How to Calculate Metabolic Age? How Old are You Really?

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By calculating your metabolic age, you can gain insight into your body’s overall health and identify areas for improvement. In this article, we’ll explore the methods used to calculate metabolic age, including formulas and online calculators, and provide tips on how to interpret the results.

Whether you’re looking to optimize your health or simply curious about your body’s functional age, read on to learn more about how to calculate your metabolic age.

What Is Metabolic Age?

According to Catherine J. Andersen, PhD, RDN, associate professor in the Department of Nutritional Sciences at the University of Connecticut, metabolic age is most commonly defined as how your basal metabolic rate (BMR) compares to the average BMR for people your chronological age (how long you’ve been alive).

So what’s basal metabolic rate? That’s how many calories you need to sustain your basic vital functions while at rest without any external influences.

For example, it doesn’t take into account any extra energy you need to move or do physical activity, Andersen says.

This differs slightly from resting metabolic rate (RMR), which is the number of calories you burn outside of physical activity, according to the American Council on Exercise (ACE).

Why Is It Important?

Metabolic Age - why is it important

Understanding your metabolic age can be used to predict your physical health. According to a May 2017 study published in Transplantation, having a metabolic age lower than your chronological age signals good health, whereas having a greater one implies you may have some health problems.

“Those with more lean muscle tissue, better nutrition choices, and a more active lifestyle often have a lower metabolic age,” dietitian Lauren Minchen, MPH, RDN, tells

While additional research is needed, a small study of 19 persons published in Current Advances in Nutrition in June 2019 discovered a potential health benefit: having a metabolic age that is younger than your actual age was connected with reduced blood pressure.

And in Andersen’s lab, “we see an increased metabolic age associated with a higher BMI, waist circumference, body fat mass and blood pressure,” she says. “All of them are risk factors for heart disease, metabolic illness, and diabetes.”

Why Your Metabolic Age May Be Higher Than Your Actual Age

While chronological age refers to the number of years you’ve been alive, metabolic age is a measure of your body’s functional age.

It takes into account factors such as muscle mass, body fat percentage, and BMR to determine how efficiently your body is burning calories and maintaining its overall health.

A higher metabolic age than your actual age can indicate that your body is not functioning optimally, and you may be at a higher risk for health problems.

There are several factors that can contribute to it. One of the most common is a sedentary lifestyle, where you’re not getting enough physical activity on a regular basis. This can lead to a loss of muscle mass and a decrease in BMR, resulting in a higher metabolic age.

Poor nutrition, such as a diet high in processed foods and low in nutrients, can also contribute to a higher metabolic age.

Did you know that eating certain food can make your butt bigger?

Other factors that can contribute to increasing it include certain health conditions, such as hypothyroidism or insulin resistance, and medications that can affect BMR

Additionally, smoking, excessive alcohol consumption, and chronic stress can also contribute to a higher metabolic age.

If your metabolic age is higher than your actual age, there are several things you can do to improve it.

Incorporating regular exercise into your routine, particularly strength training exercises that build muscle mass, can help to increase your BMR and decrease your metabolic age.

Eating a balanced, nutrient-rich diet can also help to improve your body’s overall functioning and lower your metabolic age.

In some cases, addressing underlying health conditions or making changes to medications may be necessary to lower your metabolic age.

Quitting smoking, reducing alcohol consumption, and managing stress through techniques such as meditation or yoga can also have a positive impact on your metabolic age.

How to Improve

Healthy lifestyle factors can help lower your metabolic age.

Engage in Regular Physical Activity

Regular Physical Activity

Exercise is essential to improving your body’s overall functioning and decreasing your metabolic age.

Aim for at least 30 minutes of moderate-intensity exercise most days of the week, such as brisk walking, jogging, or strength training exercises.

Eat a Nutrient-Rich Diet

Eating a balanced, nutrient-rich diet can help to fuel your body and improve your metabolism.

Focus on consuming plenty of fruits, vegetables, whole grains, lean protein sources, and healthy fats while limiting processed and high-sugar foods.

Foods high in protein include:

  • Meat
  • Fish and seafood
  • Tofu
  • Eggs
  • Beans and lentils
  • Yogurt and cottage cheese


Eating too much protein can be harmful if you have certain medical conditions, such as kidney disease. If you’re unsure, talk to your doctor or a registered dietitian about what amount of protein is right for you.

