You must have a rogue app, because this should not be happening.
Go into Settings > Manage apps, ensure you are in the 'All' tab, and then press the Menu soft-key (left of Home button). There will be an option to sort by size. Select it, and the highest usage apps will appear at the top in descending order. One (or more) of the top 5 is the culprit. You can try going into Settings > Connections > Data usage, and see if you can restrict the app from using background data. If not, then your only options are to clear cache on the app(s) in question (only a temporary solution), or uninstall and find a replacement app that is more resource friendly. GL!
