Diet and associated nutritional details represent a scientific quagmire for endurance athletes attempting to find a defensible approach to optimal nutrition for their respective sports. Much of the “science” is not science at all, at least by the standards that are accepted in the “hard” sciences. It is clear that the variability and experimental difficulty that is part and parcel of the study of the human body leads to great difficulty in concluding anything of scientific substance from such studies. However, this has not prevented investigators from making many unfounded conclusions and broad general statements that are so rapidly sucked up and widely distributed by the mainstream media and through the (even more distributive) internet. One needs only try to reconcile the polar-opposite (and so-called “science-based”) nutritional recommendations from “camps” as disparate as the “Paleo” tribe to the “Raw Vegan” cult to be convinced that much of what is concluded from current studies is highly suspect. A couple of years ago Spector analyzed the results and conclusions from adult human nutrition studies using rigorous scientific criteria. What he found is summarized in the following quote from his commentary linked above:
“While the methodology to approach the truth in nutrition research has been known for decades, it is often either not followed or scientific data are resisted.”
Ignoring the fact that even Spector can’t help himself but to give diet recommendations at the end of the article (based on some unfounded “Aristotloian”-platform), it seems abundantly clear that one must be quite jaundiced and therefore hypercritical of nearly any nutritional guidance beyond the most obvious and simple (e.g. consuming a distribution of carbohydrates, protein, and fat).
Kris Gunnars attempts to separate the wheat from the chaff (no pun intended) at his blog focusing on those results that come from randomly controlled trials (RCT), a suitable standard for investigations and much superior to anything from observation studies. Unfortunately, there are polarized recommendations lacking nuance and, often, critical review. Much of what is written in these posts is overblown with broad conclusive statements that are not supported by the studies that are referenced. Beware of what you read at Gunnar’s blog. However, I will suggest that a regular read of his posts will expose you some of the studies that have more scientific credibility outside of the clearly defective review system in place for this field. But again, be critical of what you read. For instance take a read of Gunnar’s recommendations for “Top 11 ‘Diet’ Foods That Make You Fat” specifically the section on whole wheat and then compare that advice with what this qualified reviewer of the cult book “Wheat Belly” has to say about the data that supports any endemic issue with wheat, whole or not. This being in addition to Gunnar’s unsubstantiated claims that there is “mounting evidence” that most people are gluten-sensitive. Although Gunnar makes some valid points on some of the 11 “Diet” foods, the post is not clean. He is clearly an anti-wheat cultist.
Recently, the “anti-grain cult” has held up yet another dis-informationist in the form of Perlmutter and his book “Grain Brain”. A reviewer from The Atlantic deconstructs the absurdity that is this book. In numerous exchanges the reviewer (Hamblin) ties Perlmutter into an embarrassing pretzel knot of inconsistency between what he claims and what the studies he quotes actually say. Noted colleagues in the field call the situation “sad”. We need more of this.
Spector’s comments with regard the review process for many adult nutrition studies will likely give you pause as is summarized in the following paragraph from the commentary linked above:
“In 1994, in a revealing editorial, the editors of the New England Journal of Medicine (who have published many erroneous EOS), in an Apologia in response to highly critical newspaper articles, attempted to justify publication of many conflicting (EOS) dietary studies on vitamins as chemo-preventive agents and the whole issue of dietary advice (e.g., butter vs. margarine). Unfortunately, the editors did not claim that the goal of research should be the search for truth using the best available methods. They did not acknowledge the hierarchy of evidence and the great value of well-conceived and executed experiments. The editors seemed unaware that a few clear, convincing, well-conducted trials, when widely disseminated and followed, can change the practice of nutrition and medicine definitively, unlike hundreds of inconclusive studies, especially EOS.”
Even recognized endurance sport “experts” have crossed the line between adhering to the the data (and the frustration associated with not being in a position to actually conclude anything other than an observation) and making unsubstantiated generalized statements that serve no purpose other than confusing the subject and providing mis-information that inevitably ends up broadcast throughout the mainstream media.
