CBL Prep Phase and CNS are metabolic disasters for people that Crossfit

7 Apr

One of the topics that comes up often is that in the book Carb Back Loading John Kiefer has an optional “prep phase”.  The prep phase basically consists of a 10 day period where you would eat less than 30 grams of carbohydrate for ten days straight.  The idea being to clear your glycogen stores as much as humanly possible.  It’s pretty much the same idea as John’s other book Carb Nite Solution, it’s a $19.99 book, supposedly CNS is what you would use for fat loss and Carb Back Loading is what you would use for muscle gaining.  Assuming of course that you are either a relatively sedate individual or someone that is not particularly active.  Does that sound like someone that does Crossfit? It doesn’t.  Ultimately my website is a business, I sell the $53 dollar book instead of the $19.99 book.  That should tell you something right there, don’t you think I know people would rather by the cheaper book that specializes in fat loss? The simple fact is that diet is not a good fit for highly active people. Let me say this in terms that can’t be mistaken, a person that does Crossfit eating under 30 grams of carbohydrate is probably harming themselves.

Then why is it even mentioned in the book

Firstly Kiefer says in the book that if you do HIIT training you can take 3 days off of the 10 day prep phase.  Crossfit is essentially HIIT training every single session! Couple that with the fact that most of the people I am talking to are already under eating carbohydrate AND THEN ALSO under eating as it relates to their performance level.  For a lot of people this has set up a scenario where they have plateaued and are looking for solutions.  So my message of eating appropriate amounts of foods coupled with a reasonable amount of carbohydrate has resonated.  Then people hear about the prep phase reading CBL and they want to snuggle back up to their old friend the low carb diet.  Right, because the eat less do less diets were serving them so well in the past.

The reason why Kiefer puts the prep phase out there is because his initial target audience was already eating carbohydrate inefficiently and in a lot of cases over eating them.  Unless you have been doing the standard american (S.A.D.) diet that probably isn’t you. Some of the arbitrary numbers related to body fat percentage probably don’t apply to you because your body composition issues are not likely similar to the average person over eating carbs that is mostly power lifting or body building (relatively low intensity activity).

Your repressed metabolism

I talk often how very low carb diets repress metabolism, compromise fat mobilization and can lead to thyroid issues as a result.  Couple that with under eating and Crossfitting and you have what the Suppversity Blog refers to as the “Athlete’s Triad”.

The goal of this site

Initially my goal was to explain to people how they can eat reasonable amounts of carbs and that no foods are inherently bad foods.  It didn’t take long to realize a lot of people were chronically under eating and so we started working on both of the issues.

“Should you workout during the prep phase”

That is the title of this video from Kiefer, if he is asking this question some alarm bells should be going off in your head. As I mentioned above he mentions HIIT training and how it dramatically alters the time needed for the prep phase. When Kiefer refer’s to heavy duty or “intensity” he is not referring to Crossfit, he is referring to lifting heavy weight in a fashion similar to Wendler’s 5-3-1 or some 5 x 5 plans.  These programs have significant rest built into the workout.  If you watch this video and still come away with the idea that you should Crossfit and very low carb then I am not really sure anyone can help you.

At the very least I hope this addresses the question once and for all of why I don’t recommend the prep phase for people that do Crossfit.

2 Responses to “CBL Prep Phase and CNS are metabolic disasters for people that Crossfit”

  1. Marcee April 7, 2013 at 3:17 am #

    I’m just confused! I am halfway through the book and still don’t understand if you believe that this Carb-Back-Loading will work for crossfitters? It seems that the author says it won’t but then why would you be promoting the book? Sorry if its a dumb question, I just am not clear..

    • Paul Nobles April 8, 2013 at 12:18 pm #

      It’s the only book I sell on a Crossfit blog, so it works but there are adjustments that need to be made for us. Is Kiefer saying Crossfitters shouldn’t eat carbs, no he is not. So the question ultimately becomes how many. That is what we walk you through using the science lab. If you just use the book, you are right, it will be confusing.

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