What is BMR or Basal Metabolic Rate?

Understand and calculate your basal metabolic rate to lose weight

definition of basal metabolic rate
Neil Webb/ Ikon Images/ Getty Images

Basal metabolic rate (BMR) is the total number of calories that your body needs to perform basic, life-sustaining functions. These basal functions include circulation, breathing, cell production, nutrient processing, protein synthesis and ion transport. You can calculate basal metabolic rate using a mathematical formula. 

Definition of Basal Metabolic Rate vs. Resting Metabolic Rate

Many weight loss and exercise guides use the terms basal metabolic rate and resting metabolic rate (RMR) interchangeably.

And the fact is that these two terms are very similar. But there is a slight difference in the definition of BMR and the definition of RMR that is helpful to understand.

  • Definition of Basal Metabolic Rate. A measurement of the number of calories needed to perform your body's most basic (basal) functions, like breathing, circulation and cell production. BMR is most accurately measured in a lab setting under very restrictive conditions. 
  • Definition of Resting Metabolic Rate. A measurement of the number of calories that your body burns at rest. Resting metabolic rate is usually measured in the morning before you eat or exercise and after a full night of restful sleep. 

As you can see, the definitions of RMR and BMR are almost identical. Your resting metabolic rate should be an accurate estimate of your basal metabolic rate. Because the terms are similar, many fitness and weight loss experts use both terms to describe the same thing.

But the term resting metabolic rate is more common.

How to Calculate Basal Metabolic Rate

If you want to lose weight, it's helpful to calculate your BMR. You can either find the number using a formula designed by scientists, you can get it tested in a lab, or you can use an online calculator. There is no method that is perfectly accurate, but a lab test will probably give you the best estimate.

But since lab tests can be costly, many dieters and exercisers use one of the other two methods to determine basal metabolic rate.

- Use an online BMR calculator. Put your height, weight and age into this online calculator to find your basal metabolic rate.

- Calculate your own BMR. The Harris-Benedict Equation is often used to estimate basal metabolic rate.

  • Men:  BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) - (5.677 x age in years)
  • Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) - (4.330 x age in years)

How to Change Your Basal Metabolic Rate

Your BMR is determined by a combination of factors. These include genetic factors, age, gender and body composition. There's not much you can do to control genetics, age or gender. But you can change your body composition to boost metabolism.

So how do you change your BMR? Build muscle!  Even when your body is at rest, lean muscle mass will burn more calories than fat. And you don't even have to be a bodybuilder to see benefits.

Several studies have shown that after just a few weeks of resistance training you may be able to see a 7-8% increase in resting metabolic rate.

How to Use BMR for Weight Loss

Now that you understand BMR you can use the number to help you lose weight. Your basal metabolic rate combined with two other factors can give you an idea of the total number of calories you burn each day.  

Total Calories Burned Each Day

  • Basal metabolic rate: 60-75% of total calories burned each day
  • Activity thermogenesis (non-exercise movement and exercise) 15-30% of total calories burned each day
  • Thermic effect of food (calories burned from eating and digestion) 10% of total calories burned each day

If you can burn more calories than you eat, you will create a calorie deficit. A calorie deficit of 500-1000 calories per day should result in a 1-2 pound weight loss per week.

Continue Reading