The Truth About When Your Metabolism Slows Down May Surprise You

I’ve heard many a middle-aged family member tell me their metabolism “just isn’t what it was in their 20s.” And while aging does usher in several changes, a new study published in the journal Science says changes in your energy expenditure (i.e., metabolism) may not happen as early as you’d think. 

To get the most accurate and comprehensive data on metabolism’s average peak and decline, researchers gathered various studies into one single database, called the IAEA Doubly Labelled Water (DLW) Database. Together, the researchers analyzed the daily energy expenditure of more than 6,600 people between 8 days and 95 years old. 

In order to figure out how many calories each participant burned in one day (doing vital activities like breathing, digesting, pumping blood, and everyday movement like using stairs, washing the dishes, fidgeting, etc.), researchers used a urine test method called “doubly labeled water,” which measures how quickly certain molecules are flushed out of the body. Based on the data they gathered, here’s what the researchers found.