in this post i will explain about
Rev It Up: How to Reboot Your Metabolism
What Affects Your Metabolism
I am lying on what looks like a cross between a jumbo Xerox machine
and a tanning bed at the University of California, Los Angeles, Risk
Factor Obesity Program as the big mechanical arm of a DEXA (dual energy
X-ray absorptiometry) scanner moves over my head and then down to my
feet. I came here to get the latest high-tech body-composition tests and
to learn how fast my metabolism is.
Two minutes later a virtual relief map of the muscle, fat, and bone in my body starts to fill in on a computer screen.
"I never would've guessed," says Zhaoping Li, MD, PhD, the UCLA
professor of clinical medicine analyzing my results, when she reads me
the verdict: 40 percent body fat. As in obese. Except I'm a size 8. Here
in Los Angeles, that alone can make you a plus size, but at five feet
four inches and 148 pounds, I'm really just three or four pounds
overweight.
To think that I had actually been looking forward to this visit. Me,
the lucky girl who never dieted, never gained the freshman 15 and, until
recently, never came close to being overweight. I chalked it all up to
my speedy metabolism.
Electrodes are pasted onto my hands and feet for my second test, the
bioelectrical impedance analysis. This one pegs my body fat at 32.7
percent, which, I am assured, is the better figure to go with.
Translation: I'm not obese, just borderline unhealthy.
I am what is called skinny fat, explains David Heber, MD, PhD,
director of the UCLA Center for Human Nutrition, who oversees the
obesity program. "People can appear to be thin and fit, but their body
fat is putting them at risk for diabetes, heart disease, and even breast
cancer," Dr. Heber says. "A lot of models and actresses who don't
exercise are actually skinny fat."
For the next eight weeks I would systematically follow the advice of
leading scientists and trainers to reboot my metabolism. What I found
out may be the key to keeping yours from ever flatlining.
What Affects Your Metabolism
I'm living proof that you can't judge a metabolism by its cover. You
and I could be the same height and weight, have the same BMI, and even
fit into the same J Brand jeans, but have wildly different
flab-to-muscle proportions, making one of us the calorie-burning
equivalent of a Bic lighter and the other of a blowtorch.
Metabolism, simply put, is the total number of calories your body
burns each day. Sixty-five percent of those calories are used up for
24-7 functions like breathing and circulation — the top burners are
your brain, liver, heart, and kidneys — with another 10 percent devoted
to the process of digesting the very foods that may have given you that
muffin top in the first place. The remaining 25 percent of the calories
you burn can be chalked up to the physical activity you do in a day —
not just Spinning class but every move you make, including standing in
line or tweeting your latest DEXA scan results.
You've heard it before: The more muscle you have, the more calories
you burn. In fact, lean tissues, including organs and muscles, on
average burn 14 calories a pound a day, while fat only burns about three
calories per pound, Dr. Heber says.
Simply put, whether you're Kate Moss or Kirstie Alley, it's the
absolute amount of muscle in you that determines the overall speed of
your resting metabolism — the amount you burn just sitting around — and
some of us are born with an edge in the amount of muscle fibers we've
got. But don't blame bad genes for your extra flab. "It's your
environment — that is, food and activity — that is extremely important
in ultimately determining your weight," says Andrew G. Swick, PhD,
director of obesity and eating disorders research at the University of
North Carolina at Chapel Hill Nutrition Research Institute in
Kannapolis.
And there's plenty you can do to not only add muscle but also maximize your metabolism along the way.
Workouts and Diets for a Faster Metabolism
Workouts for a Faster Metabolism
Metabolism slows over time, but it doesn't do a sudden nosedive as you sit watching the
American Idol
finale. "Metabolism drops off 2 to 4 percent every decade as we tend to
lose muscle mass," Dr. Heber explains. So, if as a twentysomething you
burned 2,000 calories a day, fast-forward 10 years to your midthirties
and you could be burning as few as 1,920 calories a day. Doesn't seem
like a big difference until you do the math. Just 80 extra calories a
day translates into eight pounds over a year, unless you pick up the
slack with exercise.
