What? Did I stutter?

I've read that when a woman tells her man that he's doing something that makes her unhappy and suggests a way to alleviate the issues he believes that she is being helpful, but the man does not see it this way at all. In the man's mind she is nagging. Subsequently he tunes her out, regardless of how astute her observation may be. In Chuck Snyder's books Incompatibility: Still Grounds For A Great Marriage and Men: Some Assembly Required, he says that our only hope is to cross our fingers and pray that some other man will come along and give our man the same advice that we did. Because when this happens our man will be struck by the other man's genius (originally the woman's genius mind you) and possibly even motivated to change.

Personal Example:

My fiance has a fast metabolism. He comes from a long line of tall slender men. He is built exactly like his father who is built exactly like his father. No matter what my fiance eats he remains approximately the same size (except in the summer he looses 10 pounds from the heat). I am very jealous of this trait of his, but that is beside the point.

This seemingly physical perfection does not come without it's price. If he's not careful his blood sugar will drop drastically and, as one friend who has a similar situation stated, he will be "possessed by the demon." He becomes irritable and introverted and often refuses to eat at this point. Argh!

So here's the interesting part. I've been telling him for the three years that we've been dating that this is an issue. Furthermore he knows it's an issue himself. Often times when he is cranky and irritable (which I take personally and feel hurt) he cites hunger as a reason. So he's not oblivious of this correlation, but that doesn't mean he's changed his approach or attitude in anyway.

And then he's tells his dad a story in which "hunger made him act like a jerk" and his dad says, "I knew this guy who was hypoglycemic. Maybe you are too." Now he gets it. Now he thinks, "Maybe I should go to the doctor and get tested. Maybe I should think about changing the way I eat." Grrr! I know I should be happy because he might actually do something about this behavior now, but seriously, I spent three frustrated years trying to beat this logic into his brain.

Sidenote:

I'm not entirely convinced that he will do much of anything though. He seems to like to be able to blame his negative traits on "his disorder." First I tell him that he has to get diagnosed by a doctor to have a disorder and second he's gonna have to change his diet. I think he tuned me out already. Maybe his dad will tell him. I can only hope.