Does metabolism really slow down with age?

If you’re middle-aged and notice your midsection widening, you may think a sluggish metabolism is to blame.

A recent study released last year challenges that premise, though. For years, the assumption has been that your metabolism is slowing as you age.

But a study that included 6,500 people from 29 countries shows that metabolism for both men and women really doesn’t significantly drop off until you reach the age of 60. The age range of participants in the study ranged from as young as eight days to as old as 95 years.

“Geographic diversity can contribute to energy needs, and age is a known factor that affects body size, composition and tissue development, and for that reason it was important for researchers to use a large, diverse data set,” said Martha A. Belury, PhD, a professor of human nutrition in the Department of Human Sciences at The Ohio State University College of Education and Ecology. She was not involved in the study, which involved 80 researchers at various institutions.

“This study adds important evidence to the theory that energy requirements are driven by lean mass and body size. Evidence from this new study shows that energy requirements may also be driven by developmental periods, reflected by changes of tissues in development, growth, etc. that also add energy demands,” she said.

The bottom line: For most people, managing your weight is within your control. Building and maintaining lean mass is an especially promising method to manage body weight if you’re middle-aged or a post-menopausal woman. You can lose the weight.

“It means if we assume most of the weight gain or loss is in our control, it may change how people approach it. I have seen many people over the years ‘throw in the towel’ because they felt their metabolism was on the decline,” said Liz Weinandy, RD, a staff dietitian at The Ohio State University Wexner Medical Center. “It makes people feel like there is no use trying. This study may be the reminder we need that a healthy diet and staying active are important at all ages, and not just to control weight. Those are two major factors for overall health. It could be there are other factors we aren’t thinking about like how stress affects our hunger hormones. “

Those wishing to gain or lose weight should look at all potential factors, she said.

“That means even more so, we need to focus on eating well and being more active. We need to look at all the reasons a person may gain weight other than the presumed slowing of their metabolism. So many factors for weight gain are within our control and there are more than just what we eat and the activity we do,” Weinandy said. “This might get people thinking about their stress levels and how much sleep they get (or don’t get) and all the factors that lead to weight gain other than the presumed decrease in metabolism.”

Belury, who is also the vice president of the American Society for Nutrition, said the study makes the case for personalizing medicine. It builds on existing evidence that people need tailored nutrition, dietetics and medical care.

“A person weighing 132 pounds who is 18 years old will have different energy needs than a person weighing 132 pounds at 80 years of age. This means that needs for vitamins, minerals, required nutrients, calories and drugs will need to be ‘dosed’ based on age as well as body size,” Belury said. “For many of these items listed, age is the only thing that is used for ‘dosing determination.’ Both are clearly relevant.” Notably, though, both men and women had similar declines of energy needs after age 60, she said.

“If this study holds true over time, it shows that behaviors linked to weight gain are even more important since we know the metabolism variable is holding steady.”