One of the harsh truths of aging is that it’s easier to gain weight than it is to lose it. While it can feel like these extra pounds appear mysteriously, there’s actually a clear scientific explanation.
As we age, the number of calories we burn in a day slowly decreases. We enjoy our highest basal metabolic rate, or how much energy our bodies burns at rest, in our 20s. But over time, both men and women gradually lose muscle, and this decrease in muscle mass changes how many calories our bodies naturally burn. For women, this shift accelerates around age 40 with menopause, and can be impacted by individual genetics.
To understand how to prevent unwelcome weight gain, we called Dr. Kelly Pritchett, a spokesperson for the Academy of Nutrition and Dietetics. Here’s what you need to know.
How do our metabolisms change?
Typically, a one to two percent decrease in metabolic rate per decade is observed as we age. In addition, it’s common to see an increase in abdominal fat as well as visceral fat, which is the fat located around the vital organs.
Why does this happen?
This decrease corresponds to the loss of lean tissue that occurs with age. From age 25 to 50, this happens fairly slowly, with around 10 percent of muscle being lost. After 50, this process occurs more rapidly — an estimated loss of about 40 percent of muscle mass is lost from 50 to 80.
When does this happen for women?
It happens to both men and women as they age. Both men and women tend to see a loss of about one to two percent of muscle mass per year after the age of 50. With a decrease in muscle mass, we would expect to see a loss of muscular strength and endurance.
What can we do to offset the impacts of a change in metabolism?
Starting a resistance training program two to three times per week during early adulthood can delay this decline in muscle strength. And although the magnitude isn’t quite the same as strength training, participating in aerobic exercise three to five days per week would also be beneficial for preventing this decline. Furthermore, according to the World Health Organization, these benefits aren’t limited to an offset in muscle strength, but also a decreased risk for heart disease, mortality, type 2 diabetes, and various cancers.
How do you recommend women change their diet and exercise habits as they get older?
With this decrease in metabolic rate, calorie needs would also slightly decrease with age. Focus on consuming 25 to 30 grams of protein per meal rather than ‘back loading’ the protein at dinner, which is what most Americans do.