I imagined the whole food stealing thing to be really bad but it's not at all, I'm so glad I put off buying a mini-fridge till I got here cause I realised I don't need one.
None of my flatmates really talk or interact with each other (if we are cooking in the kitchen at the same time we will chit chat but that is it) so our kitchen is literally just a place 5 strangers happen to use.
We all have separate shelves in the fridge and freezer and keep all our own pans/crockery etc in our own cupboards so it is easy to know who's is who's and no one uses each others stuff unless we ask beforehand and wash it up as soon as we finish. We have a shared cupboard and a shared shelf in the fridge for overflows but even then no one takes other peoples food. We pretty much practice 'if you didn't buy it, don't use it.' But we never discussed this before hand.
Once someone took all my diet cokes out of the fridge (I always have 4 in the fridge at any one time). So I got in from work at 4:00am headed to the fridge for a refreshing can o' coke and they were gone. I was mega pissed so left a post it note in the fridge saying 'To whoever decided to drink ALL my diet cokes, DO NOT take my things without asking!!!' After that it never happened again.