Below is information from Dave Werner of CrossFit Seattle about nutrition and Paleo and Zone eating.
It is possible to change your body composition and your health. Results are highly dependent on food. Exercise helps, but by itself exercise will not give you the results you expect. Our recommendations are driven by results. We have seen many different approaches tried by many different people. When one of our friends and athletes gets his/her eating right it is impossible to miss. They thrive. Their athletic performance leaps, they look great, they bounce. Seriously - bounce. People feel so good when eating right that the simple act of walking has an energy that is hard to miss.
We recommend the Paleo and Zone approaches to eating. Why? Because they work. In our years of training people we have seen uniformly excellent results in people who stick to these approaches. What results? Decreased body fat, increased lean muscle mass, increased energy levels, improved sleep and recovery, increased athletic performance.
We are not trying to sell you anything. You can't buy anything from us. We aren't going to carry any nutrition "products" ever. This is about eating real food that you get from (ideally) farms and markets, with grocery stores being the second choice. A great book about discerning "Food" from edible "products" is "In Defense of Food" by Michael Pollan. This is a short and readable discussion about making good food choices. For a much more thorough analyses of the current state of nutritional science please read "Good Calories, Bad Calories" by Gary Taubes. I believe Taubes book to be the most important work on nutrition I've ever seen. For a deep understanding of how the current nutritional recommendations came to be, this work is indispensable.
What are the Zone and Paleo diets? Not 'diets' at all really. Rather, they describe two different aspects of rethinking how you eat. We are talking about permanent changes to the decisions you make about how and what to eat.
The Zone approach concerns itself mostly with the quantity of food eaten, both total size of meals and the relative amount of protein, carbohydrates and fat eaten at each meal.
The Paleo camp is less concerned about quantity, focusing instead on quality. What you eat matters, and if making good food choices, it is hard to over eat.
For daily application here are some resources.
Our friend, Robb Wolf, has been giving great nutrition guidance for a long time. His website is a gold mine. To get you started he has written a shopping guide and several sample menus available here. He has answered many questions and compiled lots of great resources in his FAQ.