|
Green Tea and Obesity
Green tea has
become the latest weapon in the war on weight. Oprah is a recent
enthusiast, vowing that she’d trade her coffee for green tea when Dr.
Nicholas Perricone told her she could lose weight simply by making this
substitution. But does it really work?
The results of some
new studies are promising, indicating that green tea can increase the
rate of calorie burning, prevent excess weight gain and even reverse
established obesity. And although most tests have been performed on
laboratory animals, at least one with humans showed that taking in the
equivalent of 3 cups of green tea per day helped the body burn a
significant amount of additional calories.
-
Increased rate
of fat burning - A 1999 study published in the American
Journal of Clinical Nutrition looked at the effects of green tea
extract on energy "burning" in humans.1 Men who took daily
doses of a green tea extract containing EGCg plus caffeine, in an
amount equivalent to that found in about 3 cups of green tea, burned
about 80 more calories per day than those who didn’t take the extract.
(Taking the caffeine without the EGCg didn’t have the same
effect.) While burning an extra 80 calories per day may not seem like
much, over the course of a year that adds up to 29,200 calories, or a
little more than 8 pounds lost – without making any other changes!
-
Prevention of
excess weight gain - In a study involving animals, green
tea extract helped prevent obesity. Two groups of mice were placed on
a high-fat diet designed to ensure they would gain weight, with only
one group also receiving green tea extract. The mice that were given
green tea extract ended up gaining 47% less weight than those that
didn’t get the extract.2
-
Reversal of
obesity - In a 2005 study published in the Annals of
Nutrition and Metabolism, green tea extract actually helped to
reverse established obesity. Rats were deliberately overfed to
make them obese. But when the obese rats were given supplemental EGCg,
the amount of fatty tissue on their bodies decreased markedly,
reversing their obesity.3
What happens in the
body to produce such fat-fighting results? Green tea’s EGCg is believed
to rev up the fat-burning effects of brown fat,4 a special
kind of body fat that burns calories at a very high rate. In animal
studies, green tea has been found to help send glucose to muscle tissue
where the glucose is more likely to be burned, rather than to fat
tissue, where it’s more likely to be stored.5 And in
test-tube studies, green tea extract inhibited the action of
fat-digesting enzymes,6 meaning the fat from foods may be
less likely to be broken down and absorbed in the digestive tract.
More research is
needed before we can say that green tea definitely helps you lose
weight, but it certainly looks like a good bet!
For a
simplified look at the studies on
green
tea's anti-obesity effects, click here.
Footnotes:
1)
Dulloo AG, Duret C, Rohrer D, et al. Efficacy of a green tea extract
rich in catechin polyphenols and caffeine in increasing 24-h energy
expenditure and fat oxidation in humans. Am J Clin Nutr
1999;70(6):1040-50.
2)
Shimotoyodome A, Haramizu S, Inaba M, et al. Exercise and green tea
extract stimulate fat oxidation and prevent obesity in mice. Med Sci
Sports Exerc 2005;37(11):1884-92.
3)
Wolfram S, Raederstorff D, Wang Y, et al. TEAVIGO (epigallocatechin
gallate) supplementation prevents obesity in rodents by reducing adipose
tissue mass. Ann Nutr Metab 2005;49(1):54-63. Epub 2005 Feb 25.
4)
Choo JJ. Green tea reduces body fat accretion caused by high-fat diet in
rats through beta-adrenoceptor activation of thermogenesis in brown
adipose tissue. J Nutr Biochem 2003;14(11):671-76.
5)
Murase T, Harmizu S, Shimotoyodome A, et al. Green tea extract improves
running endurance in mice by stimulating lipid utilization during
exercise. Am J Physiol Regul Integr Comp Physiol
2006;290(6):R1550-56.
6)
Juhel C, Armand M, Pafumi Y et al. Green tea extract (AR25) inhibits
lipolysis of triglycerides in gastric and duodenal medium in vitro. J
Nutr Biochem 2000;11(1):45-51.
|
Nadine Taylor, M.S., R.D. presents
GreenTeaLibrary.com,
the most comprehensive collection of scientific information
describing the health benefits of green tea.
|
|
