Knowing Your BMR Is Key To Achieving Fitness Goals. Here's How To Calculate It

News flash: Your body is burning calories all day (and night) long. Yep! By simply existing, you're torching calories. But how many cals you burn to sustain these bodily functions depends on one major factor: basal metabolic rate (BMR).

What does BMR mean, exactly? Basal metabolic rate (BMR) is the amount of calories your body burns while performing basic life-sustaining functions like breathing, growing hair, digesting food, and keeping your heart beating, says Alyssa Lombardi, exercise physiologist, running coach, and founder of Alyssa RunFit Coaching. “BMR is the minimum amount of calories that your body needs at rest.”

Meet the experts: Alyssa Lombardi, CPT, is an ACSM-certified clinical exercise physiologist, certified personal trainer, certified running coach, and founder of Alyssa RunFit Coaching. Cara Carmichael, CPT, is a NASM-certified personal trainer, OrangeTheory coach, and certified PN nutrition coach.

It's also important to know what it's not. Your day-to-day BMR number does not incorporate your activity levels or how much you exercise. It is the rate at which your body burns calories to perform essential bodily functions only. That being said, exercising more (or less) can change your baseline BMR in the long term (we'll get into this!).

BMR is extremely personal because the number is based on:

  • Height

  • Weight

  • Sex

  • Age

  • Muscle mass

  • Body fat

Knowing your BMR can help you stay in tune with weight management and how your body responds to life activities. “As your level of activity, exercise, and age changes, your BMR will change,” says Lombardi. “Checking it every so often can be helpful to know, so you can adjust your lifestyle to maintain a healthy weight.”

That's just a sneak peek of what BMR can do, but there’s a lot more this nifty stat can tell you. Keep scrolling for the details of calculating your basal metabolic rate, why knowing your BMR matters, and more from experts.

How To Calculate Your BMR

There are a few different ways to calculate BMR. Getting an exact and totally accurate BMR requires a DEXA scan, says Lombardi. “This is essentially a picture of your body that will tell you the make-up of your body’s fat, muscle, and bone density,” she says. However, DEXA scans use a low dose X-ray and require an in-person visit with your physician or other provider.

Because DEXA scans are not super accessible, Lombardi recommends an online calculator like Omni Calculator for an easier (and free!) measurement right at home. While less exact, studies show online calculators using the Harris-Benedict equation take into account your height, weight, age, and gender to give you a rough assessment of your BMR.

Since the Harris-Benedict equation does not factor in muscle mass or body fat there are limitations to its accuracy. You can estimate it yourself with the equation for women below.

Calculate your BMR: 655 + (9.6 x weight in kg) + (1.8 x height in cm) - (4.7 x age in years)

It’s also important to note that men typically have a higher BMR than women. Generally speaking, men are taller and have more muscle mass than women, resulting in a higher BMR, explains Lombardi. The more muscle you have, the higher your BMR will be.

You may be wondering... does my smartwatch give an accurate BMR? The short answer is no. Smartwatch trackers use movement, heart rate, and your height and weight to provide some calorie intel, but do not factor in muscle mass or body fat, both of which contribute to your BMR, says Cara Carmichael, CPT. “The number the watch is creating isn’t necessarily based on the individual,” she says. “It’s a more basic formula and there’s a lot of room for error.”

Even though smartwatches are not 100 percent accurate, they can give you a good starting point, adds Lombardi. But remember not to dwell on the numbers. Instead, take this information to understand your body and its necessary caloric intake.

BMR Versus RMR

Don't confuse your basal metabolic rate with your resting metabolic rate (RMR). They are similar but have a slight difference. “RMR is your BMR plus a very small level of daily activity such as walking to the bathroom, getting out of bed, and eating, but essentially being at rest,” notes Lombardi.

In practice, RMR is BMR plus baseline activity—so walking to your car, getting coffee, and climbing the steps to your house are all factored into RMR. On the other hand, BMR is literally just what your body burns naturally without any activity factored in.

Why BMR Is Useful Health Data

Beyond upping your knowledge (and appreciation!) for how your body works, knowing your BMR can help you reach your health and fitness goals. Here are a few benefits of your BMR:

  • Understanding caloric needs. Knowing your BMR can help you determine a nutrition plan and recognize your daily caloric needs, explains Carmichael. “A lot of us don’t truly know how much food we need to consume to get through the day without crashing, but your BMR can serve as a baseline,” she says. By knowing how many calories your body naturally burns, you can gauge how much you need to eat in order to gain (eat more calories than you burn), lose (eat fewer calories than you burn), or sustain weight (eat the same number of calories that you burn).

  • Weight management. Whether you are looking to lose or gain weight, understanding your BMR can help speed up the process by giving you necessary information to help set a diet that aligns with your goals, says Lombardi. Once you know your BMR you can use it as a base for the number of calories needed for the day. The higher your BMR, the more calories you can consume without gaining weight, she explains.

  • Tracking fitness progress. If your BMR increases, that generally means you are gaining more muscle and getting stronger, says Lombardi. Since gaining muscle is the most effective way to change your BMR, consistent strength training and tracking your BMR over time can be a great way to measure your progress and #gains.

  • Improving metabolism. A high BMR is often associated with a fast metabolism and greater muscle mass, while a low BMR can hint to a slower metabolism, lower muscle mass, and higher percent of body fat, says Carmichael. “A lot of people want to increase their metabolism, but you have to understand that in order to do that, you need to build more muscle and increase your BMR,” she says.

What is a good BMR number?

There isn't a "good" or "bad" BMR. “Each individual has a different BMR and cannot be compared to one another,” says Carmichael. What is considered to be “healthy” varies depending on the person and their goals. The average BMR for women is around 1400 kcal and about 1700 kcal for men, she says.

Even if you and your workout buddy are the same age, sex, height, weight, and body composition, you still can have different BMRs. Things totally out of your control, like genetics and even organ size, impact BMR.

Can you increase BMR?

Yes, you can increase your BMR. Incorporating strength training into your workout and gaining muscle mass is the most effective way to change and increase your BMR, says Carmichael. “Muscle uses a lot more energy than fat while at rest, so at any given weight, the more muscle on your body, the higher your BMR.”

Carmichael suggests incorporating strength training at least twice a week to build muscle and raise your BMR. But remember, consistency is key and change does not happen overnight. “So many people look for quick fixes, but in reality, it's about sustainability and sustainable habits.”

Changing your BMR can help boost your metabolism, lose weight, gain strength, or set an optimal meal plan, but there is not one magic number.

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