We had a communal fridge in halls . We had 2 fridges between 12 of us on our floor. There is a certain acceptance that things like milk , sugar , choccy etc will be consumed at times of need. Generally rolling in the early hours and having the munchies !!!
Lets be honest we still have the "who has used my milk" discussions at work even though the bottles are all initialed
At uni we had a 'communal' biscuit tin where we took in turns to buy. This prevented some midnight feast raids .
Generally you will not be able to bulk buy food as there simply will not be enough storage space . Main meals won't be touched , so it's just about reducing the risk really. Lets face it - anyone who buys chocolate and intends not to eat it for days is seriously asking for trouble