In an analysis of randomized controlled trials, individuals who consumed green tea experienced a significant decline in body weight and body mass index. On the other hand, the analysis did not show any significant change in terms of waist circumference (a measure of abdominal fat) with green tea supplementation. The findings are published in Phytotherapy Research. The analysis of 26 randomized controlled trials including 1,344 participants found that body weight and body mass index significantly changed after green tea was consumed for periods longer than 12 weeks and at a dosage of less than 800 mg/day. Source
