If weight loss is one of your top health goals, green tea may help. Some studies show that substances in green tea may offer several weight-loss-promoting effects, such as speeding up your metabolism and suppressing your appetite. Although the antioxidant-rich brew won't help you shed pounds on its own, there's some evidence that drinking green tea may support your weight loss efforts.
How Might Green Tea Promote Weight Loss?
Green tea contains caffeine, which is known to increase thermogenesis (a biological process involved in burning calories). In a 2007 report from the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, scientists state that green tea may fight the decrease in metabolism that typically accompanies weight loss. According to the report's authors, green tea may also inhibit the effects of catechol-O-methyltransferase (an enzyme known to trigger the breakdown of brain chemicals involved in regulating appetite).
Is Green Tea Effective?
Certain antioxidants found in green tea seem to have a "small positive effect" on weight loss and weight maintenance, according to a report published in the International Journal of Obesity in 2009. In their analysis of 11 studies on green tea and weight loss or weight maintenance, researchers found that green tea antioxidants known as catechins may help increase metabolism.
Still, the National Institutes of Health (NIH) caution that there isn't enough scientific evidence to determine whether green tea is effective for weight loss. However, epigallocatechin gallate (a catechin found in green tea) may help moderately overweight people lose weight, according to the NIH.
Is It Safe?
While green tea is likely safe for most adults, drinking more than five cups a day may lead to caffeine-related side effects (such as headache, nervousness, sleep problems, and irregular heartbeat). The caffeine in green tea may also aggravate some health conditions, including anxiety, high blood pressure, and diabetes.
When Should You Use It?
For most adults, moderately increasing green tea intake may yield some weight loss benefits without causing negative health effects. But in order to experience significant weight loss, it's important to combine a healthy diet with regular exercise (including at least two and a half hours of moderate-intensity aerobic activity and two strength-training sessions per week). If you're considering the use of green tea supplements (or any other natural weight loss aid), make sure to consult your physician before beginning treatment.
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Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J. "Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity." Int J Obes Relat Metab Disord. 2000 Feb;24(2):252-8.
Hursel R, Viechtbauer W, Westerterp-Plantenga MS. "The effects of green tea on weight loss and weight maintenance: a meta-analysis." Int J Obes (Lond). 2009 Sep;33(9):956-61.
National Institutes of Health. "Green tea: MedlinePlus Supplements". January 2011.
Shixian Q, VanCrey B, Shi J, Kakuda Y, Jiang Y. "Green tea extract thermogenesis-induced weight loss by epigallocatechin gallate inhibition of catechol-O-methyltransferase." J Med Food. 2006 Winter;9(4):451-8.
Westerterp-Plantenga MS. Green tea catechins, caffeine and body-weight regulation." Physiol Behav. 2010 Apr 26;100(1):42-6.