what the nutritionists at Sparkpeople have said... somedays I really do preach the gospel according to spark...is that for green tea to have any real effecton metabolism you need to have a minimum of 4 -5 cups a day. but that's also adding in a bunch of caffeine..
Gree tea is good because of the anti oxidants and other stuff in it- i'd say drink it because you like it... and if there's a bonus.. well great.. but don't expect it to be a magic bullet