I agree with what you said, though I've found that there are sometimes exceptions to the rule. If the narc is part of the family and you don't give them what they want and/or keep showing them up in any way, sometimes they won't just go away. Instead, they will try to learn all they can about the things that are good about you, and then spread the exact opposite in the form of blatant lies to destroy you. This has happened to me and to a good friend, different Narcs, same tactics.
That can come back to bite them though, since some people they tell the lies to will like you and not like them, and will come and tell you about it. They definitely have weaknesses, one of which is that despite their lying, they cannot read other people, or tell at all when they are being lied to, so flattery can be used to control them easily, they are so desperate for a supply of attention. They can't keep friends, and have no concept of the loyalty involved, so they will go and spread lies to your friends, who will tell you what they said or did right away.
How do you not show any emotional reaction, especially being such a feeling-dominant person? That is the question for me. Studying detachment should help, but I can't seem to master it, despite years of meditation on it. Do you have any helpful hints on how you manage to stay detached? Many things work for me in practicing when meditating, but then one of them drives me right up a wall again, and I blow a gasket. I have tried admitting I can't handle it myself and giving it all to Jesus, but it is still going on. Can you always keep your cool now?
For the carb cravings, you might try a magnesium drink like Natural Calm and use it to wash down a couple capsules of L-tryptophan. That would give you the same hormones as most carbs, though not as many as chocolate. Chocolate raises every neurohormone that feeds any type of addiction, so I hear you loud and clear on those M & Ms!