Tested on iphone 5s, Must be the same for ANDROID users as well.
No settings can take away the fact the APP is just a website sitting on your phone and always refreshes and syncs and downloads DATA in background. Even if background operations are off, they will do it when you open the App and you will have to WAIT till your FB profile data is sync'd with the APP on your phone. Push notifications + background operations are Battery & Data eaters. Data Plan = Money in the world of Smartphone.
If i may Ask, Can you think of using FB on the Mobile Browser instead if you were to login only once into FB and 1 TAP takes you straight to LOGGED-IN FB Mobile Website for a Battery Friendly and Data Friendly approach to FB?
I ran a test on my iPhone 5s Today (27th october 2014)
FB app store data size - 70.5 MB ( this is what is written on the app store)
After Install app size - 104 MB (probably downloaded updates)
First time App opening size in settings - 114 MB ( not sure why it took 10MB just to open the FB app)
After login to FB, app size became - 131MB ( 17MB just to login to FB on the native APP)
So FB instaly became 131MB on my phone without even browsing it for ONCE.
After browsing my own profile + 50 photos. and 1 video link, FB App size - 197 MB
I tried a new app called "whats local today", it provides a mobile website to access fb,twitter,linked in,google+,tumblr on 1 screen.
SEE for yourself what were the results of the same test on my iPhone 5s.
Whats local today App store size - 56.6 MB (this is what is written on the app store)
After install app size- 64 MB
First time app opening size - 98.4 MB ( downloaded updates after opening the app for the first time)
After login and browsing on fb - 102 MB.
It presented a mobile website of FB where i only need to login once and it opens fb for me the next time i open this app.
After browsing my own profile + 50 Photos + 1 video link of FB through this app, App size - 119MB
Its a new style mobile browser. login once only. then fb mobile website available at a single tap.
uses 35-40 % less data than fb native app.
Please test it for your self. i tested it on iphone 5s by instantly switching in between Storage SETTINGS PAGE and the Steps i mentioned Above from App store to APP Install without even browsing once)
"whats local today" Doesn't run in background at all because its a browser loading a simple page.
Messaging is available but no push notifications because of the mobile website version of fb.
"whats local today" is a cool, battery & data efficient way of using fb and other social media. Only need to login once and browser automatically opens it next time for you so it works just like an APP ICON.
I have deleted the FB + other native apps from my phone and the battery has improved significantly.
whats local today works well for me as FB is still just a TAP away & provides Messaging as well.
please try it for yourself and you shall SAVE YOUR MONEY by using lesser Mobile DATA.