From Consumer Reports, by Jeanine Detz, 1/12/2019

Do you find that, lately, you get full more quickly or your weight has started creeping up and you’re not sure why? A drop in your metabolism may be to blame. Metabolism is the rate at which your body uses energy or burns calories, and it’s dependent on a variety of factors. “It takes a certain amount of energy just to breathe, but your metabolism also includes your daily activities and all the chemical reactions going on in your body—everything from breaking down food to building cellular structures,” says Reyhan Westbrook, Ph.D., instructor of geriatrics and gerontology at the Johns Hopkins School of Medicine in Baltimore. Here are three factors that can slow your metabolism—and the steps you can take to keep it going strong. “The main reasons for the decline of metabolism are biological, but lifestyle also plays a major role,” says Zhaoping Li, M.D., Ph.D., a professor of medicine and director of the UCLA Center for Human Nutrition at the David Geffen School of Medicine. Muscle is a major calorie burner. But after age 30, muscle mass decreases approximately 3 to 8 percent per decade. Because muscle burns more calories than fat, that decline can significantly reduce the amount of energy your body needs. “People also tend to be less active as they age, which decreases their energy (calorie) output,” Westbrook says. But changes in muscle mass and physical activity are only part of the equation. Activity inside of your body’s cells also slows down with age, says Westbrook. Mental health. Anxiety can also put the brakes on your metabolism. A 2015 study published in the journal Bio­logical Psychiatry found that stress causes a decrease in calorie burning following a high-fat meal. “Since people tend to eat high-fat meals when they’re stressed, this could be a common occurrence,” says Janice Kiecolt-Glaser, Ph.D., director of the Institute for Behavioral Medicine Research at Ohio State University College of Medicine and the study’s lead researcher. Experts also suspect a link between depression and metabolism: “Depression has a direct impact on your appetite, food choices, and activity level,” Li says. Sleep. Getting enough sleep, and going to bed and waking up at consistent times, may help you burn fat more efficiently, Westbrook says. The National Sleep Foundation recommends that older adults get 7 to 8 hours of sleep per night, but health problems and medications often get in the way. Keeping Your Metabolism Up When faced with a slowing metabolism, your first instinct may be to eat less, but that can backfire. “When you restrict calories, you run the risk of not taking in enough protein, which can result in more muscle loss,” Li says. Even if you find that you get full more easily than you once did, it’s important to make sure you’re getting the nutrients you need. Focus on eating enough protein (the building block of muscle). The Dietary Reference Intake is 0.8 gram per kilogram of body weight (about 51 grams for a 140-pound person), but experts suggest that people ages 55 and older get a bit more. “Aim for at least 20 grams of protein per meal, or make 20 to 25 percent of every meal protein,” Li says. Try to include the nutrient every time you eat, rather than having all your protein in one sitting. Along with meat and seafood, eggs, cheese, nuts, and beans all provide ample amounts of protein. Building and preserving your muscle mass through strength training can also help keep your metabolism up. “Exercise like running and swimming promotes heart health, but resistance exercise preserves muscle mass,” Westbrook says. And research shows that your resting metabolic rate stays elevated by about 5 to 7 percent for up to 72 hours after a resistance session. Try a class at your local community center or YMCA, or check out the workouts on go4life.nia.nih.gov. Aim to do strength training at least twice a week. And don’t forget the importance of mental health and sleep: If you’re feeling persistent sadness or stress, talk to your doctor; to improve your sleep, exercise daily, stick to a consistent bedtime, and avoid alcohol and caffeine before bed.