Lots of factors, beyond muscle and fat, can play into your metabolic age. This include hormones and gender, Moday says. Our BMRs are typically highest when we’re young, as we’re growing and developing, she says, but then it drops in your 20s and continues to do so after that.
Some studies do show a link between lower BMR and some health outcomes, including age-related mortality and diabetes. Also, metabolic age relates to your metabolic health, which is a strong indicator of overall well-being. Markers of metabolic health include things like waist circumference, blood sugar, triglyceride and cholesterol levels, and blood pressure (you can read more about that here.)
There is a downside to looking at BMR and metabolic age when it comes to your health, though—mainly, it’s nearly impossible to compare your personal BMR to others in your age group, because so many factors play a role in how many calories you burn at rest, Moday says. Your body frame and shape, your ethnicity, your genetics, can all play role.
Robin Forouton, RDN, a spokesperson for the Academy of Nutrition and Dietetics also says things like thyroid health, mitochondrial health, nutrient status, and metabolic flexibility (or how well your body transitions from a carbohydrate-burning metabolism to a fat/ketone burning metabolism) can also play a role in BMR.
In general, your goal should be to keep your BMR revving by living an overall healthy lifestyle. Moday recommends comparing your own personal numbers over time, rather than equating your body (or BMR) to other people’s. “When you look at BMR, 70% is due to height and weight and genetics—that leaves about 30% of variables you can control,” she explains. In other words: certain lifestyle choices may positively affect metabolic age.
Fitzgerald recently released a small pilot study with her team that found that following an 8-week program that included a sleep, nutrition, and exercise component, along with relaxation techniques and supplements reduce participants’ biological age by three years—showing while you can’t stop your chronological age, you can impact what’s happening internally.