How many cups of green tea should i have in a day for it's all benefits like healthy skin, weight loss etc ?

At least 5 but...: This is a case where, to a certain degree, more is better, except you want to not overdo caffeine. Research has shown that adults in Japan who had 5 or more cups a day had the most benefits, but I would not do more than 6 cups unless some of it is decaf, in which case you can drink as much as you can! One can also take capsule or tinctures that contain concentrates. See http://tinyurl.com/oy6e59p