"You can maintain your total energy expenditure as you age by
combining strength training and aerobic activity. You'll probably need
to do more of both," says Miriam Nelson, PhD, director of the John
Hancock Research Center on Physical Activity, Nutrition, and Obesity
Prevention at Tufts University in Boston. Nelson's studies in the 1990s
found that a twice-weekly regimen of eight to 12 resistance exercises
increased women's strength by 75 percent in one year, meaning they
gained more metabolism-stoking muscle fibers. Most of those gains were
in the first 12 weeks.
Even better, every workout you do will give you a metabolism boost,
not just during it but also afterward. One study found that a 50-minute
weight routine delivered an additional afterburn of 14 calories. Between
sets, add cardio bursts or shorten the rest, and that afterburn spikes —
to the tune of 25 calories following a quickie 19-minute circuit
session, according to the same study.
I tested this myself by wearing a Bodybugg device on my right biceps
as I followed the FITNESS "Your Best Body Ever" with trainers Justin
Ghadery and Jeff Peel at 24 Hour Fitness in West Hollywood. The device's
sensors track not only your movements but also things like body
temperature to continuously record the number of calories burned during
the day. The highest calorie-burn days occurred when I did the
total-body circuits with Peel versus any other time I went to the gym.
I saw similar afterburn increases when I added speedier bursts to my
steady treadmill workouts. Scientists have measured afterburn for a
half-hour jog at 35 calories, as opposed to 75 calories for 20
one-minute sprints (with two-minute rests in between).
Not only that, but "high-intensity interval training is a quick way
to ramp up your body's ability to use fat as a fuel," explains Jason L.
Talanian, PhD, assistant physiology professor at Fitchburg State
University in Massachusetts. In a study Talanian conducted, women who
did interval workouts on a stationary bike, similar to Spinning, burned
36 percent more fat when they switched back to a steady ride the
following week. The speed bursts sparked a 20 percent increase in the
amount of mitochondria in the exerciser's muscle cells, making it easier
for the women to metabolize fat for fuel rather than carbs.
To net the afterburn uptick, "push your speed for 30 seconds when you
walk or run, and then return to your usual pace for 30 seconds," Peel
says. Over the course of a month Peel has me increase the ratio so I get
30 seconds of slowdown time for every minute of intense exercise.
What to Eat for a Faster Metabolism
Having a lab test indicate you're made out of jelly could send a girl
off on a juice-cleanse bender, but that would actually slow your
metabolism. "If you're on a very low-cal regimen — in the 400- to
800-calorie-a-day range — metabolism falls by 15 to 20 percent," says
David Nieman, PhD, professor of exercise science and director of the
Human Performance Laboratory at Appalachian State University in Boone,
North Carolina. Eating less than 900 calories a day also prompts your
body to burn muscle tissue as well as fat, which lowers your metabolic
rate even more.
Stick with the 1,200- to 1,500-calorie a day range, Nieman suggests,
and you'll still slim down without taking such a big bite out of your
metabolism. "What's more, about 90 percent of the weight you lose will
be fat," he says, sparing more of that calorie-burning muscle.
Another metabolism no-no that women are guilty of is ditching meals,
Neiman says. "If you skip meals, you put yourself on that path toward
fasting, which signals the metabolism to slow way down," he explains.
Meanwhile, Dr. Heber warns me to get more protein to help preserve
the lean mass that's my metabolism workhorse. He recommends the higher
end for me: 100 grams of protein a day from such foods as white meats,
fish, egg whites, and soy, starting with breakfast. "Studies show that
people who eat a high-protein breakfast control their hunger longer and
their weight better," says Dr. Heber, who is the author of sensible diet
books, including
What Color Is Your Diet? I promptly replace my cornflake habit with egg-white omelets and the occasional whey-powder-injected pancakes.
"Think
of your body as a Ferrari," says trainer Ghadery when I tell him I've
turned over a new leaf with protein. "You don't put cheap gas in a
vehicle like that."
Measure Your Metabolism
Four weeks after my initial visit to the UCLA lab, I'm 10 pounds
lighter, but more important is that my total body fat has dropped 5
percent, according to the DEXA scan. "We don't usually see any
significant change in body composition until at least eight weeks," Dr.
Li says, so the workout is working.
