DD is 11!! Who is the boss here?Have you ruled out that there is nothing worrying her? Could there be any underlying undiagnosed behaviours that could account for this ? Is she reacting to something? Has her behaviour suddenly changed? Is there a reason?
If not, and you are absolutely sure none of the above apply, you need to get a handle on this. Remove all privileges, including going out, yes it will cause you a headache but that is parenting. Be consistent with your message and reinforce the message over and over again. You will have to go through tantrums and dramas but they will eventually subside over time when the penny drops with your DD , but, it could take months.
For want of a better word "hide" any food stuffs you can that you do not want eating all at once. Long life cupboard type stuff bag up ( to protect) and put in garage/shed, boot of car etc. Bring in as needed. Or , physically lock the kitchen to "close" it each night at bedtime. I know it sounds extreme but i had to do this for a small period when my eldest was a mid teenager and eating at all hours. I could not replenish quickly enough and it cost a fortune. I was making 3 good meals a day, plus treats and home baking. My DC was not starving by any means. Just picking and choosing what he wanted and when and i was not prepared to have my rules flouted and my finances pressured with constant shopping.
My youngest at home with me now is 14 and they would never walk out the door without my permission and /or knowledge of where they were going and with whom. It is about respect and discipline ultimately.
Op, in the nicest way are you allowing your daughter this culture of entitlement? Have you been overly relaxed over the yrs due to divorce or illness or other reasons? I admit i did spoil my children when they were very very young as I worked full time and felt guilty, took me a while and some parenting classes to see i was wrong.
That said my Dc's were not like this at that age but that could have been because i put discipline in place in the earlier years. Could you have indulged DD over the years thinking it was the best for her? I am not judging, none of us are perfect. But, you do need to get a handle on this now , she will rebel under your new regime so you need to be prepared for that and to be in for the long haul.
It appears from your post that your DD dictates everything and you need to reverse that totally. Your authority should be ever present and felt even when you are the shower. You need to regain authority OP and this is going to be hard now but you have to do it.