If a food has absolutely no sugar or carb grams you can enjoy more than one serving.  Green tea is one of the few items of which you can have an unlimited amount.  

Some 0/0 items contain carbs but remain under 5 grams for one serving only.  For example, one packet of Truvia – a recommended sweetener on the Belly Fat Cure™ - contains 3 grams of carbs per serving.  Consuming 2 packets of Truvia brings your carb gram total to 6 and it now must be counted as one serving for your day.