Insane Data usage by android OS

From the time I switched to 3g data plan, my data usage had gone high for reason. Even while I was not using my phone, Data was being used up continuously. Now this time, my 1gb data was used up in like 10 days and I was very surprised by this.

So I check my data usage, app by app and saw that android os was using a major chunk of the data. I did some research and found out that this was a very common problem and solution which was generally suggested was to opt out Google data sync which can be found in the settings. I have done that and in merely one day, I see that my data usage has significantly gone down.