Sometime around age 40 or 45, you wake up and find yourself facing a labor problem: Your metabolism has staged a work slowdown. Whereas once it incinerated calories with the ferocity of an eight-burner Viking range, it now warms them with the timidity of an egg poacher. You’ve had to go up a jeans size or two . . . or three. If you’re a practiced dieter, you may turn to the weight-loss methods that have been so reliable in the past—and discover they no longer work.
Though this metabolic slowdown takes most of us by surprise, it has been developing for many years. Our metabolic rate—the total number of calories the body burns every day—dips 2 to 4 percent a decade starting in ourtwenties, says David Heber, MD, PhD, director of the UCLA Center for Human Nutrition. The cause of this decline is a shift in our body’s muscle-flab ratio. Every 10 years we lose five to seven pounds of muscle, which is replaced by fat, and this exchange continues for the rest of our lives. In metabolic terms, lean tissue is a champ, and fat is a -slacker: A pound of fat burns a mere three calories an hour, while muscle burns 14.
Say you’re a moderately active woman who burned 2,000 calories a day when you were 25. Keep exercising and eating exactly the same way, and you’ll burn 1,900 calories a day at 35. At 45, you’ll burn only 1,800.
And it gets worse. The loss in muscle mass accelerates when we approach menopause, and our levels of sex hormones like estrogen and progesterone drop. Wendy Kohrt, PhD, founder of the Image Research Group (Investigations in Metabolism, Aging, Gender, and Exercise) at the University of Colorado, found that our metabolic rate is highest when estrogen and progesterone are at their peak. When these hormones dip, we require about 70 fewer calories a day to maintain body weight. Jennifer Lovejoy, PhD, a researcher in Seattle who studied how body composition changes during menopause, estimates that over the roughly 10-year period of perimenopause and menopause, about 50 percent of women gain 10 to 15 pounds because of a lowered metabolic rate.
The bottom line: If you’ve gained weight and you’re thinking, “It’s not me; it’s my metabolism,” you could be right. However, with some tweaks to your diet and exercise regimen, you can get your metabolism to hum the way it did when you had a shag haircut and were living in your first apartment.
To effectively rev up your metabolism, you need to understand the components. Basal metabolic rate, or BMR (also called resting metabolic rate, or RMR), accounts for 60 to 75 percent ofdaily calorie expenditure. Sit still all day and your body will burn up this chunk of energy through activities like pumping blood, breathing and maintaining body temperature. An additional10 percent of your daily calories are spent on digesting food. The balance of your calorie tally—15 to 30 percent—is expended through movement, from tapping your feet as you listen to Pink to training for a half-marathon.
Your goal is to increase the number of calories burned in each of these areas. To do that, you need to eat and work out smarter, which will mean something different for each of us. Here, the stories of four women who took different paths to boosting their metabolism. You can try whichever strategies best suit your lifestyle and athletic abilities. Ladies, start your engines!
Rita Tretter's Secret: Constant Movement
Used to weigh: 169 lb.
Now weighs: 133 lb.