ok, i've read all your entries. If you stop buying the junk food, you can't eat it, right? Your kids won't starve if you don't have cheddars etc. So remove the temptation!
You can do this -think of it as a total break from food. I put my shakes etc in their own cupboard so i don't see any other food when it's my mealtime. I make sure i eat my shake/soup/bar at least 20 mins before i prepare my husband and son's meals, and i have a half pint mug of water beside me to sip so i feel 'full' whilst i'm handling food. Maybe that will help?