Catechins the antioxidants found in high amounts in green tea have been shown to be helpful in promoting weight loss, specifically belly fat. Decaf green tea is OK if caffeine is a problem. However, some decaffeination processes can lower the antioxidant content so add an extra cup or two per day.
In a study at the USDA Human Nutrition Research Center on Aging at Tufts University, people who drank 3 cups of green tea a day lost twice as much weight as those not drinking tea. The tea-drinking group also lost significantly more belly fat than non-tea drinkers.