CCmakes3, it just so happens I was just reading an article written by an Md who is author to several womens' health books. I pulled out this exerpt for you and shortened it a little. Hope it helps.
*Along with its antioxidant and cancer-prevention properties, green tea can help you burn calories. It contains special chemicals called catechins which appear to protect a brain chemical related to metabolism. The higher your levels of this brain chemical, the greater your metabolism is and the faster you burn calories.
One cup of brewed green tea contains about 100 mg of catechins. To reap the full benefit of green tea, consume at least three 8oz cups daily (to provide roughly 240-320 mg of catechins). If you perfer not to drink the tea, either of these options provides the same level of protection: 1) 300-400 mg daily of green tea extract, standardized to 80% catechins and at least 50% epigallocatechin (EGCG). This extract is not always caffeine-free; check the label. 2) 100 mg of green tea catechins, taken three times daily. This product is caffeine-free.