The health claims regarding green tea imply that this beverage has extraordinary qualities. As an antioxidant, it may provide some protection against cellular damage caused by free radicals, by-products of normal metabolism and exposure to toxins. One of the claims about green tea that has gained a great deal of attention is its relationship to weight loss. With over two-thirds of Americans overweight, the promise of a weight loss aid is a powerful allure. However, the U.S. Food and Drug Administration has not evaluated these statements for their validity. If in doubt, consult your doctor before including green tea in your weight loss regimen.
How Green Tea Works
The health benefits of green tea surround ingredients called catechins. Chemicals found in catechins inhibit some enzyme activity that may explain its ability to increase endurance. A 2005 study by Kao Corporation in Japan found that the endurance level of mice fed green tea extract increased 8 to 24 percent after 10 weeks. Researchers concluded that the presence of catechins and caffeine were responsible for these effects.
Types
While there are several green tea varieties, they are all derived from a plant called Camellia sinensis as are white, oolong and black teas. The difference between the types lies in the processing. Differences between the types of tea may lie in regional variations due to soil, climate and other environmental factors. Teas will also vary in grade used in production. The minimal oxidation or fermentation of the leaves gives green tea its color.
Caffeine Factor
When determining if all green teas act similarly on weight loss, the question of caffeine content has to be considered. Both caffeine alone and green tea may stimulate calorie and fat burn. A 2010 study by Maastricht University in the Netherlands concluded that both of these products could be effective additions to a weight loss plan. However, a 2009 study by Waikato Institute of Technology in New Zealand came to a different conclusion when considering green tea and endurance training. Researchers found that caffeine alone improved endurance and fat burn during exercise, suggesting that the caffeine in green tea offers the primary benefits.
Guidelines for Use
The question of using green tea for weight loss rests on your sensitivity to caffeine. Some individuals may experience headaches, nervousness or other symptoms from caffeine consumption. A 2005 study by Maastricht University in the Netherlands found that a green tea mixture that included 150 mg of caffeine improved weight maintenance in women who habitually drank low amounts of caffeine. This amount is equivalent to the amount of caffeine in one cup of coffee. Herein lies the difference between the different green teas. While other health benefits may exist with decaffeinated green teas, weight loss occurred with green teas containing caffeine. (Res. #1)
References
- Centers for Disease Control and Prevention: Obesity and Overweight
- U.S. Food and Drug Administration; Dietary Supplements; December 16, 2010
- "American Journal of Physiology, Regulatory, Integrative and Comparative Physiology"; Green Tea Extract Improves Endurance Capacity and Increases Muscle Lipid Oxidation in Mice; T. Murase, et al.; March 2005
- Tea Guardian: Categorization of Teas
- "International Journal of Obesity"; Thermogenic Ingredients and Body Weight Regulation; R. Hursel and M. Westerterp-Plantenga; April 2010
- "International Journal of Sports Nutrition and Exercise Metabolism"; S. Dean, et al.; December 2009
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