure out how many calories you should be eating to achieve your goals. If you're aiming to lose weight, just eat a little less than your BMR (or maintenance calories). And, if you're ready to gain a few extra pounds, go ahead and eat more! 


What are the limitations of BMI?

BMI is a great way to make sure your weight is on track. It uses your weight and height to give you a number, but it doesn't take into account your age or sex. 


It's perfectly normal for women to have more body fat than men with the same BMI. Similarly, older individuals tend to have a little more body fat than younger people with the same BMI. Your BMR can drop by up to 15% if you lose lean muscle tissue, too.


For all these reasons, BMI might not give us the full, detailed picture we need to know whether a person's weight is healthy.