CFP Nutrition
Part I:
First off this is only my opinion. I am always learning!  I have not only observed the diets of others over the years, but have pulled most of what I believe from my own trial and error.  I have learned a lot over the last year from my own eating habits.  
What I am going to suggest as far as nutrition goes, is geared towards what I call the everyday life CrossFitter.  Who is that?  That for the most part is us, we are not professional athletes, we are not training for the CF Games, and most of us are not even college athletes.  We are moms, dads, office workers, firemen, pilots and so on.  Don’t get me wrong I still consider us athletes, ones who are training for our everyday life, our unknown everyday life!  
So, all that just to talk about nutrition.  What are our options?  How far should we take it?  How do we get from here to there without failing?  As “everyday life crossfitters” I see that our best choices are as follows; in no particular order: Zone, Paleo, and Zone Paleo.  
Never have we lived in such a time where information is at our fingertips, there is no reason we cannot get all the information we need from the internet, crossfit.com, books or numerous other resources concerning any of these diets.  Here is a very quick watered down version of each.
Zone:  On this diet you can pretty much eat what you want.  There are suggested best, good and bad choices however it is your choice. The Zone (see Enter the Zone by Dr. Barry Sears) refers to portion sizes   and macronutrient ratios. The Zone ratio is 30 percent protein, 40 percent carbohydrates, and 30 percent fat. The Zone Diet uses “blocks,” which refer to certain benchmark portion sizes to save you from doing calculations all the time.  
Paleo:  The Paleo Diet is based on the diet of our human ancestors from the Paleolithic era. The modern interpretation of Paleolithic nutrition includes meat, vegetables, fruit, seeds and nuts. It omits all grains, dairy, refined sugar, soy, and starches like potatoes and legumes.  With Paleo there are no set guidelines for intake ratios or how often to eat.    
Paleo Zone:  Basically follow the exact same guidelines as the Zone, only now you are only allowed to eat off the Paleo menu; meat, vegetables, fruit, seeds and nuts.
I would love to see every one of us following a strict Paleo Zone; however would I suggest it to you if you were new to CrossFit and coming off a lifestyle of eating that which was less than stellar? No, I would not even start you there if you had already a pretty sound diet but had never followed Zone or Paleo before.  Think about it as laying ground work and developing habits.  We do not teach you in foundations the full power clean or the snatch.  We start you with PVC and medicine ball cleans.  We build good habits and ground work before moving on.  The same is true for your eating habits.  
By starting on a Zone plan we are learning to take in proper portion sizes, this may be huge and take some getting used to for a lot of people.  While we are doing this we are still allowing ourselves to have some of those not so favorable foods.  Remember small steps.  This process may take several months to make it a habit and adjust our bodies and mostly our minds to these new portion sizes.
Once we have established this process and are good at proportioning we can start to shift our quality of food to that of Paleo (meat, vegetables, fruit, seeds and nuts).  By doing this in steps and taking our time we are less likely to fail.  
I am not a fan of Paleo without the parameters of the Zone.  There are a lot of reasons that I will not get into, please talk with me if you want some of the reasons.  The main point is that I have all too often seen athletes dive full throttle into a hardcore Paleo diet only to fail and give up.  I want you all to succeed!  

Part II
Back to the most important part, the “Cheat Day”.  There are a lot of ways to go about your cheat day.  A lot of trainers will suggest when you start the Zone for the first time or coming back to it after a long time that you should follow Zone parameters for approx.  4 weeks with no cheat day.  I am not saying this is wrong I just normally would not suggest it to very many.  The idea is in that time it will become a habit and then easier to stick with.  However I think that 80% of the athletes will come back to their trainer and say yea, see here is my log book I followed it to a T.  When in reality they cheated after the 3rd day but were too afraid to admit it.  And now in their head they have failed and they think I will never master this Zone thing.  So first off I don’t care how you decide to set your cheat day.  Some like to make it a whole day event.  From the time they wake up until they go to bed they will eat what they want.  Others will go to the other extreme and only give themselves one meal as a cheat or maybe a two hour window when they can enjoy as much sugar as their body can take.  So what do I care about you may ask?  Make a plan!  Write it down, tell a friend and stick with it.  If you don’t set a goal or make a plan you are already setting yourself up for failure.  If you decide you are going to have a cheat day on Saturday and that Monday through Friday you are going to Zone every meal, do it.  This also gives you something to work towards.  You know if by Thursday you are starting to get that craves, just hold on you are almost there.  You may ask well what if I make it to Wednesday and I cheat at lunch, my friends were eating cookies and I just had to have one.  Who cares, it is not the end of the world!  Think to yourself Damn that was a good cookie; now get back with it until Saturday.  Don’t change your intended goal cheat day, just keep moving forward.  As you gain more success with the Zone parameters you can start tightening up your cheats to smaller windows if you like.  However take into consideration what you are eating, and training for.  Again if you need more clarification or guidance please ask.