What is metabolic age and what does it mean?
Metabolic age is not a medical term, rather a wellness concept that compares your basal metabolic rate (BMR) to the average BMR in your chronological age group. Recall that BMR is the number of calories your body requires daily at rest (think: the number of calories you burn just lying on the couch). Remember that you need energy (calories) for all types of bodily functions, including breathing, thinking, circulating blood, and so much more.
A higher BMR, commonly referred to as having a “fast metabolism,” is associated with a lower (healthier) metabolic age, and vice versa. A driving factor behind a higher BMR is muscle mass — the more muscle you have, the more calories and glucose your body burns, and the higher your metabolic rate is. Generally, increasing metabolic rate improves glucose regulation, which is one component of metabolic health. So metabolic age, even though it is not a medical term, can give insight into your metabolic health.
In fact, metabolic age was created with the aim of identifying those at risk for developing metabolic syndrome. (1) The basis for this metric is that adults lose muscle mass as they age, to the tune of 3-8% decrease per decade after the age of 30, and this rate of decline is even higher after the age of 60. (2)
Loss of muscle mass leads to a decrease in metabolic rate, which is unfavourable in part because muscle is the primary organ that processes glucose. With less muscle, your body has less machinery to handle the breakdown of carbs from your diet into glucose. That is why higher muscle mass and faster metabolic rate equate to a lower (better) metabolic age.
This article explains the concepts surrounding metabolic age, how to improve metabolic age (which ultimately means improving your metabolic health), and specifically how efficient your metabolism is. It all comes back to healthy glucose management.
How to determine your metabolic age
There isn’t a specific metabolic age test. Websites may claim to give you your metabolic age by inputting some personal information into an online calculator, but there is no universal test for metabolic age.
Calculating metabolic age takes two steps. The first is to determine your BMR (we explain how below). The second step is to compare your BMR to others in your age group. The exact equation that results in a metabolic age in years is proprietary (unknown).
How to calculate metabolic age:
Metabolic age = your BMR:BMR of population.
While determining your own BMR is a straightforward equation using your age, height, and weight (see below), databases that compile BMR by age are not publicly available. Companies that make bioimpedance scales can provide a metabolic age in their metrics because they compare your data to others in their database.
To calculate your BMR:
Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5.
Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161.
Can you lower your metabolic age?
Yes, increasing your BMR will decrease (improve) your metabolic age. A study that took metabolic age of individuals from a bioimpedance scale found that a metabolic age over 45.5 years, or a metabolic age more than 11.5 years older than the person’s chronological age, were indicators of high-risk for metabolic syndrome, (1) which includes high blood pressure, high blood sugar, too much body fat around the waist, and irregular cholesterol levels. This would suggest that lowering metabolic age is one way to lower risk for metabolic syndrome and improve metabolic health.
What are some steps I can take to improve my metabolic age?
- Strength train: A regular exercise routine improves muscle mass and the machinery in muscle that regulates glucose metabolism, all of which will increase your BMR, and subsequently improve your metabolic age. Aim to perform resistance exercises on two or more days a week that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders, and arms).
- Track body composition over time: If you don’t know your metabolic age, tracking your muscle mass is the next best thing. A simple bodyweight scale only tells you your body mass (your resistance against gravity). It's more useful to know what your mass is composed of; specifically, how much muscle do you have on your frame?
Some home scales may estimate this through bioimpedance, or you can have a body composition assessment done at a wellness clinic (such as with an InBody scan). Other methods to estimate muscle mass include skinfold thickness by a trained anthropometrist, ultrasound, air or water displacement, or dual-energy X-ray absorptiometry (DXA), which is primarily used to assess bone density, but can also read out muscle mass. While all methods vary in accuracy, what is most important is to pick one method and stick with it, that way you can clearly see changes over time. - Walk after meals: Consistently moving throughout the day keeps your metabolic rate up. Plus, moving specifically after meals steadies glucose. If you’re just sitting after you eat, glucose surges in your bloodstream and insulin is needed to move it into cells. Since there isn’t a huge need for energy at rest, glucose can be stored as fat. Instead of being sedentary after a meal, take a brisk walk. More glucose will be moved into cells with less insulin, and more glucose will be metabolized for energy, which keeps your metabolic rate up.
- Include protein with meals and snacks: Protein has the highest metabolic effect of all the macros. This means around 30% of the calories from protein are used for the digestion, absorption, and metabolism of what you’ve eaten, compared to only 5-10% for carbs and 0-3% for fat. (3) Your body has a daily need for amino acids, so be sure to have high-quality proteins like eggs, Greek yogurt, turkey, beef, chicken, cottage cheese, tofu, or protein powder with your all your meals to keep your metabolic fire burning.
A final note from Lingo
While you can’t reverse the true ageing process, you can improve your metabolism to be a bit healthier than the average person your age. This means increasing your metabolic rate and improving how well your body uses glucose. A product like Lingo, a biowearable that provides personalised glucose data and real-time coaching, can help you along your journey.