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Fat is one of the most talked about, troublesome and baffling
components of the human body. However, in the last few years,
scientists, doctors and public health experts have learned a lot about
the elusive and somewhat misunderstood fat cell. Test your knowledge to
see if you're up to date.
Are fat cells simply a storage compartment for our gluttonous behavior?
No.
"Fat cells are the most important cells in the body. In fact, they are
the key reason that we've survived. If we didn't have fat cells, we
would probably be extinct," says Roger H. Unger, M.D., a diabetes
researcher at the University of Texas.
Fat is much more than an
oily storage compartment. "One of the biggest myths is that fat is
boring," says Evan Rosen, M.D., Ph.D., a professor at Harvard Medical
School. "We now know that fat is a major endocrine tissue, producing
hormones that regulate varied body processes -- like insulin
sensitivity, thyroid and immune function, clotting, blood pressure,
appetite and satiety and many others. This has been one of the great
revolutions in physiological thought of the last 10 years," adds Rosen.
Are there different types of fat?
While all fat is actually the
same, where it is stored makes a difference. There are two types:
subcutaneous and intra-abdominal. Subcutaneous fat is stored below the
skin (a traditional "pear"-shaped body). Intra-abdominal fat is behind
the stomach muscles and around the organs (an "apple"-shaped body).
Most women store fat subcutaneously in the breasts, hips, buttocks and
thighs, while most men store it in the abdomen, lower back, chest and
the nape of the neck.
Intra-abdominal fat is considered more
dangerous. "All of the potential health risks -- including diabetes,
hypertension and heart disease -- are related to intra-abdominal fat,"
says David Heber, M.D., Ph.D., professor of medicine and director of
the UCLA Center for Human Nutrition. Oh, and if you believe you can
simply get the fat sucked out using liposuction and instantly improve
your health -- think again. Research shows that liposuction may take
out subcutaneous fat, but it doesn't remove the dangerous
intra-abdominal fat.
True or False: We are born with a fixed number of fat cells, and that's all we'll ever have.
False.
According to Rosen, "Standard dogma was that we are born with all the
fat cells we'll ever have. This was probably based on the fact that
when early pathologists looked at samples of fat from obese people,
they saw bigger, but not more numerous cells." However, today most
experts agree that we can increase the number of fat cells.
According
to Samuel Klein, M.D., professor of medicine and nutrition at
Washington University School of Medicine in St. Louis, the most widely
accepted theory is that fat cells grow in size (up to about 1
microgram) and then, at some point, begin to recruit other cells to be
converted to fat. Fat also starts to accumulate in organs and other
tissues.
How many fat cells do we typically have if we are at a healthy weight? What if we're obese?
According
to Klein, individuals at healthy weights have about 40 billion fat
cells, while the very obese have about 100 billion. And the morbidly
obese could have as many as 300 billion.
Can you ever get rid of a fat cell once you have it?
Yes.
You can shrink fat cells by losing weight, and fat cells do die off
once they're not needed as storage depots, although scientists are
unsure how long that takes, says Christopher B. Newgard, Ph.D.,
professor of pharmacology and cancer biology at Duke University Medical
Center. However, it's much easier to add fat cells than to get rid of
them, says Klein.
Are you at a disadvantage if you have more fat cells than someone else?
Maybe. Although it has not been proved scientifically, diabetes
researcher Unger says it is plausible that once you lose weight and
have "empty" fat cells sitting around, they're just waiting to be
filled up. So once you develop additional fat cells on top of the ones
you've already been blessed with, they could be increasing your
appetite when you start restricting calories too much. Klein, however,
feels there is still limited evidence to support the notion that empty
fat cells "want" to be filled up.
True or False: Our bodies are programmed to defend against losing body fat.
True.
Long before we had supermarkets and easy access to highly palatable
food on virtually every corner, we were hunters and gatherers. Because
food availability was unpredictable, the body had to be prepared for
both feast and famine. The more we ate, the more fat we stored, and the
better prepared we were for times of famine because each excess pound
of fat provided us with additional days of life. In fact, our body
typically stores about 150,000 calories at any given time, says Klein.
This is what enables us to survive for months with just water.
When
we go on a diet, the body's ancient survival mechanisms kick in,
refusing to use up valuable stored fat, making it more difficult to
burn calories by lowering our metabolic rate and decreasing our energy
level and requirements. The body doesn't know if it's being starved
voluntarily (to lose weight) or involuntarily (because there's no
food). Fat was a valuable asset, and now it's become an albatross
around our waists.
True or False: People who are overweight are more likely to have a slower metabolism.
False.
"It's not accurate. In fact, the bigger a person gets, the more
calories they burn," says Klein. Your metabolic rate actually increases
as you gain weight -- it costs you more energy to move around. The
thing is, it doesn't increase enough to offset the extra calories and
prevent weight gain.
True or False: If you eat an extra 3,500
calories of food (meaning over and above what you burn in a day), you
will immediately gain a pound of fat.
Yes, technically, but...
"The storage of excess calories depends on the composition of those
calories and the time frame," says William T. Donahoo, M.D., professor
of endocrinology at the University of Vermont College of Medicine.
Because we eat meals that combine carbs, fats and proteins and are
constantly burning calories, it's hard to say exactly when and how much
of the food we eat will end up on our bodies.
If the extra 3,500
calories you consumed is all fat, about 75 to 85 percent will end up on
your body as fat, says Klein. Some will also end up as lean muscle
tissue and an increase in fluid accumulation. About 10 percent of the
food is used to actually process the excess calories. How soon will it
show on your body? An all-fat meal (versus all carbs or protein or a
combination) is the slowest to be absorbed, taking about four to six
hours.
Where does the fat go? In a perfect world, the fat
cells comprise the bulk of lipid storage -- exactly where it's supposed
to go. "However, when you're constantly overeating, the fat can get
stored in places it doesn't belong, such as the liver and muscles,
which can cause disease," says Philipp E. Scherer, Ph.D., a professor
of cell biology at Albert Einstein College of Medicine in New York City.
True or False: Muscle turns to fat without exercise.
False.
Muscle is muscle and fat is fat. You can't transform one into the
other. "Muscle atrophies -- that is, gets smaller -- and fat
accumulates, usually as a result of less activity and the same amount
of eating, which might give the appearance that muscle turns to fat,"
says John Acquaviva, Ph.D., professor of health and human performance
at Roanoke College.
CHARLES STUART PLATKIN JD MPH is a nutrition
and public health advocate, author of the best seller Breaking the
Pattern (Plume, 2005), Breaking the FAT Pattern (Plume, 2006) and
Lighten Up (Penguin USA/Razorbill, 2006) and founder of Integrated
Wellness Solutions. Copyright 2006 by Charles Stuart Platkin. Sign up
for the free The Diet Detective newsletter at www.dietdetective.com.
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