Having my own stuff really does help, but in addition I simply stopped buying junk, or the things necessary to make junk.

I buy my dh the kinds of chips and snacks that I don't like, but he does, and he gets his junk at work from the vending machine and never brings it anywhere near me. I'd fail if he did, and he knows it. He's great that way.
My son has lost weight with me being on this woe even though he's not on a diet because the junk just isn't there for him.
I know for some it doesn't do any good to talk, but make it an effort for them to try to sabotage you and just simply only buy things that are legal for you, and maybe some things like bread and rice for the people who feel they need it. It won't hurt them.