Are Tests that Measure Resting Metabolic Rate Accurate?

Are Tests that Measure Resting Metabolic Rate Accurate?

(Last Updated On: July 19, 2020)

measure resting metabolic rate

Have you ever wondered what your resting metabolic rate is? Some people are convinced that they can’t lose weight because they have a slow resting metabolic rate. If you’re curious, there are now centers that will test your resting metabolic rate. Some gyms even offer this service for a fee. You might wonder whether it’s worth the time and effort and if the results are likely to be accurate. Let’s take a closer look at metabolic testing and whether you can get accurate and meaningful information from this type of testing.

What is Resting Metabolic Rate?

Resting metabolic rate is often used interchangeably with basal metabolic rate, although the two have some differences. Let’s look at basal metabolic rate first. It is the minimum amount of energy your body must burn to stay alive. Even when you’re sleeping, your body requires a source of fuel. Compared to when you’re active, it’s quite low, but it takes energy to breathe, support organ function, and maintain body temperature.

Basal metabolic rate (BMR) accounts for as much as 80% of the calories you burn each day. People can have different basal metabolic rates because of variations in body composition, more muscle increases basal metabolism. Gender and genetics are also factors. Men have a higher basal metabolic rate than women, although that’s partially because they have greater muscle mass and muscle is more metabolically active.

Basal metabolic rate is difficult to measure, To get an accurate measurement, you must sleep at least 8 hours beforehand and fast for 12 hours. That’s why you need a controlled clinical setting for measurement and staff who knows how to measure BMR in an accurate way. Since basal metabolic rate requires controlled conditions with a standardized room temperature, it’s a more labor-intensive test and one that’s more time consuming and costly to measure.

As an alternative, sites measure resting metabolic rate instead. Resting metabolic rate is the energy your body uses when you’re resting. It’s a good proxy of your basal metabolic rate and is easier to measure with fewer limitations, like fasting for 12 hours beforehand. If you sign up at a site to get your resting metabolic rate measured, it will take about an hour. You must rest and wear a mask for 20 minutes to determine how much energy your body uses when you’re resting.

Resting Metabolic Rate Calculators

If you don’t mind getting a less accurate value, you can use an online resting metabolic rate calculator to estimate your resting metabolic rate. These calculators use the Harris-Benedict Equation estimate resting metabolic rate. The formulas look like this:

 

  • 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)

 

You only have to punch in your weight, height, age, and gender, to get a value. However, there are some limitations. These calculations overestimate your resting metabolic rate in obese people. As you can see, your height, weight, and age affect your resting metabolic rate. The heavier and taller you are, the more body mass your body has to work to maintain.

Age is important because resting metabolic rate declines by about 2.5% every 10 years after the age of 20, irrespective of gender. The average woman has a resting metabolic rate of around 1400 calories per day. For men, it’s closer to 1600 calories daily.

Can You Change Your Resting Metabolic Rate?

If you have a slow resting metabolic rate, can you increase it? Since resting metabolic rate is controlled by hormones, mainly hormones produced by your thyroid gland, it’s hard to change your resting metabolic rate through lifestyle alone. If you have a slow resting metabolism because of an underactive thyroid, thyroid supplementation will boost it, but that’s not an option if you have normal thyroid function.

Building more lean body mass through weight training can have a modest effect too by boosting metabolically active tissue. It’s also important to avoid starvation diets. Dieting can slow your resting metabolic rate since your body decelerates internal processes if you deprive it of energy.

You also get a bump up in metabolic rate after eating a meal because of the thermic effect of food. The increase is equal to around 10% of the calories you take in. Therefore, a bigger meal will boost your metabolic rate more. A meal high in protein also has a slightly greater effect on metabolic rate relative to eating carbohydrates or fat.

Exercise forces your body to use more energy too. Together, resting metabolism, physical activity, and the thermic effect comprise the total energy you burn each day, also known as total energy expenditure. However, your resting metabolic rate makes up the bulk of it, between 60 and 80%

Based on these findings, you’re limited in how much you can increase your resting metabolic rate, but you can burn more total calories through exercise, by not restricting calories, and by adding more protein to your diet.

The Bottom Line

Now you know what resting metabolic rate is, how it differs from basal metabolic rate, how you can measure it, and how much you can change it. Is it worth getting your resting metabolism measured? Knowing your resting metabolic rate probably won’t change things unless you believe your resting metabolism is slow because of an underactive thyroid. In that case, a thyroid function test will supply you with valuable information.

Knowing your resting metabolic rate is unlikely to change things since you can only modestly boost your resting metabolic rate by building more muscle and you should do that, anyway. If you want a rough estimate, use one of the online calculators to see where you stand, but don’t take the value as gospel, but it will give you an estimate.

 

References:

 

Fitness Prescription. February 2004. page 18.

Obes Res. 1997 Nov;5(6):622-31. doi: 10.1002/j.1550-8528.1997.tb00584.x.

Nutr Metab (Lond). 2004; 1: 5. Published online 2004 Aug 18. doi: 10.1186/1743-7075-1-5.

 

 

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