The Zone and Athletic Performance
By Robb Wolf | August 12, 2009
Amidst yesterdays comments the question was asked “Where is the science for the Zone or paleo with regards to improving athletic performance?” as both a scientist and coach I would have normally told this person to go pound sand as my gym is full of people who are performing FAR better with a paleo diet than the standard high-carb, low-fat chow. The reason this person hooked me in however was because they cited a paper that I had already written a rebuttal to for the CFJ. I’m not really game for a re-write to get that piece up to CFJ standards so I’ll just post it here today. A point I’d like to make here that I did not make in the paper is asking for “science” in many instance is like asking for the answer to every question imaginable all at once. Bright-eyed, bushy-tailed undergrads who hear their prof’s say “it must be scientific!” have not hit the real world yet and do not realize the complexity of designing a study that tells you something meaningful vs. just being a means to your next grant. As I make the point below, no one bothered to look at how the Zone has been used with ATHLETES. Instead the guidelines from the weight-loss book were followed, with predictable results. The following is the content of that article:
I received an interesting email several weeks ago that contained a blog post recommending AGAINST the Zone nutritional approach for individuals entering BUD/S or similar, highly demanding selection programs. The author makes his case against the Zone in three basic ways:
1-The Zone is counter to standard endurance nutrition “wisdom”.
2-Scientific investigations of the Zone have produced lack-luster results.
3-The supposed scientific underpinnings of the Zone are inaccurate and thus, the Zone’s efficacy must be called into question. To properly consider the author’s position, let’s take a look at his blog post in it’s full glory:
“Nutrition is a very important factor regarding preparation for SEAL or SWCC selection. Preparation requires proper training, and proper training requires proper fuel selection. It is essential to develop an effective eating strategy to make it through such a physically demanding program as BUD/S, which means learning to eat like an endurance athlete (emphasis mine). SEAL candidates are exposed to nutrition information at the Prep Course in Great Lakes, during BUD/S Orientation, and during SQT – but it’s never too soon to get a handle on nutrition.
Many candidates have heard that the Zone diet is an effective diet to use while preparing for BUD/S. Unfortunately, this is not true and BUD/S candidates are not encouraged to follow the Zone diet. The Zone diet is not considered to be unhealthy, and has been used with good results by people attempting to lose weight. Even for moderately active people or athletes who do not train hard for more than an hour a day, the Zone diet may serve their needs. The problem is that strictly following the Zone diet (40/30/30 per cent of calories from carbohydrates, proteins, and fats) does not provide enough fuel in the form of carbohydrates to support the amount of training necessary to prepare for BUD/S (or get through BUD/S!) The Zone diet has been very effectively marketed, but claims are made based on anecdotes and testimonials (emphasis Caviston), not scientific research. Note: for those who use energy bars or other commercial energy foods, Zone products are fine, though not proven superior to other brands. The caution against the Zone diet is the practice of limiting carbohydrates to 40% of total calories.
Here is a link to an article in the Journal of the American College of Nutrition called “The Zone Diet Phenomenon: A Closer Look at the Science behind the Claims”. From the article’s conclusions: “When properly evaluated, the theories and arguments of popular low carbohydrate diet books like the Zone rely on poorly controlled, non-peer-reviewed studies, anecdotes and non-scientific rhetoric. This review illustrates the complexity of nutrition misinformation perpetrated by some popular press diet books. A closer look at the science behind the claims made for the Zone Diet reveals nothing more than a modern twist on an antique food fad.”
This link is to the abstract of another article in Sports Medicine called “The Zone Diet and Athletic Performance”. The entire article is unavailable without subscription, but the following portion is relevant: “Applying the Zone’s suggested protein and macronutrient distribution in practice, it is clear that it is a low carbohydrate diet by both relative and absolute standards, as well as calorie deficient by any standard. Reliable and abundant peer reviewed literature is in opposition to the suggestion that such a diet can support competitive athletic endeavors, much less improve them.”
I’d like to keep this counter point fairly simple however there is SOME need for technicality. As we will see, if we simply hang our hats on “inputs and outputs” it could be quite easy to dismiss the Zone as a dietary approach which is inadequate to the needs of elite level athletics or for the rigors of various selection programs. First I want to look at the notion that the Zone is NOT appropriate for endurance athletes and the statement on the author’s part that BUD/S candidates should emulate the eating habits of “endurance athletes”. I will then look at the scientific investigations of the Zone and illustrate some laughably simple design flaws, and finally I’ll look at the notion that the Zone is “unscientific” as seems to be implied by the references supplied by the author.
What DO endurance athletes eat?
