- Metabolic age is calculated using your basal metabolic rate (BMR) and average population values.
- It is not an officially recognised variable, and its calculation outside laboratory conditions is usually inaccurate.
- Metabolic age can be of telling value, especially in the long term.
What is metabolic age?
The concept of metabolic age is frequently mentioned online, and many facilities offer to calculate it. But what exactly does it mean?
Simply put, metabolic age determines how your basal metabolic rate (BMR) compares to the average BMR of a population with the same chronological age as yours. Although it's not an officially recognised metric, it gives an idea of how your body's metabolism stacks up against others in your age group. For example, even if you and a friend are both 40 years old (chronological age), your metabolic ages could differ depending on your respective BMRs. Does this sound confusing? The following sections will break down the concept in more detail.
What is basal metabolic rate?
Basal metabolism is the amount of energy your body needs each day to maintain normal functioning. This includes essential processes like brain activity, heart pumping, breathing, hormone secretion, and more. Simply put, BMR represents the energy that would be enough for you to survive if you were lying motionless in bed.
Several factors influence your BMR, including gender, age, body composition, and even the ambient temperature. When it comes to age, BMR does decrease as you get older, but not in the gradual way many people assume. Instead, the decline occurs in longer developmental stages. Metabolism is fastest between ages 1 and 20. After that, there’s a long plateau phase lasting until around age 60, meaning there isn’t much difference between the metabolism of a 30‑year‑old and a 50‑year‑old (assuming similar lifestyle and body composition). The next significant drop in BMR typically happens after age 60.
In reality, other factors come into play, such as decreased physical activity, loss of muscle mass, or an increase in body fat as you age. As a result, BMR tends to decrease by about 1‑2% every 10 years.
How is metabolic age calculated?
There are various formulas for calculating metabolic age — some use BMR values, while others consider factors like body composition, waist circumference, or blood pressure. Here arises a rather fundamental problem in the accuracy of the calculation: BMR can only be precisely measured under laboratory conditions, where strict guidelines must be followed to avoid distorting results. If you’ve decided to measure your metabolic age at a fitness centre using a "smart" scale or, at best, an InBody device that works on the principle of bioimpedance, you should take the results with a grain of salt.
The question of accurate measurement methods was also explored in a 2021 study by Hertel et al. In their research, the calculation was based on metabolite concentrations obtained from blood samples and nuclear magnetic resonance spectroscopy, which is usually only available in hospital or laboratory settings. Just to give you an idea, the equation used to calculate the metabolic age of the male respondents looked like this:
It’s clear that achieving the accuracy of study methods in non‑laboratory settings is nearly impossible, making the results of field calculations more approximate than precise.
Does this mean that metabolic age is useless?
While it might seem from the previous discussion that comparing your metabolic age to your chronological age offers little value, the opposite is true — to some extent. The metabolic age values you receive from commonly available sources are typically calculated using factors like body weight, height, chronological age, and body composition. The sum of these variables can help you assess your physical health since excess weight and body fat are linked to increased disease risk. Although individual measurements may not be entirely accurate, tracking your metabolic age over time can provide a useful indication of how your metabolism is functioning.
What does this look like in practice? Imagine you're 35 years old, and your metabolic age consistently comes out at 25. This suggests that your current lifestyle is well‑suited to maintaining a healthy metabolism. On the other hand, if your metabolic age repeatedly shows up as 50, it might be worth considering whether your regime needs changing. Once you've implemented appropriate adjustments, you can monitor whether your metabolic age decreases over time, giving you insight into the effectiveness of those changes.
4 simple tips to reduce your metabolic age
1. More exercise, more food
Exercise is one of the best ways to boost your metabolism. By increasing your energy expenditure, you can consume more food, keeping your metabolism running at full speed. Even the process of digesting food requires energy, and strict weight loss diets or starvation can cause the metabolism to 'freeze up' Besides, such diets are unsustainable, mentally taxing, and often dangerous.
What type of exercise is most effective? Focus on aerobic activities that are low in intensity but can be sustained for longer durations. Examples include brisk walking, running, cycling, swimming, and group classes like aerobics or Zumba. However, make sure you enjoy the activity and stay with it for a long time.
2. Strength training
In addition to aerobic exercise, it's important to incorporate strength training into your routine 2‑3 times a week. Strength training promotes the growth of muscle mass, which is crucial for your metabolic rate (the more muscles, the faster the metabolism). Additionally, intense strength workouts can trigger the EPOC effect (Excess Post‑Exercise Oxygen Consumption), which can increase your metabolic rate by 6‑15% for up to 24 hours after your
3. Maintaining optimal weight
As mentioned earlier, body composition is closely linked to metabolic rate. Excess weight and increased fat put a strain on the body, and the contribution of fat tissue to metabolic function is minimal. To maintain an optimal weight, ensure you're consuming the right amount of energy with a balanced intake of macro- and micronutrients. Also, stay hydrated by drinking water or unsweetened teas. Regular physical activity is, of course, a vital part of managing your weight effectively.
4. Sleep
In the area of normal metabolic function, sleep cannot be forgotten — its quality and sufficiency is crucial for the regeneration of all body systems. Lack of sleep not only saps your energy for exercise but also disrupts the balance of hormones in your body, leading to increased appetite and reduced muscle growth. In short, poor sleep can undo all your efforts to improve metabolic function.
Bottom line
Metabolic age compares the value of your basal metabolic rate to the average value in a population that falls into your chronological age category. However, the exact calculation of this value is inconsistent and very complex, so outside of laboratories and medical facilities, you will only get a rough estimate.
However, any type of information can be useful in assessing your health, especially over a longer period of time. With repeated measurements, you will know whether your lifestyle is in line with the principles important for your overall health or whether a change is required. Similarly, you can then monitor whether or not the measures you are taking are effective.
And how do you support the normal functioning of your metabolism? Pay particular attention to maintaining a normal weight, exercising, and getting quality sleep. The result will then be not only a more favourable number on paper, but you'll also feel the physical effects.
