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Your metabolism is a complex system. It determines how quickly and
efficiently your body burns calories and how much you can eat in a day
without putting on weight. Scientists are still gaining new insight into
the factors that make your metabolism run. But they know for sure that
becoming a healthier, stronger woman can fire yours up—prolonging good
health, improving mood, slowing the effects of aging, and maybe even
helping you lose some weight along the way.
Experts share the latest findings, plus what you need to know to make all that good stuff happen.
Some parts of your metabolism are beyond your control.
Although many of us talk about “metabolism”
as if it’s a single bodily process, there are actually three types, each
of which expends energy (or calories) at a different rate. Your resting
metabolic rate determines the amount of energy your organs use to stay
functional when you’re just sitting around. It makes up the largest
piece of the metabolism pie (around 60 to 75 percent) on a regular
workday with minimal activity, and there’s very little you can do about
it. In fact, contrary to what you may have heard, thin people don’t have
faster resting metabolic rates. “The bigger you are—regardless of
whether that weight comes from muscle or fat—the higher your resting
metabolic rate will be,” says Martica Heaner, PhD, adjunct associate
professor of nutrition at Hunter College in New York City. Your active
metabolism—which accounts for about 10 to 15 percent of the calories you
burn in a day—dictates the energy you use up when you’re walking,
running, exercising, even fidgeting (for some people). This is the type
you have more control over, to some degree, since the more you move, the
more calories you burn. Finally, there’s diet-induced thermogenesis—the
energy your body uses to consume and digest food. Yep, you get a bonus
burn—8 to 12 percent of your daily calorie use—for eating!
TRY THIS TRICK: Believe it
or not, spicy food and green tea can fire up diet-induced thermogenesis a
bit. So brew some tea or pour a little hot sauce on dinner. “You’ll get
a teeny increase in your metabolic rate—we’re talking maybe a bump of 1
percent for an hour. But these little changes add up over time,” says
exercise physiologist Polly de Mille, clinical director of the Tisch
Sports Performance Center at the Hospital for Special Surgery in New
Your muscles are in charge.
A pound of muscle burns seven to 10 calories a
day, while a pound of fat burns just two or three. We all lose muscle
as we age, starting in our 20s, and as it vanishes, so does our
calorie-burning power. “By your 70s, your resting metabolism may be 15
percent slower than it was in your 20s,” says de Mille. “That’s 15
percent less food you can eat without gaining weight.” While building
new muscle can help counteract this trend, it’s even more important to
engage the muscle you already have, says Wayne L. Westcott, PhD,
professor of exercise science at Quincy College in Quincy,
Massachusetts. Every time you challenge your muscles by strength
training, they go through a breakdown-and-repair process, or remodeling.
This means you burn calories while working out and continue to burn
them after you put the weights away. Keep up the practice, and you’ll
increase the speed of your resting metabolism, even if your muscles stay
about the same size.
TRY THIS TRICK: Do two or
three 20-minute sessions of resistance training (12 to 20 sets of
exercises) each week. In three months, your resting metabolism will be
about 6 percent faster. When you exercise, focus on major muscle groups.
And don’t shy away from heavy weights. Start with one that’s about half
as heavy as the largest weight you can lift. As you become more
proficient, switch to weights that are 60 to 75 percent of your maximum
A lack of protein can slow your metabolism.
If you’re not already on the protein
bandwagon, get on board. Although the USDA suggests consuming 5 ounces
of a protein source per day as part of a 1,600-calorie diet, many
experts say that recommendation is conservative or even on the low side,
particularly for healthy adults over 50. Your body needs amino
acids—the building blocks of protein—to stay functional. “If you don’t
eat a diet rich enough in them, your body’s forced to tap your muscles,
which have a great reservoir,” says Wayne W. Campbell, PhD, professor of
nutrition science at Purdue University in West Lafayette, Indiana. When
you lose valuable muscle, your resting metabolism pays the price.
TRY THIS TRICK: Make sure
you’re putting protein in every meal and snack—starting the day with 15
grams (about two eggs) is a great idea. And don’t overlook whey, one of
two proteins found in milk. It’s rich in the amino acids muscles thirst
for and can aid recovery after workouts.
Dieting is the enemy.
Any weight-loss diet—yes, even one that seems
sensible—will leave your metabolism slower than it was when you weighed
more. That’s partly because each time you shed pounds, you lose fat and
muscle, but when you ditch your diet and regain weight, the pounds come
back as fat. And since smaller people have slower metabolisms than
bigger people, you’ll have to eat even fewer calories than you did at
the start of your diet to maintain your new weight. More annoying news:
The part of your brain that manages your metabolism cares little about
whether you ever fit back into your favorite jeans, and cares very much
about whether you have the energy you need to survive. Try to cheat your
body out of the calories it’s come to rely on, and it will immediately
start robbing your muscles of fuel and directing that energy to your
vital organs—causing your metabolism to dip lower.
TRY THIS TRICK: If your goal
is to lose a significant amount of weight, take it slow. “It’s best to
lose about 10 percent of your body weight, maintain that weight for
three to six months, then lose more if you desire,” says Laura J.
Kruskall, PhD, director of the UNLV Dietetic Internship & Nutrition
Center. “This gives your body time to adjust to physiological
adaptations, like a slower metabolism, and gives you time to learn
healthy weight-maintenance behaviors.” Also, never eat fewer calories
than your resting metabolism requires. The easiest way to determine that
magic number: Take your body weight in pounds and multiply by 10.
Your metabolism likes sleep.
A single night of sleep deprivation can alter
your metabolism and trigger weight gain, according to recent research
from Uppsala University in Sweden. Lack of sleep tends to slow people’s
metabolism, in part because that’s when your body repairs itself, which
burns calories, says de Mille.
TRY THIS TRICK: Debating
between an extra hour of sleep or working out? Do both! If you sleep in
and then squeeze in 10 minute bouts of strength training throughout your
day, you’ll give your metabolism an optimal shot at burning calories.