Build Muscle Mass

Build Muscle Mass

Strength training exercises, such as weight lifting, can help to increase muscle mass, which can in turn increase your basal metabolic rate and decrease your metabolic age.

Reduce Stress

Chronic stress can negatively impact your metabolism and increase your risk of health problems.

Engage in stress-reducing activities such as meditation, yoga, or deep breathing exercises to lower your stress levels and improve your overall health.

Get Adequate Sleep

Lack of sleep can disrupt your body’s hormones and metabolism, leading to a higher metabolic age.

Aim for at least 7-8 hours of sleep per night to optimize your body’s functioning.

Quit Smoking

Quit Smoking

Smoking can negatively impact your metabolism and overall health, leading to a higher metabolic age.

Quitting smoking can have a positive impact on your health and decrease your metabolic age.

Consider a Plant-Based Diet

Eating a plant-based diet is associated with a lower metabolic age compared to chronological age, according to the ‌Current Developments in Nutrition‌ study.

Ready to change your eating habits? Get started with a seven-day plant-based meal plan.

Understanding Basal Metabolic Rate (BMR)

Your BMR is the bare minimum of calories required for your body to function at rest. As a result, it includes the calories you burn without ever lifting a finger.

Even when you’re sitting on the couch, you’re burning calories through processes like breathing, digestion, and blood circulation.

Physical activity is not taken into account in BMR. This is significant since 60 to 75 percent of the calories you burn each day occur while you appear to be doing nothing.

To calculate your BMR, you must consider your gender, height (in centimeters), weight (in kilograms), and age. You can use the Harris-Benedict Equation calculator or the following formula:

  • Male: 66.5 + (13.75 x kg) + (5.003 x cm) – (6.775 x age)
  • Female: 655.1 + (9.563 x kg) + (1.850 x cm) – (4.676 x age)

BMR is also known as resting metabolic rate (RMR).

A review of 2015.

According to a reliable source of scientific publications assessing RMR, there is no single RMR number that is appropriate for all adults.

These calculations may be complicated by body proportions and demographic factors.

The exact quantity of calories spent at rest is represented by resting energy expenditure (REE).

Fasting and indirect calorimetry are required to get at your REE. In this test, you have to lie down under a transparent dome. As you relax, a technician monitors your resting energy expenditure.

Though BMR and REE are calculated differently, the difference is less than 10 percent, so these terms may be used interchangeably.

Metabolic testing may be offered at health clubs and medical clinics.

How to Calculate Metabolic Age

How to Calculate Metabolic Age - Tips

Wondering how to find out your metabolic age? Well, there’s currently no standardized way to determine it, Andersen says.

Instead, various calculations and types of proprietary software are used. “I haven’t found any that have been truly validated by research,” she says.

That said, if you want to calculate your metabolic age, you need access to data of the metabolic age of other people who have the same chronological age as you, because you want to know how you stack up compared to them.

Only a few personal trainers, registered dietitians, and other professionals at medical or fitness centers have access to the technology that can estimate your metabolic age.

If you want to find out what yours is, look online for providers in your region or call around.

According to Andersen, these professionals may use bioelectrical impedance scales to measure your metabolic age.

You stand or hold onto sensors that deliver a low-level electrical current through your body, calculating metabolic age by measuring your body fat and lean body mass.

You can also find bioelectrical impedance scales online to buy for your home, but Andersen says these vary in accuracy.

With that said, if you have access to a metabolic age chart that shows you the BMR or RMR of other people in your chronological age group, you can calculate your own metabolic rate for comparison.

You can do that using several different equations:

1. The Mifflin-St. Jeor Equation

The Mifflin-St. Jeor equation to calculate BMR is derived from the Harris-Benedict formula, per a February 1990 announcement in ‌The American Journal of Clinical Nutrition‌.

  • For people assigned female at birth (AFAB):‌ (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161​
  • For people assigned male at birth (AMAB):‌ (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

Assume you’re AFAB, 30, 150 pounds (68 kg), and 5 feet tall (152.4 centimeters). You would have a BMR of 1,321.5.

As a reminder, that is an estimate of the calories your body burns when performing basic functions such as breathing and circulating blood, and does not include movement or any physical activity.