Tim Noakes is the latest example. As a scientist, I have always appreciated Noakes’ posture of challenging the status quo as this is what leads to new discoveries and advances in understanding. Generally he has done so with direct, scientific interpretation of the available and reliable data. He consistently shows where the data does not support the conclusions of many studies and how this mis-information is used for commercial gain in many industries (e.g. the energy sports drink industry as outlined in detail in his book “Waterlogged”). With respect to diet, he has, in the past several years, developed a position which asserts that high carbohydrate diets are a primary cause of obesity and type-2 diabetes in the general population. He extolls the virtues of a high fat, low carbohydrate diet in many media outlets including interviews, debates, and podcasts. In each of these that I have read, watched, or listened to he appropriately and repeatedly notes that the low carbohydrate, high fat diet is an important option for those who are “insulin resistant” (IR) or “carbohydrate resistant” (CR). Insulin resistance is the cause of type 2 diabetes and is thought to be a primary underlying path to obesity. What he fails to note is that only a small fraction of the population is IR. According to the US Centers for Disease Control and Prevention (CDC) and the American Diabetes Association (ADA), 26 million or about 8% of the US population has diabetes; of these all but about 1,000,000 have type 2 diabetes and therefore are IR. Of the 25 million with IR about 7 million are undiagnosed. There is another rather nebulous condition called “pre-diabetes” that is diagnosed if one has higher than normal blood glucose or A1c (glycated hemoglobin) levels but not so high as to be diagnosed as diabetes. These individuals are at higher risk to develop type 2 diabetes (i.e. full-blown IR) as they age due to numerous lifestyle choices combined with, in some cases, genetic drivers. Including all of these potential IR individuals, it is estimated that there may be as many as 100,000,000 total IR and pre-IR individuals in the US population. This number is much more meaningful to the average person in the US, i.e. perhaps 1 in 3 either has or could develop IR. This estimate is an upper limit and could be substantially less but is still a large fraction. However, this fraction does not qualify as “most”, at least in my use of the word. If you listen to the following recent interview (where Noakes and a co-author are speaking about their new cookbook based on a high fat, low carbohydrate diet) you would come away with the impression that (and here I am using Noakes words not mine) “most” or “many, many” people are IR and that you, the average viewer, should seriously consider this type of diet. In fact Noakes actually says during this interview that “some athletes will do well on a high carbohydrate diet” at about 4:40 in the interview.
Some?, how about most? Noakes should follow his own advice and be much clearer about the proportion of the population that is IR and state this clearly, i.e. that about 8% of the population is IR and perhaps as many as 25% more could develop IR and that if you fall into this group you should consider a low carbohydrate, high fat diet. Rather he and his co-author make unfounded generalized (not just for IR individuals as his fellow interviewee indicates that he is not IR) claims about increased athletic performance on a high fat, low carbohydrate diet. In another lecture, early on, Noakes refers to the proportion of the population that is IR and that he will get to that later in the talk. He never does but goes on to insinuate over and over again that IR is nearly pandemic; this assertion (or insinuation) is in direct conflict with well-known and definitive statistical data. Why he never gets back to speaking to the proportions of the population that he is addressing, is concerning- that even “Thorough Tim” has become a cult zealot.
Curiously, and with great disappointment, I find this whole situation to be very similar to the dis-informational and anti-scientific behavior that Noakes himself complained about with respect to the energy sports drink industry in “Waterlogged” – an entire 300+ page book where he repeatedly admonishes scientists in that industry for such behavior. Once again, be very critical about what you read, hear, and view, independent of the past reputation of the source.
Although these are strong statements and it is unfair to lump all investigations and recommendations into a singular group, it is incumbent upon the scientists in this field to increase the standards for publication, not allow unfounded generalized claims to seep into the “reviewed” literature, and to do whatever is possible to ensure that mis-information that inevitably gets distributed by the mainstream media is dispelled and corrected. Although there have been exceptions, in the “hard” sciences (remember “cold fusion”- the curious finding that seemed to be only replicable in Utah and, with great embarrassment to the institution, once at Stanford?) non-critical or a-critical reviews spell death to any Journal publishing such drivel and any scientist making unsupported broad claims is derided. Concerning Noakes, what he is crusading for is fundamentally sound- those with IR (or pre-IR) should be looking closely at their diet and evaluating if a low carbohydrate, high fat diet works for them. But he really needs to be clear that this advice pertains to no more than about 30% of the general population- not “most”. In addition he needs to eliminate any reference to unsubstantiated increased athletic performance in the general population due to a low carbohydrate, high fat diet. There is no currently published, definitive data that supports this statement. Leave the anecdotes at home.
I am looking forward to reading Fitzgerald’s upcoming book, “Diet Cults” , that should be out in May 2014. Hopefully the book will help inform about the consistent lack of support, in scientific studies and even in observation studies, for many of these “diets” being hawked on unsuspecting, gullible, and lemming-like consumers.
9 February 2014 update:
Gary Taubes wrote an opinion piece for the New York Times which was published on 9 February 2014. His view of the generally low standards for publication and dissemination of Nutrition information and the paucity of reliable, high quality research in the field of Nutrition is nearly identical to that I am presenting here. Whilst Mr. Taubes and I do not agree on the degree of the negative effect of sugar and grain consumption on non-IR individuals, we fully agree on the lack of quality science in Nutrition science.
