Consumption of green tea at a dose of 4-6 cups daily for 6 months (480-960 mg of green tea catechins) has resulted in occasional episodes of toxic hepatitis, and the risk appeared to increase with chronic use (120). Caution use of green tea in patients with other forms of hepatitis, liver dysfunction, use of other medications cleared by the liver such as acetaminophen.
No adverse effect of green tea was found in a 12 week RCT but the study was fairly short term and both the study group and the control group had a low incidence of elevated liver function tests (115).
Summary: Green Tea
An average overweight person can expect to lose about 2-4 pounds of weight in 12 weeks with consisted intake of about 4 cups of green tea daily.