Manual calculations are not 100 percent accurate. Getting a completely accurate BMR calculation requires sophisticated equipment used in a highly controlled testing environment.

2. The Katch-McArdle Equation

According to ACE, this calculation uses lean body weight to compute BMR. You must know your body fat percentage to calculate your BMR using this formula, therefore if you don’t have it, continue with the Mifflin-St. Jeor calculation.

  • Lean body mass‌ = total body weight in kg – weight from body fat in kg
  • Katch-McArdle equation:‌ 370 + (21.6 x lean body mass in kg)

A 185-pound person with 10% body fat, for example, weighs around 84 kilograms, 75.5 kg of which is lean tissue. When you plug those numbers together, you get a BMR of roughly 2,000.8 calories per day.

3. The Cunningham Equation

If you’re not sure how to calculate RMR, the Cunningham equation can help.

It is utilized as an RMR formula because it employs lean body mass to produce a more accurate estimate of how many calories you burn each day than the Katch-McArdle equation.

According to a September 2013 study published in Issues in Clinical Nutrition, it may overstate your true RMR.

  • Cunningham Equation:‌ 500 + (22 x lean body mass in kg)

For the 185-pound person mentioned above, this equation puts RMR at 2,161 calories per day.


Good Bmr for My Age

What Is a Good Bmr for My Age?

Age Group Estimated BMR
20-29 1,356 calories
30-39 1,296 calories
40-49 1,251 calories
50-59 1,206 calories
60-69 1,161 calories

Is 1800 a Good Bmr?

Whether 1800 is a good BMR depends on several factors, including your age, gender, weight, and level of physical activity. BMR can vary widely from person to person, and there is no one-size-fits-all answer to what a “good” BMR is.

That being said, a BMR of 1800 calories is generally considered within the normal range for an adult female of average height and weight who engages in moderate physical activity. However, it’s important to remember that BMR is just one factor in determining daily caloric needs, and that physical activity level and other factors should also be taken into account.

What Happens to Your Bmr when You Don’t Eat Enough?

When you don’t eat enough, your BMR can decrease. This is because your body’s metabolism slows down in response to a reduced calorie intake, which can lead to a decrease in BMR.

When you eat less than your body needs, it enters a state of energy conservation and tries to preserve its energy stores by slowing down various bodily functions, including the metabolic rate. This means that your body burns fewer calories at rest, which can lead to a decrease in BMR.

How Do I Know if My Metabolism Is Damaged?

There are several signs that may indicate that your metabolism is damaged:

  1. Low energy levels or fatigue
  2. Slow healing
  3. Changes in weight or difficulty losing weight
  4. Digestive issues such as gas, bloating, constipation, or heartburn
  5. Mood swings or depression
  6. Food cravings
  7. Problems with skin such as eczema or psoriasis
  8. Inability to handle stress
  9. Feeling faint or dizzy

If you are experiencing several of these symptoms, it may be worth talking to a doctor or nutritionist to determine if there is an underlying issue with your metabolism.

Does Fasting Slow Metabolism?

Fasting can temporarily slow metabolism, but the effect is generally short-term and may be counteracted by other metabolic benefits of fasting.

During fasting, the body may enter a state of energy conservation and slow down various bodily functions, including the metabolic rate. This means that the body burns fewer calories at rest, which can lead to a temporary decrease in metabolism.

However, some studies suggest that fasting can also have metabolic benefits, such as improved insulin sensitivity and increased fat burning. These benefits may help counteract any temporary decrease in metabolism

Does Coffee Boost Metabolism?

Yes, coffee can boost metabolism due to its caffeine content. Caffeine is a stimulant that can increase metabolism by increasing the amount of energy your body burns at rest, also known as resting metabolic rate.

Studies have shown that caffeine can increase resting metabolic rate by up to 11% in some individuals, which can translate to burning more calories throughout the day. Additionally, caffeine can help increase fat burning by enhancing the breakdown of fat cells and releasing them into the bloodstream to be used as energy.

Bottom Line

Metabolic age is more of a fitness term than a medical one. It’s a way to compare your basal metabolic rate (BMR) to other people your age. It can offer a general idea of your metabolism so you can take steps to manage weight and improve health.

The best way to lose fat and gain lean muscle mass is to cut calories while increasing physical activity. If you have concerns about your BMR or weight, start by talking with your healthcare provider.