Caffeine
People consume everyday products, such as coffee, tea,
and
sodas that contain caffeine. It can
also be
found in plant products such as guarana
and yerba maté. Guarana contains levels that are twice as potent as coffee. Several
over the counter pills like No Doz®, Enerjets®, and Vivarin® have it in them.
How
It Works in Weight Loss
It
is not exactly certain how caffeine may work in helping people lose
weight, and some studies show that it has no real effect. Most studies
were done with rats in the lab, and there are not as many studies on
actual people. There are, however, several theories as to how it might
work.
Drinking
about 6 cups of coffee causes you to burn an extra 100 calories per day. In
long term use, caffeine reduces the number of fat cells and size of fat
pads. The break down of fat increases after the ingestion of coffee.
It
can get into the brain where it can stimulate the sympathetic nervous system
and increase the amount of adrenaline circulating in the body. It can
also increase chemical cellular signals that tell cells to break down
more fat.
Physical activity may also be increased. It improves exercise performance as well. The International
Olympic Committee has even placed an upper limit on blood levels for legal
athletic competition. More physical activity equals more calories
burned every day.
Although
it does not seem fair, studies have shown that these weight
loss effects are greater in people who are not obese compared
to
those who are.
Some studies with coffee suggest that
other
chemicals in the coffee are what actually cause weight loss. Several
others do point to caffeine as being the key player. There are no
studies on guarana by itself for weight loss.
Much
more
research needs to be done on the real benefits and risks before
it can be recommended as a weight loss supplement.
Side Effects
As
with any other drug, there are side effects. It can raise blood
pressure. This can be very serious in people who have heart and blood
vessel disease or who already have high blood pressure. It may also
decrease the body's sensitivity to insulin and worsen diabetes.
Because so many people, at least in the United States, have these
diseases, it limits the usefulness of caffeine as a weight loss aid.
Some other side effects are: chest pain, fast heart beat,
delirium, dizziness, irritability, insomnia, restlessness, and others.
Withdraw
symptoms include: headache, irritability, anxiety, depression,
drowsiness, and fatigue.
However, it is generally
considered to be safe when consumed in
moderation, which is about three 8 oz cups of coffee or less. Pregnant
women
should take in less than that and talk with their doctors.
Caffeine
was often combined with ephedra,
before its ban,
in weight loss pills.
It is important you
discuss any weight loss or exercise plan with your doctor. Only you and
your physician can decide what is best for you. Some people have
certain conditions that prevent them from doing all exercises, and goal
body weights may be different for different people. You need to discuss
all these things with your physician before starting any weight loss or
exercise program.
This
article was written by
John
Vickery, MD.
References Am J
Clin Nutr. 2006 Oct;84(4):682-93. Am
Fam Physician. 2004 Nov 1;70(9):1731-8. Lore of Running 4th edition,
Noakes, chapter 13 Lexi-Comp database accessed on
4/9/08. Prim Care Clin Office Pract.
2002 Jun;29(2)279-95.

Last updated 7/19/09
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