Well, not trying to be argumentative here, honestly. It's just that I happen to be in the biotech industry, and I interpret clinical data every day (for over 20 years). I do agree that there is a trend toward an effect on weight loss (separating out other beneficial effects here), but there have been no well controlled trials of a sufficient size to call the effect proven. The trials cited are anywhere from 10 to 50 or 60 patients, and on average show a difference of 4% for the ones that worked (meta analysis did not include ones that didn't work, which is not valid), and that's just no where near enough to be be proof. You need several hundred, or even thousands of patients for definitive proof. You can check out the clinical trials for several obesity products that some biotechs are trying to develop (Qnexa, Contrave, Lorcaserin). These companies have done extremely well monitored trials in thousands of patients to try to prove an effect, and that's what needs to be done.
I've reviewed all the studies you cited as well as many others, and the effect is marginal at best, and within error bars, or negative. Below is the best controlled study I've found, and contrary to the author's conclusion, a P value greater than 0.05 is not significant (the study P value is 0.079), so I don't know why he says it is, that's just not scientifically valid. The author even says at the end that further study is warranted (and needed, and I agree).
Green tea catechins linked to weight loss: Study
With all that said, again, I don't want to rain on a parade, and many of the other positive effects of green tea, such as anti-oxidant effects, have been proven to reduce inflammation and other benefits, so I drink the stuff for sure and believe in it's value strongly.
Just keeping an eye toward accuracy in science here, particularly given the amount of anti-obesity information we are barraged with on a consistent basis.