The Two Types of Fat -- Visceral and Subcutaneous -- and Which Poses the Greatest Risk to You
by www.SixWise.com
It's the dreaded "F-word" -- FAT. Many of us are
consumed with it ... gaining it, fearing it and doing just
about anything to get rid of it. Yet we all have it. Even
lean adults have 40 billion fat cells; those who are obese
may have 80 billion to 120 billion. But it's not only the
amount of fat that makes the difference between being healthy
and unhealthy, it's the type of fat, and where it's distributed
in your body.
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People with large bellies are at a higher risk of dangerous
visceral fat, but thin people, particularly those who
lead sedentary lifestyles, are also at risk.
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Visceral Fat Vs. Subcutaneous Fat
There are two types of fat: subcutaneous and visceral. Subcutaneous
fat is the type found just underneath the skin, which may
cause dimpling and cellulite. Visceral fat, on the other hand,
is located in the abdomen and surrounding vital organs. It
can infiltrate the liver and other organs, streak through
your muscles and even strangle your heart; and you can have
it even if you appear to be thin.
It is the latter, visceral, fat that is linked to everything
from bad cholesterol and hypertension to diabetes, heart disease
and stroke.
While you can spot visceral fat if you have a protruding
"beer" belly, it's not always that simple. Only
a high-tech MRI (magnetic resonance imaging) can really show
the body's fat composition, and researchers are finding that
thin people may also have high amounts of this internal fat.
They've even developed a tongue-in-cheek name for them: Tofi
(Thin on the Outside, Fat on the Inside).
'"We've even scanned people who are underweight and
found up to seven liters of fat inside them," said Professor
Jimmy Bell, head of the molecular imaging group at the Medical
Research Council's center at Imperial College in the UK.
Looks Can be Deceiving
While commonsense would dictate that Japanese sumo wrestlers,
who eat upwards of 5,000 calories a day and are obese by most
weight standards, are setting themselves up for a barrage
of obesity-related health problems, studies have found that
this is not the case. Why? MRIs of sumo wrestlers have shown
they have hardly any internal fat.
"They have low cholesterol, they have low insulin resistance
and a low level of triglycerides," said Bell. "Their
fat is all stored under the skin, on the outside."
Meanwhile, someone who appears thin on the outside, yet doesn't
exercise nearly as much as a sumo wrestler, may be at risk
of a host of health problems because their fat is being stored
on the inside, and in the organs.
"This is particularly true of men who have a slim build
but who do little or no exercise," Bell said. "We
know now that 40 percent of people have fat infiltration of
the liver, which is linked to so many other health problems."
Is Fat Really an Organ?
While once considered an inert storage system, researchers
now know that fat cells are actually incredibly dynamic and
intelligent.
"They were always thought to be poor, dumb sacks of
lard," said Roger Unger, an obesity researcher at the
University of Texas Southwestern Medical Center. "It
turns out that they end up being very talented, very versatile,
very important players."
Fat cells not only produce chemicals and hormones but they
also send out signals that affect everything from our brain,
liver, muscles and immune system to our mood and ability to
reproduce.
"In the old days, people used to think fat tissue was
a passive organ," said Rexford S. Ahima, an endocrinologist
at the University of Pennsylvania. "Now it's obvious
that it makes and secretes more hormones and proteins than
probably any other. It's at the center of a very complex system.
It coordinates how much we eat, how much energy we burn, how
the immune system works, how we reproduce. The list goes on."
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Jogging 17 miles a week for eight months can produce
significant decreases in visceral fat, according to
a Duke University study.
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Do Genetics Play a Role in Visceral Fat?
Genetic factors do appear to play a role in fat storage and
body shape.
"Our work so far has shown that you can take two men
of the same age, with the same BMI [body mass index], and
find one with five liters of fat within him and another with
two liters," said Bell.
Body shape also affects a person's risk of carrying visceral
fat, with those shaped like apples (who carry weight around
their abdomen) at a higher risk than those shaped like pears
(who carry fat around their hips, thighs and bottom).
Want to Get Rid of Visceral Fat? (Crash Dieting is NOT
the Answer)
You may be tempted after reading this article to go
on a crash diet to lose visceral fat, but this is not
a wise choice. In fact, studies suggest that "yo-yo"
dieting (constantly losing, then regaining, weight) may encourage
visceral fat.
"Over the past five years, we've demonized fat and become
obsessed with obesity, which is mostly talked about in terms
of weight loss. But what matters is where it is distributed.
As you lose weight, it tends to go from the top and bottom
of your body first, so it can become concentrated in the abdomen.
That is the most dangerous zone of all, and it's possible
that going on a constant series of diets actually encourages
the storage of fat in this region."
What can you do to lose visceral fat? Exercise. A study by
Duke University Medical Center researchers found that people
who were physically inactive had significant increases in
visceral fat, while those who exercised frequently had significant
decreases in visceral fat, over an eight-month period. The
study found:
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Those who did not exercise had an 8.6 percent increase
in visceral fat.
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Those who exercised the highest amount (17 miles of jogging
per week) had an 8.1 percent decrease in visceral fat.
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Those who exercised a low amount (11 miles of jogging
each week) did not significantly increase or decrease
visceral fat.
"The results of our investigation show that in sedentary
overweight adults who continue to choose a sedentary lifestyle
the detrimental effects are worse and more rapid than we previously
thought," said Cris Slentz, Ph.D., who led the study.
"On the other hand, participants who exercised at a
level equivalent to 17 miles of jogging each week saw significant
declines in visceral fat, subcutaneous abdominal fat and total
abdominal fat," he said. "While this may seem like
a lot of exercise, our previously sedentary and overweight
subjects were quite capable of doing this amount."
"We also found that a modest exercise program equivalent
to a brisk 30-minute walk six times a week can prevent accumulation
of visceral fat, while even more exercise can actually reverse
the amount of visceral fat," Slentz said.
Recommended Reading
Those
Who Don't Diet are Better at Improving Health Than Those Who
Do Diet
The
7 (Honest) Facts You Should Know About Losing Thigh Fat, Gut
Fat, and Fat in Other "Problem" Areas
Sources
Guardian
Unlimited December 10, 2006
Duke
University Medical Center
Journal
of Applied Physiology, 2005 Oct;99(4):1613-8
Innovations
Report
WashingtonPost.com