When you talk about aging with any regularity, you’ll start becoming familiar with all the different numbers and ages that the experts use to track your health. Chronological age, biological age… they’re not complicated concepts, but there do seem to be a lot of them. Metabolic age is just one more calculation for the pile (https://longevity.technology/lifestyle/metabolic-age-test-what-it-is-and-how-it-impacts-your-health/).
So, as a reminder, chronological age is your literal age in years, calculated from your birthday. Biological age is how old your body is depending on a range of different biomarkers. Metabolic age is about how we turn food into energy and then use that energy. More specifically, it involves what’s known as your basal metabolic rate (BMR) when compared to other people of the same chronological age. BMR is the speed at which you expend energy while your body is at rest.
There are lots of things that influence your metabolic age, and some are more changeable than others. Your genes, for example, are things you inherit whether you want them or not. Diet and exercise are pretty much all up to you. Then there are things where your body has a natural inclination but you may be able to modify it, like your hormone levels (particularly thyroid hormones or insulin) or muscle mass (muscle burns more calories than fat, even at rest). Other lifestyle factors include sleep habits and stress levels.
Why is this important? A lower metabolic age relative to your chronological age implies your body is running more efficiently. If your metabolic age is high, that could indicate underlying issues with your hormones, nutrient absorption or energy conversion. You may need to make some modifications to your diet or exercise habits. It may also indicate an increased risk of developing chronic conditions like cardiovascular disease.
Of course, first you need to calculate your metabolic age. The most effective way is a method known as indirect calorimetry, where you breathe into a special mask or mouthpiece so your oxygen consumption and production of carbon dioxide can be measured. There are several formulas used to calculate BMR, including Harris-Benedict and Mifflin-St Jeor, both of which work slightly differently for men and women. Your data is then compared to the average BMR for different age groups to provide your metabolic age.
Knowing your metabolic age may allow you to better tailor your personal health goals.
