How to Calculate Your Basal Metabolic Rate (BMR) (2024)

Your basal metabolic rate (BMR) is the minimum level of energy required to sustain vital functions such as breathing, digestion, and circulation—all of the bodily functions that happen beyond your control.

Your BMR is just one number you need to know if you're trying to lose weight.Losing weight is all about calories—the ones you burn and the ones you eat. All of the calories you burn in a day isknown as your total daily energy expenditure (TDEE). Your BMR is one component of your TDEE. If you can increase your BMR and thus your TDEE, you can burn more calories.

Measuring Your BMR

There are several formulas for calculating your BMR, and you can easily use an online calculator to do the work for you. However, there is a common formula many experts use to estimate BMR, so get out your calculator and see what you can come up with.

Revised Harris-Benedict Formula

The formulas used to calculate BMR are different for men and women and they've been revised since they were originally created. These are the revised Harris-Benedict BMR equations:

• Male: (88.4 + 13.4 x weight in kilograms) + (4.8 x height in centimeters) – (5.68 x age)
• Female: (447.6 + 9.25 x weight in kilograms) + (3.10 x height in centimeters) – (4.33 x age)

When using these formulas, your weight is in kilograms and your height is in centimeters and you will need to do a conversion if you normally use pounds and inches. For example, a 42-year-old male who is 5 feet 8 inches (173 centimeters) tall and weighs 200 pounds (91 kilograms) would use these numbers in the equation:

(88.4 + 13.4 x 91) + (4.8 x 173) - (5.68 x 42) = 1900 calories burned each day just to keep the body alive.

Online Calculators

You can also try online tools to calculate your BMR. These calculators usually involve inputting your sex, height, weight, and age to estimate your BMR. These calculators use the known formulas to make a guess based on your information.

Resting Metabolic Rate vs. Basal Metabolic Rate

Resting metabolic rate(RMR) and basal metabolic rate are two different measurements. As the name suggests, RMR is the number of calories your body burns while at rest. But BMR is the number of calories your body burns just by existing.

These are often usedinterchangeably, but BMR is more accurate. When measured in a lab, the test is done in a dark room after you wake up from eight hours of sleep and 12 hours of fasting toensure that your digestive system isn't very active. The RMR measurement is much less restrictive.

Factors That Influence Your BMR

Some situations temporarily affect your BMR, such as eating spicy foods or going out in frigid weather. But there are only a few things that can affect your BMR for the long term.

• Age:BMR usually decreases with age, which means many people may need to adjust their diet as they get older to avoid weight gain.
• Weight: Heavier individuals have a higher BMR.
• Height: The taller you are, the more mass you are likely to have, influencing BMR. Height compared to weight also helps determine how much fat-free vs. fat mass you have, which also affects BMR.
• Sex: Men typically have a higher BMR than women due to higher muscle mass and bone density.
• Genetics: Your genetics could influence your BMR. This is a factor that formulas cannot determine or account for.
• Body composition: Muscle mass expends more energy than fat mass. The higher your muscle mass, the higher your BMR can be, but this only accounts for a small amount of your energy expenditure.
• Menopause:If you're going through it or have been through it, you already know your BMR usually goes down during this period of time, meaning you're burning fewer calories.
  

Can You Change Your BMR?

Changing body composition through weight training and, especially, high-intensity interval training can help.

Your BMR will increase while you exercise and for a time afterward, but this effect won't last. Building muscle mass increases your BMR somewhat, but this effect is minimal compared to other factors. Some foods might have the ability to increase your BMR for a time, but these effects are also minimal and short-lived.

Your best bet is to increase your activity level, which increases your active metabolic rate (AMR), or the total number of calories you burn each day. Find your approximate AMR by multiplying your BMR by a specific number that represents various activity levels. This number ranges from 1.2 if you are sedentary up to 1.9 if you are very active.

• Sedentary (little or no exercise): AMR = BMR x 1.2
• Lightly active (exercise 1–3 days/week):AMR = BMR x 1.375
• Moderately active (exercise 3–5 days/week):AMR = BMR x 1.55
• Active (exercise 6–7 days/week):AMR = BMR x 1.725
• Very active (hard exercise 6–7 days/week):AMR = BMR x 1.9

So, if the 42-year-old man used as an example above is sedentary, his AMR is about 2,280 (1,900 x 1.2). If he's very active, he's burning about 3,610 calories a day (1,900 x 1.9).

Frequently Asked Questions

What hormone is most responsible for determining basal metabolic rate?

The basal metabolic rate is mostly determined by the thyroid hormones T3 and T4, which respond to thyroid-stimulating hormone (TSH). T3 and T4 bind to mitochondria receptors, increasing adenosine triphosphate(ATP) production and increasing glucose use. ATP helps with the transportation and use of energy. These effects cause a higher cell metabolism.

What is a good basal metabolic rate?

Your basal metabolic rate isn't really "good" or "bad." It's just a piece of information you can use to understand your health, and to create goals and strategies related to your weight.

If you want to lose weight, you can work on lowering your basal metabolic rate, along with adjusting your calorie consumption to create a calorie deficit. And if you want to gain weight, your BMR helps you understand the minimum number of calories your body needs, so you can work to consume more than that.

A Word From Verywell

Understanding BMR can help you better understand your daily calorie needs, but keep in mind that it is only an estimate. If you are trying to change your body composition by losing or gaining weight, consider your BMR and activity levels. Remember that factors that are out of your control influence your BMR and calorie burn.

As you make changes in your eating pattern and exercise routine to change your body composition, remember it's a long-term, gradual process. Make small adjustments based on your results to fine-tune your diet and exercise plans and meet your goals.