Metabolism May Not Decline With Age as Previously Thought

Many of us hold two tenets of weight loss as undisputed truths: It’s much harder to shed excess pounds or maintain a healthy weight as we age because our metabolism slows down, and women struggle with this more than men because of a naturally slower metabolism.

But a new study published in August 2021 in Science suggests that neither of these maxims are true. Metabolism, the rate at which the body burns energy, has long been thought to decline during middle age as people gradually lose muscle mass.

For the study, researchers assessed metabolism by measuring total energy expenditure, which includes energy burned at rest to perform basic functions like digesting food as well as energy burned during physical activity, using a process known as the doubly labeled water method. The method measures the amount of carbon dioxide people exhale during daily activities to determine how many calories they burn.

After collecting this data from 6,421 people ranging in age from 8 days to 95 years along with height, weight, and body fat percentage, researchers calculated average metabolic rates for men, women, and people in different age groups.