I don't mind at all.
First let me address the 80% mental by saying that it might even be more like 90% mental. In my experience most people have a mental switch that has to be flipped before they get really serious about their goals. A lot of people make goals and attempt to work towards them, but in many cases it takes more than that, especially if those goals are more difficult. Therefore I consider reaching fitness goals to be 80 or 90% mental because if your head isn't truly in it then it dosen't matter what your nutrition or exercise program is.
For me personally, the further I've come towards my goals the more mental it has become. Yea, the nutrition and the workouts have gotten more complicated and difficult, but it's the mental battles that are harder. Keeping that drive has been difficult especially since I'm not really doing a show, this is just for myself to see how far I can take it. I want to reach that 6% but it's tough when I'm already getting this positive feedback from people that says, "You look great" but then is followed by "so why can't you have a beer" or "a cookie" or whatever they happen to be eating or drinking in front of me. So a part of you says "Yea I've already come this far, what's a little cookie going to do." Now it's all a mental battle to keep that resolve.
As far as your second question, I honestly have not read all of those different types of nutritional plans. So I can't tell you that one is better than another. With client's I work with I try to asses what there level of commitment is and then try to fit the nutrition to that. Again it comes back to the mental aspect. Even if TNT, or Adam's diet, or any other diet is the greatest plan in the world a person who is mentally unable to follow it will not get the results and will ultimatly become discoraged with their failure. By the same respects each of these plans has great success stories, so they have obviously worked for some people.
So to sum up what I mean by "the right nutrition", you have to choose a nutrition program that matches your level of commitment. From there it's a matter of compliance, and that's all mental. My most recent nutrition plan is pretty monotonous and I would have failed at it if I wasn't in the right mindset.
A perfect example of this is I've been working with one of my cleint's who has been following pretty much right along with me through this program, and when we got to this last phase he wasn't able to keep up with it. His work has been crazy and he just didn't have the emotional energy left to maintain the necessary focus. He's made great progress and is not overly discouraged so we set up a maintence program to keep him where he is and he said when things calm down at work he wants to give it another go.
I hope I've answered your questions and not just rambled.
