Originally Posted by Midnightdraven
No. You can log into FB app. You can remain logged in and close it.
It does nothing until you open it.
By being logged in, EMAILS for facebook, get intercepted by the app, and you get the notification. The app doesnt need to be running in the background to do this.
FB app will only load the notification, once you click on, at which point it starts retriveing and refreshing feeds, messages, friends list etc.
If you've closed it, but still logged in, it does NOT use data.
Oh I guess it just seemed like an obnoxious stream of updates and messages. (All of extreme importance).
But yeah, I re-installed, and seems to be zero data flow even if the app shows in the background. Although I unchecked those 3 options on connecting Calendar, Message, and Contacts with Facebook.
So back to the OP, try to wipe the OS and reinstall then. If you insist it's not the apps, then get down to no additional apps and find out. For all we know, maybe your neighbor is tethering to your phone at night over bluetooth and browsing the web.