Ok here is the thing about tea: it's being marketed with its health effects blown out of proportion.
Green tea and to a lesser extent, oolong(wulong) and black tea, can speed up your metabolism although the amount it does and the dosage are widely variable from study to study. I've read reports of 1-4% boost in BMR if you drink 60 to 80oz of tea a day. Hardly practical when you can get rid of more calories from your diet by not snacking on those potato chips each day. The effects of the caffeine it contains has negligible effects on metabolism. Tea also has antioxidants and you may be swayed to drink it as part of a long term healthy lifestyle.
Oolong tea isn't anything spectacular. Now white, green, oolong, and black tea all come from the same plant. White tea is young tea leaves that are steamed to stop oxidation, green tea is steamed to prevent oxidation, and black tea is left to oxidize (much like when a sliced apple turns brown). Oolong tea is slightly oxidized; it's the middle ground between black and green teas. Oolong tea has a more complex, less grassy flavor than green tea and is enjoyable to drink.
Tea also works on another level. It has more flavor than water and is calorie free, so you're not racking up the calories as you would with soda, milk, juice, and alcohol. Studies have found the average American easily consumes 30% of the calories they need a day from what they drink.
I buy my tea from LINK REMOVED Seven Cups Fine Chinese Tea » Seven Cups Fine Chinese Tea[/url] They are the sole importer for a few varieties and they also stock certified organic teas. Shoot them an email if you need a recommendation. Please note that the majority of growers produce a quality product but may not be certified organic because of the cost involved to get certifying body approval.
The best thing you can do for your weight and health is to stop searching for gimmick answers and eat a healthy diet and exercise.