The University of Maryland Medical Center reports that green tea contains antioxidants, which protect cells, tissue and organs from damage caused by free radicals. Furthermore, several clinical studies have concluded that green tea may promote weight loss; however, results are not guaranteed and differ by individual. Consult with your medical adviser before starting a weight-loss program.
Fat Burning Properties
Green tea contains both caffeine and antioxidants, known as catechins and polyphenols. Katherine Zeratsky, R.D., L.D., of Mayo Clinic, reports that caffeine may slightly boost weight loss; however, further scientific evidence is needed to validate this claim. It is theorized that caffeine serves as an appetite suppressant, contains thermogenic properties and has a diuretic effect on the body, all of which can aid in weight loss. University of Maryland Medical Center notes, however, that while caffeine may offer mild metabolic improvements, the main sources of green tea's weight-loss effect lie in the antioxidants; additional research is necessary to confirm this claim. Green tea may also regulate blood-glucose and insulin levels. If insulin levels are unbalanced, the body may resort to storing fat rather than burning it for energy.
Expert Insight
Several studies support green tea as a weight-loss agent. A 2008 study published in "Physiology & Behavior" reports that obese participants who consumed green tea over a 12-week period experienced quicker weight loss than those in the control group. Another study published in the February 2009 edition of "The Journal of Nutrition" found that men who ingested 600 mg of green tea catechins lost an average of 5.4 lbs. over a 12-week period. The U.S. Department of Agriculture published a study in which individuals who substituted tea for water increased fat oxidation levels by 12 percent, which led the body to burn an additional 67 calories over the course of the day.
Preparation
MedlinePlus recommends steeping 1 tsp. of dried green tea leaves per 8 oz. of boiling water for several minutes before straining. Consuming three cups of green tea per day provides 240 to 320 mg of polyphenols and 124 to 208 mg of caffeine.
Considerations
Although several studies demonstrate green tea's weight-loss effect, many of those studies also mention that the participants were placed on a restricted diet. While green tea's thermogenic properties may induce weight loss, experts agree that green tea in conjunction with a healthy diet will enhance weight loss efforts and that green tea alone is not enough to promote effective weight loss. A pound of body fat equates to 3,500 calories, so in order to lose a pound a week, you need to have a daily deficit of 500 calories. The calorie deficit may be in the form of a restricted diet plan or increased physical activity.
References
- MedlinePlus: Green Tea
- USDA: Brewing up the Latest Tea Research
- "The Journal of Nutrition"; Green Tea Catechin Consumption Enhances Exercise-Induced Abdominal Fat Loss in Overweight and Obese Adults; Kevin C. Maki, et al.; February 2009
- "Physiology & Behavior"; Effectiveness of Green Tea on Weight Reduction in Obese Thais; Auvichayapat P, et al.; February 2008
- Mayo Clinic; Does Caffeine Help With Weight Loss?; Katherine Zeratsky, R.D., L.D.
- University of Maryland Medical Center: Green Tea
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