“Racing Weight” by Matt Fitzgerald
So where to turn? For the overwhelming majority of athletes that are not IR or pre-IR is there a sensible, supportable path forward?
One approach, at least for endurance athletes, is to take an “outcomes-based” perspective and look to what successful endurance athletes consume and combine this with the meager valid data that nutrition science can reliably provide to give some semblance of guidance for a diet and nutrition plan. Numerous authors of nutritional advice have taken this approach but the best, in my experience, is that of Matt Fitzgerald. His thoughts are well presented in his book Racing Weight, now in a second, updated edition. Although the title might lead one to conclude that the book is focused on attaining and maintaining a “racing weight”, there is much more. From outlining the reasons that weight is very important to optimal endurance performance to energy source balance to a review of what a broad spectrum of successful endurance athletes eat, this book is a source of guidance on most of the important aspects of serious training for endurance sport.
The “outcomes-based” approach is what resonates here. In the absence of definitive science (and in the overwhelming presence of a profusion of commercially-driven hyperbole) looking to the make-up of the diets of successful endurance athletes is very logical. What Fitzgerald has found is that by and large these athletes eat a high carbohydrate (>60% of total calories) diet of high quality ingredients. No single “diet” is represented in the review, rather a wide range of approaches to the same end is observed:
“For example you will see a lot more vegetables than sweets in the food journals of the best endurance athletes-proof that a high-quality diet is required. But you won’t see many named diets (Paleo, Zone, gluten-free, etc.) at this level-proof that all food types and a variety of ways of eating are allowable in the pursuit of racing weight.”
Fitzgerald has put a generalized structure around a process that will efficiently and effectively allow one to identify, work towards, attain, and maintain their racing weight. This includes six steps (or actions) most of which any serious athlete already does. What is helpful is that these actions are structured and supported by both observed results with successful athletes in endurance sport and by what nutrition science is available. As an endurance athlete for over 35 years, I have come to realize that much of the guidance given here is very much what was provided by US and other national team endurance sport coaches and nutritionists at least as far back as the 1970s. What has happened in the meantime is the rise of nutrition advice for commercial gain in the guise of “the latest science”. As a result we are offered single diet “solutions” with polarized, refractory “rules” that have little or no support in either what reliable scientific literature is available or in any broad-based, time series survey of outcomes with athletes involved at high levels of competition.
One point that Fitzgerald consistently makes is that although he is providing a structure for going forward toward an optimal racing weight, any specific program based on the structure will be unique to the individual and represent just one of the many ways to attain this goal. There is no recipe- a focus on feedback and the use of the tools provided in the text allow one to design, and modify as needed, an individual program that suits their training and lifestyle needs.
Some of the guidance that has impacted my diet includes reinforcement of the use of whole grains to maximize vitamin and mineral content, putting some numbers on carbohydrate needs as a function of training time, and specifics with respect to “nutrient timing”.
Fitzgerald’s basic guidelines are broken down into needs for carbohydrate, protein, and fat for endurance athletes. For each recommendation he reviews what studies have found with respect to each macro-nutrient and maps this information on to the experience of successful endurance athletes. Importantly, Fitzgerald also does not subscribe to any sort of generalized macro-nutrient “proportioning” as is commonly found in many athletic performance diet recommendations. There is no 40-30-30 or 60-20-20 “rule”, in fact he has, in the revised edition presented information in a way that will prevent a direct calculation from the book. He does this by never giving a recommendation for fat intake, asserting that the fat will be what ever it is by following his guidelines for carbohydrate and protein intake and making a preference for Omega-3 fats over Omega-6 fats. This will be discussed more completely below.
