Basal Metabolic Rate

Diagram illustration about blood vessel of the human body
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Basal metabolic rate, or BMR, is a term you may encounter in discussions of obesity and metabolism.

What Is Basal Metabolic Rate?

Simply put, basal metabolic rate (BMR) is the minimum rate of energy expenditure needed to keep your body going at rest. So, even when you are sleeping or sitting perfectly still, your body needs to expend a minimum rate of energy in the form of calories just to keep all your organ systems and bodily functions going.

And that minimum rate of energy is the BMR.

How Is BMR Calculated?

Your BMR depends upon your age and your body mass index (BMI). Different formulas exist for calculating BMR, and some even incorporate your estimation of your daily physical activity and how physically fit you are in general, since this can affect BMR. Others account for ethnic differences which may influence BMR.

One commonly used BMR equation is the Mifflin – St. Jeor equation, as follows:

  • For a man: BMR = [10 x weight(kg)] + [6.25 x height(cm)] – [5 x age(y)] + 5
  • For a woman: BMR = [10 x weight(kg)] + [6.25 x height(cm)] – [5 x age(y)] - 161

The answer is given in calories. So, for example, for a 39-year-old woman who is 5 feet, 6 inches tall and weighs 150 lbs., her BMR would be 1,372 calories per day using this equation. To make it simpler, online BMR calculators do exist!

Having a higher BMR is favorable to maintaining a normal weight range, because it means your body uses up more calories just by resting.

This is what many commonly think of when the phrase “resting metabolism” is used. Thus, a higher BMR may be thought of as translating to a higher rate of metabolism at rest.

Can You Change Your BMR?

Increasing the amount of lean muscle on your body can increase your BMR—and if you already have a lot of lean muscle, your actual BMR may in fact be higher than the calculated result using the equation above.

Losing weight if you are overweight or obese will improve your BMR, as researchers have found that excess adipose (fat) tissue, particularly in the form of what is known as central adiposity (a large waist circumference, reflecting increased fat tissue along the waistline and abdominal organs), is associated with a lower-than-normal BMR.

Increasing your aerobic fitness can also help raise your BMR. Some examples of common activities that count as aerobic exercise are walking, swimming, jogging or running, cycling, dancing (such as Zumba) and cross-country skiing, to name but a few. Aerobic exercise has far-reaching health benefits, including preventing cardiovascular disease and cancer, improving cholesterol, improving lung function and improving brain health, to name but a few.

Getting enough sleep is also important for improving your BMR, since lack of sleep actually lowers the BMR. Another factor that can lower the BMR is chronic stress, so stress management is important for your BMR, too.

References:

Quiroz-Olguin G, Serralde-Zuñiqa AE, Saldaña-Morales MV, et al. Validating an energy expenditure prediction equation in overweight and obese Mexican patients. Nutr Hosp 2014;30:749-755.

Moreira H, Passos B, Rocha J, et al. Cardiorespiratory fitness and body composition in postmenopausal women. J Hum Kinet 2014;43:139-48.

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