The author recommends that individuals who wish to succeed at BUD/S should “…learn to eat like an endurance athlete”. The seems like sound advice until one realizes there is NOT solid consensus in what that actually means! One might assume this to mean an exceptionally high carb, grain based diet and in fact this does reflect the diet of many top endurance athletes, but by no means does it reflect ALL endurance athletes. In particular several of the worlds best regarded, highest paid and most successful endurance coaches employ nutritional strategies quite consistent with the Zone. Joe Friel who has authored more than 10 endurance oriented books including: The Triathletes Training Bible, The Cyclists Training Bible, and the Paleo Diet for Athletes (co authored with Prof. Loren Cordain) has coached athletes at the Olympics and World championship level, and was founder and past Chairman of the USA Triathlon National Coaching Commission. Joe is quite successful and highly sought after for his coaching not only of the technical elements of training but also for his nutritional approach. What IS that approach? A moderate carbohydrate, grain-free paleo diet sliced and diced into approximately 30% protein, 30% fat and 40% carbohydrate. Joe DOES alter fueling somewhat during races and to emphasize post workout recovery, but his basic approach is quite at odds with what Caviston seems to imply. Here is an excerpt from the Paleo Diet for Athletes in which Joe describes his experience switching from a standard high carb, low fat, grain based diet to a paleo/Zone diet:
“I have known Dr. Cordain for many years, but I didn’t become aware of his work until 1995. That year we began to discuss nutrition for sports. As a longtime adherent to a very high-carbohydrate diet for athletes, I was skeptical of his claims that eating less starch would benefit performance. Nearly every successful endurance athlete I had known ate as I did, with a heavy emphasis on cereals, bread, rice, pasta, pancakes, and potatoes. In fact, I had done quite well on this diet, having been an All-American age-group duathlete (bike and run), and finishing in the top 10 at World Championships. I had also coached many successful athletes, both professional and amateur, who ate the same way I did.”
“Our discussions eventually led to a challenge. Dr. Cordain suggested I try eating a diet more in line with what he recommended for one month. I took the challenge, determined to show him that eating as I had for years was the way to go. I started by simply cutting back significantly on starches, and replacing those lost calories with fruits, vegetables, and very lean meats.”
“For the first two weeks I felt miserable. My recovery following workouts was slow and my workouts were sluggish. I knew that I was well on my way to proving that he was wrong. But in week three, a curious thing happened. I began to notice that I was not only feeling better, but that my recovery was speeding up significantly. In the fourth week I experimented to see how many hours I could train.
“Since my early 40s (I was 51 at the time), I had not been able to train more than about 12 hours per week. Whenever I exceeded this weekly volume, upper respiratory infections would soon set me back. In Week Four of the “experiment,” I trained 16 hours without a sign of a cold, sore throat, or ear infection. I was amazed. I hadn’t done that many hours in nearly 10 years. I decided to keep the experiment going.”
“That year I finished third at the U.S. national championship with an excellent race, and qualified for the U.S. team for the World Championships. I had a stellar season, one of my best in years. This, of course, led to more questions of Dr. Cordain and my continued refining of the diet he recommended.”
“I was soon recommending it to the athletes I coached, including Ryan Bolton, who was on the U.S. Olympic Triathlon team. Since 1995. I have written four books on training for endurance athletes and have described and recommended the Stone Age diet in each of them. Many athletes have told me a story similar to mine: They have tried eating this way, somewhat skeptically at first, and then discovered that they also recovered faster and trained better.”
There are many points to be learned from Joe’s experience switching from the standard high-carb, low-fat, grain based diet to a Paleo/Zone diet. I’ll get to all those points in due order but the primary point which must be made at this point is that Caviston’s recommendation to “learn how to eat like an endurance athlete” may in fact be true, however it illustrates the need to question whether Caviston actually knows what that MEANS. Elite level coaching is quite far afield from the world of special operations military in a very important point: Coaches are paid based on their success, special operations communities succeed often times INSPITE of their training. In a scenario like BUD/S and SQT there is a supply of highly motivated, driven individuals in EXCESS of need. Given this fact one need merely apply sufficient pressure to weed the herd to sufficient numbers for the current needs. Coaches by contrast live or starve based on the results they achieve for their PAYING clients. Joe Friel and an ever-growing number of coaches at the elite level understand that the high-carb, low-fat diet is NOT the best route to optimum performance, to say nothing of health and longevity. A pithy counter point to Joe’s story and his success with his athletes would likely run along the line: “This is just anecdotal information…we need SCIENCE to show us the way…” As a former research scientist I can see both the wisdom and the fantasy inherent in this sentiment, but since Caviston brought one “scientific” study looking at the Zone in an athletic performance setting we certainly need to address those findings and learn a little about the limitations of Empirical findings devoid of technical understanding.
