Leptin: What It Is, and Why It May Be the Most Powerful Tool in the Battle Against Diabetes
by www.SixWise.com
It's well known that obesity and diabetes often go hand-in-hand.
Over 60 million Americans are obese, a condition that makes
it 20 to 40 times more likely that you'll develop diabetes
than someone of a healthy weight, according to the Harvard
School of Public Health. Even being overweight (as opposed
to obese) increases your risk of type 2 diabetes seven-fold.
Still, while epidemic numbers of Americans--nearly 20 million--have
diabetes, it is not known why some obese people develop diabetes,
while others never do.
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Some leptin research suggests that the tendency to
overeat and gain weight may be formed at an early age.
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A Hormone Called Leptin
The protein hormone leptin--which comes from the Greek word
for "thin," leptos--may hold the key to unlocking
some of this mystery. Derived from fat cells, defects in leptin
signaling may lead to obesity, overeating and less energy
expenditure.
According to metabolic specialist Ron Rosedale, M.D.:
"Leptin is the way that your fat stores speak to your
brain to let your brain know how much energy is available
and, very importantly, what to do with it. Studies have
shown that leptin plays significant, if not primary, roles
in heart disease, obesity, diabetes, osteoporosis, autoimmune
diseases, reproductive disorders, and perhaps the rate of
aging itself."
Further, a study on mice published in Cell Metabolism has
revealed that leptin plays a role in regulating blood sugar,
which it does via two brain-body pathways:
If the first pathway (the one involving appetite and fat
storage) is disrupted, obesity is expected, which raises the
risk of diabetes. However, the study found that both pathways
may have to be disrupted in order for the body to lose control
of insulin and blood sugar levels and develop diabetes.
"Taken together, our findings show there's more to the
obesity-diabetes link than the classic thinking that if you
eat too much sugar, you'll get fat and get diabetes and that
if you don't get diabetes, it's only because you're making
more insulin to keep up with the sugar," says senior
author Martin G. Myers, Jr., M.D., Ph.D., of the University
of Michigan Medical School. "There's something else contributing.
Now the challenge is to find out what that is."
Leptin's Link to Fat and Diabetes
"If a person is getting too fat, the extra fat produces
more leptin, which is supposed to tell an area of the brain
in the hypothalamus that there is too much fat stored, more
should not be stored, and the excess burned," Rosedale
says.
"Therefore, signals are sent to stop being hungry, to
stop eating, to stop storing fat and to start burning some
extra fat off. More recently, it has been found that leptin
not only changes brain chemistry, but can also "rewire"
these very important areas of the brain that control hunger
and metabolism," he continues.
In fact, it is also possible to become leptin-resistant.
How this process occurs is the focus of much research, but
Rosedale suggests that leptin-resistance is similar to insulin-resistance
in that it occurs after being overexposed to high levels of
the hormone. At this point, the body no longer responds to
the hormone, much like you no longer notice a bad odor after
being exposed to it for a while, Rosedale explained.
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The mouse on the right has a mutation in the leptin
gene, which causes morbid obesity.
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Much like high blood sugar levels result in surges in insulin,
sugar metabolized in fat cells causes the fat to release surges
in leptin. Over time, leptin-resistance may develop.
Can Leptin be Used to Help Lose Weight or Prevent Diabetes?
As it stands, leptin is still a mysterious hormone that researchers
are trying to sort out. To put it simply, though, overweight
people tend to have very low levels of leptin in their systems
(they may have disruptions in leptin signaling or they may
be leptin-resistant, for instance). And, studies have found
that feeding leptin to overweight mice causes them to lose
weight. This effect was not observed in humans, however.
For now, the best way to reduce your chances of diabetes
and obesity (and other diseases like heart disease and accelerated
aging), according to Rosedale, is to avoid surges in leptin
(which can eventually make you leptin-resistant).
Eating the typical American diet, full of refined sugars
and other processed
foods, is a surefire way to cause surges in leptin. Focusing
your diet on simple, mostly unprocessed foods like vegetables
is currently the best way to reduce surges in leptin and leptin-resistance,
Rosedale says.
So for now there is no magic leptin injection or pill to
make you lose weight and prevent diabetes. The good old advice
of eating a healthy diet, though, will help to keep your leptin
levels normal, which is key to a healthy weight and life.
Recommended Reading
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the Health Risks of Processed Foods -- In Just a Few Quick,
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Your Weight is an Issue, This is (By Far) the Most Important
"Secret" You Should Know
Sources
Medical
News Today November 15, 2005
Science
Daily November 7, 2005
Cell
Metabolism March 2005; Vol 1, 169-178
What
You Don't Know About Leptin Can Make You Fat
Leptin:
A Missing Link Between Obesity and Diabetes?
Harvard
School of Public Health: Diabetes