Use of the Book and Diet Analysis
To evaluate the efficacy of the guidance provided in this book, I followed the generalized structure, kept track of my diet, and coincidentally embarked on the Nordic Ski racing season. There are not a plethora of races in Nordic Skiing as there are in running so one tends to do the same races every year. This allows for year to year comparisons, not so much of race time since the snow conditions play such a large role in skiing speed, but of “race feel”. In addition, in-season training can also be contrasted. This effort was nucleated by my coach suspecting that my weight was too low and that I was compromising my ultimate ability to attain optimum performance. At a running weight of 125 lbs and a Nordic Skiing weight of 130 lbs (the approximately 5% increase in weight during Nordic Ski season is due to substantial required upper body muscle mass to be competitive), my BMI ranges from 19.6 to 20.4 and was considered by my coach to be marginally low. The supposition is that although a low weight is advantageous for energy use reasons, in endurance sport it is important to have significant and readily available energy sources to allow for high quality hard training efforts, optimal competitive performance, and most importantly, optimized recovery and muscle repair. As indicated in a previous post, as I ramped training back up two years ago I had dropped to 1-a-week interval sessions from a long-standing past regimen of 2-a-week interval sessions due to an inability to fully recover and be able to maintain the quality of over-distance (OD) (skiing), long runs (running), and tempo (skiing and running) sessions. I chalked this up to age as supported by Friel in his summer 2013 series of posts on training for 50+ individuals. My coach disagreed and has encouraged me to analyze and adjust my diet to ensure that I have consistent and sufficient energy system replacement. We have also scheduled, and have continued for the past two months, training plans with 2-a-week interval sessions. So far so good, and I think that the diet analysis and tracking has helped ensure sufficient energy levels to keep with the regimen. I have been more than able to handle the two-a-week interval sessions and I can see (from pace data) and “feel” that I am getting stronger and faster. In addition my ability to “crest” hills/mountains with deep efforts and keep going hard has improved substantially. I have not felt this level of endurance strength since my long-ago days as a Cat 1 road cyclist. It feels great!
Although having just started this analysis and some associated diet “adjustments”, early indications are that the advice given in the book are sound- at least for me. The focus has allowed me to “clean-up” an otherwise pretty good diet and sharpen the details to ensure robust energy balance, with some positive, early results noted above.
I had not analyzed my diet in many years (like about 25 years) so it was interesting to have more insight into what I was now eating and how this was shaping my body. In the same analysis period I also started to cook some recipes from Fitzgerald’s latest companion book to “Racing Weight” called “The Racing Weight Cookbook” (I will be posting a review of this book soon). My diet in the analyzed period did not change much from what was normal for me but I did include more whole grains, a bit more vegetables, and a sharper eye to the nutrition quality of ingredients, and most significantly, more carbohydrates. I have always “cooked from scratch” and seldom consume highly processed ready-to-eat foods. An expert would describe my diet as “Mediterranean”- such a diet is nicely analyzed in contrast to a “paleo” diet in this series of blog posts- 1, 2, 3 by an author who I think does a great job of collecting data and writing “position posts”.
We (my wife and I) seldom go out to restaurants either. Early in our marriage, I was a “sports-widower” for 9 years when my wife was on the US National and Olympic teams and competing internationally. As a result she was spending less than 6 months per year at home. Going to a restaurant alone is not a great experience in general, so in this period I took a number of cooking courses from both culinary arts teaching professionals and operating chefs. This laid the groundwork for being confident in cooking all sorts of foods utilizing a broad spectrum of techniques. I have found, when we do go out, that, with some exceptions, I can do better with better ingredients at home- and be certain of the quality of the ingredients and the methods used for cooking. The investment in a rudimentary cooking education has been well worth the time and expense. Although going out to restaurants can be fun and interesting, I will suggest that, for endurance athletes, you will be best off too make such occasions the exception rather than the rule as it will allow for more control and mindfulness with respect to your diet.
Keeping consistent track off your diet is no small task. However, a broad spectrum of resources on the internet have made this much easier, particularly compared with what I had to do for such an analysis back in the late 1970s and early 1980s. Then you had to have one of those 5 inch thick food encyclopedias and manually look up each food type and macro-nutrient proportions. Now you can just put the food type in Google and there will be dozens of sites with the information that you need within seconds. Some of these even have granularity down to brand name and cooking method. So reliable estimates can easily be made on whatever you are eating. Great! One caveat: many of the reported caloric contents do not account for soluble vs. insoluble calories. The data reported are based on “burn” results which account for all calories in the food, insoluble and soluble. So some of your calorie data from these sources will be a bit high, but the overarching importance of this exercise is to become calibrated with what you are consuming and what it is approximately composed of. These data will give you perspective that one cannot obtain any other way.
One of the basic points made by Fitzgerald is that there is a relationship between the magnitude of carbohydrate consumption and how much training you are doing- the more you train the more carbohydrates you need to consume. His chart of recommended carbohydrate intake per pound of (goal) body weight per day is as follows:
So, for my goal weight between 125-130 lbs and 12-15 hrs/week of training (600-700 hours per year), I should be consuming between 475 and 520 grams of carbohydrate per day. That’s almost 1.2 pounds of carbohydrate per day! – as you will see below, that is a lot of carbohydrate even though I am relatively light. These values are derived, as far as I can tell, from energy use considerations making a bunch of assumptions on specific body efficiencies, training intensity, and and other “energy use” details. I would have liked to see a much better presentation of the basis for these recommendations, independent of the analysis of the diets of successful endurance athletes- this is a failing in this book. Although Fitzgerald does not address this, it is obvious that there is likely to be a significant variance in person-to-person needs and that the values in the table are starting points, not absolutes.
