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.