Blinded by Science
The research Caviston mentions above and the research presented here illustrate a problem with how the Zone has been presented. Dr. Sears has largely neglected to inform the research community that there are effectively TWO different approaches to the Zone. One is a calorie restricted weight loss diet, the other is a eucaloric diet which is moderate in carbohydrate and protein, higher in fat and perfectly suited to the needs of athletes. This lack of education on Dr. Sears part (in my opinion) has made it difficult for what little research which has been directed at the Zone to have any meaning. In the above examples the researchers were subjecting athletes not only to dramatically reduced carbohydrate intake (an issue we will look at in a moment) but also to INADEQUATE calories! We should be shocked if a group of athletes did anything other than perform poorly when they have their primary fuel source changed AND are inadequately fed! To fully understand this situation we need to look at exactly WHAT happens when we feed athletes little to no carbohydrate but ADEQUATE calories. This is actually a much more extreme dietary alteration than the Zone recommends but looking at the metabolic adaptations to different fuel sources will provide a much better perspective for accurately accessing the relative merits of the Zone. This exercise also illustrates an inherent flaw in a purely Empirical approach to fitness and actually, life. If we took the above information at first blush we should, by the laws of empirical observation, categorize the Zone as a performance DAMAGING diet when in fact it is not. Without SOME understanding of human metabolism, origins and the time-course of adaptations to various fuels, we could easily jump to the wrong conclusion.
In this article from the Journal of Nutrition and Metabolism the author reviews the information surrounding the effects of a ketogenic (very low carbohydrate diet) on performance. It is an interesting piece in that it shows historical accounts of investigations into low carbohydrate diets as well as modern metabolic ward studies comparing athletic performance with or without significant dietary carbohydrate. An immediate and compelling finding is that CHANGING from a high carbohydrate to a low carb diet leaves one feeling weak and showing poor performance for as long as 3 weeks. This mirrors Joe Friel’s observation that his training and recovery took a significant hit for the first 3 weeks of his change to a Paleo diet. What we discover is that it takes 3-4 weeks for the fat mobilizing enzymes used during exercise to build to sufficient levels to off-set the low carb diet. Near the end of the Nutrition and Metabolism paper we find an interesting summary of the findings:
“Both observational and prospectively designed studies support the conclusion thatsubmaximal endurance performance can be sustained despite the virtual exclusion of carbohydrate from the human diet….Therapeutic use of ketogenic diets should not require constraint of most forms of physical labor or recreational activity, with the one caveat thatanaerobic (ie, weight lifting or sprint) performance is limited by the low muscle glycogen levels induced by a ketogenic diet, and this would strongly discourage its use under most conditions of competitive athletics.”
Boldings were my emphasis.
What we can draw from this is that fairly high level aerobic activity may be carried out in a properly adapted individual, even under ketogenic conditions. The need for carbohydrate for sprint/high intensity efforts remains fairly consistent, however this illustrates in interesting phenomena: elite endurance athletes utilize a relatively higher percent of fat for fuel at any given work output vs. less advanced athletes. Other considerations such as reduced inflammation due to dietary alterations undoubtedly play a role in performance and recovery but are outside the scope of this paper. These topics are thoroughly investigated in the CrossFit Nutrition Certification.
What can be safely inferred from this information is a moderate carbohydrate intake, coupled with adequate time to adapt to fat as a primary fuel source, is a viable alternative to the standard high carb, low-fat approach. Not only is it viable as a means of athletic fueling, it is obviously a better option for long-term health and wellness.
The final point I will address is the link Caviston provided which attempts to discredit the Zone by tackling perceived inconsistencies in the science Dr. Barry Sears uses to describe how the Zone works. The paper Caviston uses to this end is quite technical so I will keep my point brief: The authors of that paper inaccurately characterize the claims made by Dr.Sears. The authors imply Dr. Sears describes “good” or “bad” eicosanoids (hormone like molecules which have powerful effects in the body) as all or nothing propositions when this is simply not the case. Dr. Sears makes it clear that he is making some broad generalizations to simplify a VERY complex chunk of information. He does this in a way that conveys the essence of what people need to know: Insulin control + omega 3/omega 6 fatty acid balance= optimized health and performance.
I’m not sure if Caviston’s position on the Zone is legitimately one of ignorance or this is simply the latest in a trend of standing against anything that CrossFit recommends. It is intriguing to me when any organization or individual dogmatically defends what is ultimately an indefensible position. Professor Loren Cordain made the following observation:
“1) If, in human networks, the nutritional message is incorrect or partially correct, then 2) the message will eventually fail and fizzle out because it simply doesn’t work in the majority of people , or 2) If, in human networks, the nutritional message is indeed correct in the majority of people then, 3) people will find it and will adopt it (whether or not they are able to sustain it), and pass it on. Herein lies the beauty and power of this concept — success breeds success.”
This observation offers significant insight in why CrossFit has gained rapid and lasting acceptance in a variety of communities: It works. The training, the nutrition, the whole enchilada. Over time our understanding of this technology will grow and our ability to help people and affect change will grow in lock-step with this progress. For those who find themselves drawn towards the rigors of BUD/S or a similar highly competitive selection program I can unreservedly recommend a paleo/Zone approach to optimizing performance and increasing one’s likelihood of passing a given program. Hopefully however it is obvious that a period of 3-4 weeks may be necessary to fully adapt to the program, so proper care and planning should be taken when contemplating a significant nutritional change.
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