Researchers say the results indicate that substances found in green tea
known as catechins may trigger weight loss by stimulating the body to
burn calories and decreasing body fat.
The findings appear in the January issue of the American Journal of Clinical
Nutrition.
Green Tea: Fat Fighter?
Black tea, oolong tea, and green tea come from the same Camellia sinensis
plant. But unlike the other two varieties, green tea leaves are not fermented
before steaming and drying.
Most teas contain large amounts of polyphenols, which are plant-based
substances that have been shown to have antioxidant, anticancer, and antiviral
properties.
However, green tea is particularly rich in a type of polyphenols called
catechins. These substances have also been shown to have anti-inflammatory
and anticancer properties, but recent research in animals show that catechins
may also affect body fat accumulation and cholesterol levels.
In this study, researchers looked at the effects of catechins
on body fat reduction and weight loss in a group of 35 Japanese men. The
men had similar weights based on their BMI (body mass index, an indicator
of body fat) and waist sizes.
The men were divided into two groups. For three months,
the first group drank a bottle of oolong tea fortified with green tea
extract containing 690 milligrams of catechins, and the other group drank
a bottle of oolong tea with 22 milligrams of catechins.
During this time, the men ate identical breakfasts and dinners
and were instructed to control their calorie and fat intake at all times
so that overall total diets were similar.
After three months, the study showed that the men who drank
the green tea extract lost more weight (5.3 pounds vs. 2.9 pounds) and
experienced a significantly greater decrease in BMI, waist size, and total
body fat.
In addition, LDL "bad" cholesterol went down in
the men who drank the green tea extract.
The catechin content varies by amount of green tea used
and steeping time. But general recommendations, based on previous studies
on the benefits of green tea, are at least 4 cups a day. Green tea extract
supplements are also available.
Researchers say the results indicate that catechins in green
tea not only help burn calories and lower LDL cholesterol but may also
be able to mildly reduce body fat.
"These results suggest that catechins contribute to
the prevention of and improvement in various lifestyle-related diseases,
particularly obesity," write researcher Tomonori Nagao of Health
Care Products Research Laboratories in Tokyo, and colleagues.
SOURCE: Nagao, T. American Journal of Clinical Nutrition,
January 2005; vol 81: 122-129.
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