At my final appointment at eight weeks, I almost fist-bump Dr. Li
when she tells me that of the 14 pounds total that I lost, nearly 10 of
them were pure fat. "That is a lot," she says. But here's the kicker:
Those other four pounds were a combination of water weight and muscle,
meaning my resting metabolic rate went down from 1,150 calories a day to
1,117 calories a day.
"Normally when people
lose weight
that is muscle, their metabolism goes down; it's one of the factors
that causes them to gain weight back," Dr. Heber explains. "By
exercising, you maintained 97 percent of your resting metabolism. If you
hadn't exercised, you would have lost 20 pounds, but up to half would
have been lean mass."
Back at the University of North Carolina, Swick and other scientists
are homing in on identifying the different genes responsible for energy
expenditure, as well as phenotypes of people who don't gain weight from
overeating, in the hopes of identifying the variables that make us fit
as opposed to fat.
So the blueprint for a perfect metabolism is in the works, but I
won't be sitting around for it. I've already learned my lesson: No more
running low on muscle.
Do the Math on Your Metabolism
For a ballpark figure of how many calories you burn a day, multiply your weight by 14.
Use our BMR Calculator to get a closer estimate that also factors in your activity level
Measure Your Body Composition
Hitting the right weight is great, but also aim for a healthy body
fat percentage to make sure there's some muscle to your metabolism.
| Body Fat Percentage |
|---|
| Age |
Healthy |
Overweight |
Obese |
|---|
| 20-39 |
21-32% |
33-38% |
≥39% |
|---|
| 40-59 |
23-33% |
34-39% |
≥40% |
|---|
| 60-79 |
24-35% |
36-41% |
≥42% |
|---|
Body Fat Measuring Tools, Tested
Check out how real-world body fat tests rate.
Body Fat Scales
These home scales, like ones by Tanita ($50 and up,
amazon.com),
use bioelectrical impedance analysis, but unlike instruments in a lab,
they send currents through only the lower body rather than chest to toe.
Still, they're a good measure of the change in readings between
weigh-ins.
Skin-Fold Test
A caliper, or pinch device, measures the thickness of folds of skin in
four key places where you store fat: the triceps, the suprailiacs (near
the hip bones), the abs, and the thighs. Your best bet is to get two
readings from a pro at the gym and take the average.
Bod Pod
As you sit inside the photo-booth-size Bod Pod for a few minutes, air
displacement measures your body composition. Such clubs as Gold's Gym
now use this device to get more accurate readings than with skin-fold
tests.
"Why Can't I Lose Weight?"
If you've ever blamed a slow metabolism for your weight woes, we may be about to crack the code on the real culprit.
FITNESS sent 35-year-old broadcast media consultant Hillary Locke to
the cutting-edge New York Obesity Research Center in New York City.
There she spent all day and night in an airtight chamber as a scientist
watched every move she made and morsel she ate to determine why this gym
devotee and serial dieter couldn't seem to lose an ounce.
The result: Hillary's metabolism is not in fact slow but humming. She
burned an impressive 2,397 calories in 24 hours — 540 during 60 minutes
of riding the stationary bike and 30 minutes of toning exercises. She
even lost a little more than a pound overnight!
So what gives with Hillary's three-year weight plateau?
The red flag was that she was burning mostly carbohydrates, even in
her sleep, says Russell Rising, PhD, a nutrition researcher at the
center. "The ratio of fat versus carbohydrates you burn should typically
decrease during sleep to the point where you're burning more fat,"
Rising says. But readings of the carbon dioxide content in Hillary's
breath, taken at night, indicated she was burning more carbs instead of
fat.
Sure enough, Rising found that Hillary's diet while she was in the
lab was 48 percent carbs, 41.8 percent fat, and 11 percent protein. He
surmises that Hillary also probably eats a lot more a day than the 1,383
calories she ate in the lab and that her hectic travel schedule
disrupts her sleep and, therefore, circadian rhythm, in turn affecting
her ability to
burn fat.
Hillary's next stop was to meet with Marissa Lippert, RD, the owner
of Nourish Nutrition Counseling and Communications in New York City.
Lippert advised Hillary to reduce her stress eating and make simple
changes, like trading airplane pretzels for yogurt and limiting wine to
one glass.
Within a week Hillary dropped three pounds.
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