How to work out your basal metabolic rate - and why it’s useful

We asked a fitness pro for his go-to formula

When it comes to weight management, your basal metabolic rate (BMR) can be a useful figure to have to hand. Reflecting the lowest limit of calories your body needs per day to perform various vital functions (such as breathing and digesting food), it provides an indicator of what’s needed to fuel your body’s basic needs at rest. “Our BMR is defined as the minimum number of calories required to live,” explains Head of Fitness at BXR London, Olu Adepitan. “It takes into account the number of calories our organs need to function while we are completely inactive. So imagine if you spent the whole day in bed laying in the same position, without eating.” Your BMR can represent anything between 40% and 70% of your body's daily energy requirements, depending on your lifestyle and age.

With this in mind, it can be helpful to bear in mind when it comes to embarking on a new exercise regime. “Knowing your BMR is useful for individuals wishing to reduce bodyweight, so that they can benchmark their calorie consumption,” says Olu. Factors such as height, weight, gender, age, genetics and muscle mass affect it. “The more muscle mass an individual has, the greater their BMR, as physiologically the body uses more energy to maintain more muscle," says Olu. "This means that when you have a lot of muscle mass, you'll burn more calories at rest.” As men usually have a higher level of muscle mass, they therefore tend to have higher BMRs than women.

Is it possible to calculate your BMR yourself? To a degree , yes. “It is important to know that it is impossible to know your exact BMR, unless it is measured via laboratory testing,” says Olu. As a starting point though, he does have a method for working out a rough estimate which we’ve detailed below for you. However, it is necessary to bear in mind that your BMR only forms one piece of the fitness puzzle - something that the trainers at BXR London convey to their clients during their complementary health assessments that accompany their one-to-one coaching packages. “One of the key components of the health assessment is using the inbody body composition analyser,” says Olu. “This piece of equipment is non-invasive and avoids painful pinches to the skin like calipers. It is a brilliant way to find out if your training program and nutrition is really working, or a good benchmark to start working from.” It looks to provide a comprehensive full segmental body composition analysis that includes the following:

• BMR

• Body fat mass, percentage and distribution

• Muscle mass, percentage and distribution

• Visceral fat rating

• Hydration levels

• Muscle imbalances between your left and right limbs

If you’re curious about your BMR now, here’s Olu’s guide for working it out.

A step-by-step guide for working out your BMR

There are two formulae used to calculate BMR, in [kcal / 24hrs] for men and women respectively:

For men:

1) Multiply your height (in cm) by 6.25

2) Multiply your weight (in kg) by 9.99

3) Add 1 and 2 together

4) Multiply your age by 4.92. Subtract this from the answer from 3 above

5) Add 5

i.e. BMR = (height (cm) x 6.25) + (weight (kg) x 9.99) - (age (years) x 4.92) + 5

For women:

1) Multiply your height (in cm) by 6.25

2) Multiply your weight (in kg) by 9.99

3) Add 1 and 2 together

4) Multiply your age by 4.92. Subtract this from the answer from 3 above

5) Subtract 161 from this

i.e. BMR = (height (cm) x 6.25) + (weight (kg) x 9.99) - (age (years) x 4.92) -161

BMR calculator example

For example, for a male whose height is 178 cm, weight is 78.6 kg and age is 37, he would use: (178 x 6.25) + (78.6 x 9.99) - (37 x 4.92) + 5 = 1,721 calories per day.

1112.50 + 785.214 - 182.04 + 5 = 1720.674

For a female whose height is 178 cm, weight is 78.6 kg and age is 33, she would use: (178 x 6.25) + (78.6 x 9.99) - (33 x 4.92) – 161 = 1,574 calories per day.

1112.50 + 785.214 - 162.36 - 161 = 1574.354