Google Play Services High Internet Consumption

TL;DR:

1. Install Autorun Manager (you must have root access)


2. Go into the settings and enable "Show System Entries" and "Enable system app disable"


3. Disable permissions for "com.android.gsf.update.SystemUpdateService$Receive" and "com.android.gms.update.SystemUpdateServiceReceiver"


4. Sigh in relief as your mobile plan is freed from Google Play's insatiable hunger for data.

After a long afternoon of googling, I ended up finding some old but interesting thread on reddit from 2013 that detailed a problem very similar to mine. Although they talk about the Nexus 4, what they discussed seemed to apply for my Nexus 5.

Caseyls, the original poster, seemed to have concluded that the problem is that Google Play services is constantly downloading an update:

[...] Your phone is trying to update to [a newer version of Android]. It downloads the update files, but then when it goes to try to tell you to update, [some] of the files are [missing]. [... Then] your phone deletes the update files, and tries [to download them] again. And again. And again.

The poster suggested solutions were pretty much the same ones I found all over the internet, but an user named Dourel suggested something useful they found on XDA:

Install Autorun Manager from the Play store. Then enter its recommended advanced mode. Go into the settings and enable the following : system entries and system app disable. Disable com.android.gsf.update.SystemUpdateService$Reciever under Google Service Framework

So as it was suggested, I installed the app and enabled the options "Show System Entries" and "Enable system app disable" in the settings, like in the picture below:

Then looked for Google Play Services in the list of apps, expanded its contents, and looked for "com.android.gsf.update.SystemUpdateService$Receive". Sadly, as the first picture below shows, that permission had already been disabled in my case (don't know how that happened though). So I thought I was back at square one.

But I wasn't going to give up just yet. Searching more thoroughly I found out there was another service called "com.android.gms.update.SystemUpdateServiceReceiver" that was checked on. So naturally I checked it off. To test it whether it worked or no, I left the Wi-Fi on all night and crossed my fingers for it to work.

The next morning, Onavo Count (the app I mention in the question) reported that no substantial amount of Wi-Fi data had been consumed, so I proceeded to test leaving the phone's 3G data plan for the rest of the day (Wi-Fi off of course). To my rejoice, as of tonight (12 hours later), my data plan has barely even been used. Less than 1MB was consumed all day! Yay =)

So that's it! The most effective solution I could find to stop this madness. I hope it works for anybody else.