Weight loss jokes such as the one that goes, “I’m on a seafood diet. When I see food I eat it,” might give you a laugh but they won’t help you lose weight. After all as we age our metabolism slows down and that’s what causes those extra pounds. Right? Wrong! Researchers now tell us that metabolism, your body’s process of turning food into energy, doesn’t weaken with age, at least not until after you turn 60.

The Harvard Medical School defines metabolism as “the combination of all the chemical processes that allow an organism to sustain life.  For humans, this includes conversion of energy from food into energy for life-sustaining tasks such as breathing, circulating blood, building and repairing cells, digesting food, and eliminating waste.”

Herman Pontzer, Associate Professor of Evolutionary Anthropology at Duke University, conducted a wide-ranging study of individuals between the ages of eight days and 90-plus years old. His research team assessed how many calories the members of each age group burned, keeping track of how body size and age affected the rates of burn.  “We found that there are four distinct metabolic phases in life.  Zero to one years old, one to 20 years old, 20 to 60 years old and over 60 years old,” he says.  

Pontzer’s study revealed that while children have a very high metabolic rate, or Total Energy Expenditure [TEE], for their size. It found that the metabolic rate between the ages of 20 and 60 remains fairly steady and that it doesn’t slow down until we get to be about 60 years old or older.

The doctors at Harvard University, note that the Pontzer study “challenges previously held beliefs that metabolism correlates closely with organ-specific metabolic activity throughout growth and development, such that it is very high in infancy, childhood, and adolescence, and progressively declines throughout adulthood and old age. Instead, the authors observed that BMR [Basal Metabolic Rate] was 30% higher than would be expected based on body and organ composition in children 1 to 20 years old, and 20% lower than expected in adults 60 and above.  These deviations in expected TEE and BMR in childhood and old age support the notion that age-related metabolic changes may play a more important role than we previously gave them credit for.  What’s more, these results strongly suggest we may no longer be able to blame weight gain in middle age on a slowed metabolism.”

By John Grimaldi