GREEN TEA!!!

How many ounces(cups), of Green tea is recommend to drink a day.. I been drinking 24ounces a day of green tea on ice, but a coworker the other day toll me that what I was doing in a way isn't good because in the long way it helping to burst my metabolism and lose weight but at the same time I am messing up my kidneys with all the green tea that I am drink... But I also have water not only green tea.. I realize that when I have my green tea early in the morning I got a lot of energy... And i need it because of my job y pass 8 hrs on my feets daily.... So any one could tell me if I am doing good or better to reduce the amount of green tea for only 8 ounces?????