Metabolic age is a conditional indicator that compares the intensity of your basal metabolic rate (BMR) with the average value for different age groups. If your metabolism corresponds to a younger age, you are considered "metabolically" younger than your passport.
This is not a clinical diagnosis but a visual estimate from the world of fitness and bioimpedance scales. Nevertheless it echoes the idea of biological age and helps track the effect of lifestyle.
What metabolic age shows
The indicator reflects how much energy the body expends at rest relative to peers. The basal metabolic rate declines by about 1–2% per decade after age 20 — mainly because of the loss of lean (muscle) mass. The more muscle, the higher the BMR and the "younger" the metabolic age.
If the calculated metabolic age is below the calendar one, the metabolism works more efficiently than average; if higher, it is a reason to reconsider diet and activity.
How it is calculated
Most often the basal metabolic rate is first estimated using the Harris–Benedict or Mifflin–St Jeor formulas (which account for sex, age, height and weight), and then the result is compared with the average BMR for age groups. Bioimpedance scales do the same thing but also rely on the proportion of muscle and fat.
A second approach is estimation from lifestyle factors (activity, sleep, diet, waist circumference), without directly measuring metabolism. Both options give a guide rather than an exact "age figure."
Can it be influenced
Yes, and fairly predictably. Strength training builds muscle and raises the metabolic rate; regular activity, adequate sleep and control of visceral fat shift metabolic age downward. It is important to be honest: there are no strict clinical norms for "metabolic age," so it is better used as a tracker of change than as a diagnosis.
Calculate using this marker
Calculators where Metabolic age is used directly:
Frequently asked questions
Metabolic age higher than calendar age — is that dangerous?
By itself it is not a diagnosis. But a high metabolic age often points to low muscle mass, excess fat or low activity — factors worth correcting with diet and training.
How accurate are bioimpedance scales?
They give an approximate estimate: the result depends on hydration level, time of day and food. It is more useful to track the trend on the same scales than the absolute figure.