As far as protein intake recommendation, Fitzgerald centers on a value of 1.2 gms/kg of (goal) body weight. For me that means about 68-70 grams of protein per day or about 0.20 lbs of lean protein- a very small amount in comparison to the typical athlete diet.
Fat is not addressed numerically, rather, as noted above, recommendations are given to switch as many Omega-6 fats to Omega-3 fats as one can. This will involve eating more fish and/or taking fish oil supplements. I’d much rather eat fish!
Time Series Data
I tracked my diet for about a month and this gives a good baseline understanding of what you are eating and exactly how much of each of the macro-nutrients. There were surprises along the way including realizations of how calorically dense some meals are, how few calories I consumed on some days, and that I am no where near Fitzgerald’s recommendation on carbohydrate intake.
Presented below are time series data for total daily calories consumed, macro-nutrient distribution in gram weight consumed (red- carbohydrate, green- protein, and violet- fat), and macro-nutrient distribution in percentage of total gram weight consumed (blue- carbohydrate, red- protein, and green- fat).
Outputs and Directions Forward
So what can one take away from this sort of analysis? Here is what I am focusing on:
- My carbohydrate intake is well below the recommended level. Fitzgerald argues that if you do not keep this intake up you will not have sufficient energy to ensure optimal training, performance, and recovery. In discussing this with my coach, a two-time endurance Olympian, she indicated that she and her teammates would also have difficulty in keeping the carbohydrate intake up, particularly when seasonal training hours climbed up to the 30+ hrs per week level. She recalls sitting at OTC and National Team training camp dinner tables “stuffed” and still needing to eat another potato, etc. Yet with this high carbohydrate diet, they, by-and-large (meaning those that actually made it onto the Olympic team), were becoming more and more lean, strong, and faster as a result of being able to handle the intense and hard training sessions. Action: attempt to increase carbohydrate intake and monitor interval and tempo sessions for higher TRIMP, faster paces, and increased recovery.
- My total calories consumed are marginally low for calculated caloric needs. Using a number of approaches, I determined my Basal Metabolic Rate (BMR) to be about 1500 calories per day. Add to that an average training session of 1000 calories and numerous other activities that I take part in on a daily basis (like a daily 3 mile bike ride to and from the grocery store- year round (with studded snow tires in the winter)). With all of these activities tallied, the daily total comes up to about 3000-3500 calories a day. As you can see I seldom even get above 3000 calories, so I am apparently operating on a average daily calorie deficit. Action: bump up the average daily caloric intake from 2500 to 3000 and monitor weight and training outputs to ensure that unneeded weight is not being added.
- Based upon Fitzgerald’s recommendation, my protein intake is high- about 25% high. This, combined with #1, means that I should replace protein intake with carbohydrate intake at about 25 grams per day at the 2500 calorie per day baseline (so a bit more at the 3000 calories per day goal). Action: replace protein calories with carbohydrate calories at about 30-35 grams per day.
- I feel fine and have plenty of energy for the training sessions at 12-15 hours per week. In the past month I have had two bouts of the initial symptoms of a viral cold (usually in the throat). Both times I have fended this off without any downtime but it may be an indicator of “edgy” nutrition, calorie and vitamin-wise. Perhaps I would have even more energy and be more robust to viral attack if I were to increase my caloric intake and nutrition quality. Action: monitor energy level and susceptibility to viral infection as a function of increased caloric intake.
Diet and the effect of diet on endurance athletic performance is one of those ephemeral, difficult-to-define things that can affect activities that are significant time and effort investments for many aspiring athletes. Yet very little, clear, concise, and results-based advice is available to the average participant. Matt Fitzgerald has provided in his book “Racing Weight” a reasonable, “outcomes-based” approach that is a very good place to start in one’s search for a diet and training regimen that works to enable optimal endurance athletic performance. Even if one ends up with a diet and nutrition protocol that is very different from the type described in this book, she/he will be well served by what they will learn by going through the analysis and trying the tenets of Fitzgerald’s recommendations. The fact that these recommendations are based on the diets of a wide range of successful endurance athletes should hold a certain amount of credence as to the efficacy of the approach and the likely results that a non-IR, committed athlete might achieve. I highly recommend “Racing Weight” as a grounded, results-based account of good nutrition for endurance competition.