As a binger, i know that its hard to change your mind unless you decide to resist it.
People say that you can talk yourself out of a craving for food. I don't know. I can do it with cigarettes (as per when i first quit) but the times i tried to resist a craving, well i did it but underlying feeling tended to stay. Although i remember it did come can go but i binged on less fattening things. Although also i wasn't so near a shop that i could go and do the worst damage. But did my best to binge on the sweetest baddest thing i could put together.
So from my experience, i am not sure she can skip it. Sometimes a craving feels so much deeper than just a thought. So just hugs and go back and talk to the doctor about whether this is the right med for you.
I am not sure its the prozac but it could be contributing. Did you never need to binge before?