Noticing lately that your normal diet and exercise routine no longer keep you from putting on those extra pounds? You’re not imagining things. Studies show that your metabolic rate declines by one to three percent per decade after you hit 30, notes Carmen Roberts, a registered dietitian specializing in weight management at Johns Hopkins Bayview Medical Center.
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It can make you feel like you’re wasting your time hitting the treadmill and saying no to sweets, but don’t give up. You can regain some control over your body’s slowing metabolism by understanding why it happens and what you can do about it.
Why metabolism slows with age
First, the good news: Most scientists agree that old muscle still burns as many calories as young muscle. But the bad news? Muscle loss is an inevitable part of aging, says the Mayo Clinic’s James Kirkland, M.D., Ph.D.
“There are progenitor cells within your muscle tissues that give rise to new cells,” Dr. Kirkland explains. As you age, these re-builder cells become less capable of replacing expired muscle cells, so your overall muscle mass decreases.
Muscle tissue burns most of your calories. A decrease in muscle mass means your body needs fewer calories to operate, so that afternoon snack you used to count on becomes excess calories stored as fat. As you age the energy factories in your cells, called mitochondria, also slow down. Some researchers think that this lower use of energy by mitochondria could also result in fewer calories burned by your body.
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What you can do about it
“The main thing,” says Roberts, “is to fight against losing your muscle mass by engaging in weight-bearing exercises on a regular basis.”
That includes walking, Roberts explains. “But if you want to better target your work-outs to muscle building and retention, what would be more effective would be weight training or strength training,” she says.
With regular aerobic and strength training routines, it’s possible to maintain and even increase your muscle mass. For those just starting out with exercises, “results can be seen in as little as two 30-minute strength training sessions per week,” Roberts points out.
As far as diet, she has some relieving advice: Don’t go overboard on calorie restriction. If you’re not eating enough, you risk both over-limiting your protein consumption and also slowing your metabolism to a snail’s pace.
“You want to make sure you’re eating adequate protein—half of a gram per pound of body weight,” notes Roberts. “So a 150-pound woman needs approximately 75 grams of protein per day.” That’s as much protein as a dozen eggs. Luckily, you don’t have to eat your weight in eggs. Instead, Roberts recommends several lean protein options:
- low-fat animal sources (chicken, fish, lean beef and pork)
- dairy products (fat-free or low-fat milk and cheese)
- soy products (tofu, soy milk)
- nuts (including nut products such as almond milk)
You want your body to fuel itself by burning up your fat stores. If you aren’t getting enough protein, your body will start breaking down muscle instead—the last thing you want when you’re already fighting age-related muscle loss.
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Roberts also recommends making sure you’re eating often. Three or four times a days isn’t enough. “When we go too long between meals,” she explains, “the metabolic rate slows down and conserves until you eat again.” That means your body burns fewer calories (and fat) than normal because it’s preparing itself for starvation.
The bottom line: Muscle loss and a slowing metabolism is an inevitable part of the aging process. But you can take steps to mitigate weight gain, improve your health, prevent injuries and extend the quality of your life.