Low Carb vs high carb arguments.
Dr. Volek 101
For anyone unaware, Jeff Volek is one of the world’s most prolific & influential low-carb diet researchers. He’s an associate professor at the University of Connecticut (full bio here). He’s also one of the authors of the latest installment in the Atkins bestseller saga, New Atkins for a New You. Many consider him to be the top guy in this area of study. When I agreed to debate a low-carb advocate, I had no clue who’d end up on the other side of the cage. When I got word that it was THE Dr. Jeff Volek, imagine my excitement as someone who has been intrigued by his work since the late nineties. I’ve always viewed him as the “Rebel RD.” This is because about 10 years ago when his name started regularly appearing in major magazines, he was the only registered dietitian who openly endorsed low-carb/ketogenic dieting. The rest of the low-carb RDs – if they existed at all – were afraid of reproach by the American Dietetic Association.
Volek’s Case
The topic was carbohydrate intake for athletic performance (and to a lesser degree, health). The planned format was for Jeff & I to present our case (via Powerpoint) for 15 minutes each, leaving another 20 minutes for free-flowing discussion and audience Q & A. So, it was more like a point/counterpoint thing than a traditional debate. Jeff went first and ran about 10 minutes over his limit, then I went on for a slightly shorter period. There was no time left for discussion since the whole affair was less than an hour before we had to clear out of there for the next presenter. So, only 50 minutes for a debate between Volek and Aragon? Yes. But it was an action-packed 50 minutes, that’s for sure. I’ll do my best to sum it up as follows.
Jeff began by discussing the problem of endogenous fuel stores in the context of endurance competition. While we only have roughly 1200-2000 kcals of glycogen, we’ve got at least 40 times that amount of energy stored in the adipose tissue. So, why not train the body to become adept at tapping into this nearly bottomless well of energy we carry around like designer luggage? Jeff then discussed the physiology of carbohydrate-mediated insulin elevations acting as a brake on fat mobilization & oxidation during exercise. He then illuminated the erroneous conflation of a relatively benign condition he calls nutritional ketosis with an adverse condition called ketoacidosis. He drove the point that ketosis has gotten a bad rap, and that ketones are a perfectly viable fuel source for not just brain functioning in the absence of exogenous carbohydrate availability, but also to support endurance capacity.
He then discussed research by Phinney et al [1], claiming a maintenance of endurance capacity in well-trained cyclists despite 4 weeks of a ketogenic diet for the purpose of inducing “keto-adaptation” – a physiological shift towards more efficiently deriving energy from ketones and fat. Jeff proposes that “hitting the wall” due to glycogen depletion in endurance competition can be avoided once an athlete becomes keto-adapted (also referred to as being fat-adapted), and thus more able to tap into stored fat for fuel. He also discussed a study where overweight/obese subjects on a resistance training program lost more fat on a low-carb diet than a low-fat diet [2]. I challenged Jeff on the methodology of this study when he brought it up again in the second lecture – more on that in a bit. Jeff concluded his lecture by contending that a growing minority of endurance competitors have successfully employed the low-carb approach, and that he’s not the only guy challenging conventional wisdom. To my amusement, he chose to use Tim Noakes’ recent (and rather dramatic) low-carb epiphany as evidence that he’s not alone on this.
My Turn
The aim of my presentation was to present controlled research, observational research, and client case studies collectively showing that the narrow position of low-carb supremacy simply does not hold much evidential weight. I began by discussing the current state of affairs in the low-carb versus low-fat experimental research, which is best summed up in a recent meta-analysis by Hu et al (the largest of its kind) showing a general lack of difference in effectiveness for improving metabolic risk factors, including weight reduction [3].
I went on to examine the common methodological limitation of low-carb versus low-fat comparisons failing to match protein intake. As such, the advantage of greater thermic effect, satiety, and lean mass retention will strongly favor the groups whose protein is optimized, or at least adequate. Low-fat/high-carb treatments often fall short of adequate protein intake, and the disadvantages are inherent. A memorable example showing significantly greater effects on mood and a lack of significant difference in body composition improvement from a non-ketogenic diet compared to a ketogenic diet was by Johnston et al [4]. This study showed a trend toward more favorable effects in the non-ketogenic diet group, and the important detail is that protein intake was similar between groups, and significantly above the paltry RDA level.
It was serendipitous that Jeff brought up Phinney et al’s 1983 study on highly trained cyclists [1], because I was well-prepared to expose its details. This study involved 5 subjects who, after 1 week on a conventional diet were put on a ketogenic diet for 4 weeks. Both phases were eucaloric (weight-maintaining). By the end of the 4 weeks, the subjects’ steady-state respiratory quotient (RQ) dropped from 0.83 to 0.72, indicating that they indeed were fat-adapted. Exclusive carbohydrate utililzation is indicated by an RQ of 1.0 while the exclusive utilization of fat is indicated by an RQ of 0.7, so with an RQ just a hair above that, these subjects were thoroughly primed for the proposed benefits of keto-adaptation.
Stick with me now… Pre and post-keto-adaptation endurance capacity (measured by time to exhaustion or TTE) was not significantly different. This lead the authors to conclude that aerobic endurance at 62-64% of VO2max was not compromised by the 4-week ketogenic diet phase. Mean TTE in the non-keto and keto conditions were 147 and 151 minutes, respectively. However, the authors’ conclusion is misleading since 2 of the 5 subjects experienced substantial drops in endurance capacity (48 & 51-minute declines in TTE, to be exact). One of the subjects had a freakishly high 84-minute increase in TTE, while the other increases were 3 & 30 minutes. The outlying high value was instrumental in skewing the results away from any significant decline in the keto condition’s mean TTE.
I proceeded to discuss how 21 years after the aforementioned study [1], Phinney wrote a review in which he reflects upon the ergolytic (performance-compromising) effect of the ketogenic diet phase, stating the following (my bolding for emphasis) [5]:
“The bicyclist subjects of this study noted a modest decline in their energy level while on training rides during the first week of the Inuit diet, after which subjective performance was reasonably restored except for their sprint capability, which remained constrained during the period of carbohydrate restriction.“
For the record, I have Anthony Colpo to thank for catching the above tidbit. The point is, any decrease in sprinting capability can be considered a crucial liability, especially since most endurance races involve sprinting at various points. Almost invariably, sprinting to some degree occurs toward the final stretch to the finish line.
The final segment of my presentation was a discussion of observational research including the carb-dominant dietary habits of the Blue Zone populations, who are among the longest-living and most disease-resistant in the world. I also discussed the carb-heavy diets of East African distance runners, who hold over 90% of the all-time world records and also the current top-10 positions in world ranking [6,7]. I concluded my lecture by relaying client case studies of high-level competitive & professional athletes, whose daily carbohydrate gram intakes ranged the high double-digits to the high triple-digits. My point was to illustrate the sprawlingly wide range of carbohydrate requirements across individuals, as opposed to the one-size-fits-all ideology of low-carb absolutists. Here’s the slide that put faces to the case studies of my athlete clientele over the years:
The Repeat Round
As I mentioned, every presentation at the conference was delivered twice, and my debate with Jeff was no exception. This made for a very odd second round, since we both knew each other’s material. The moderation was tighter on this round, and the 15-minute Powerpoint presentation limits were strictly imposed to ensure some discussion time. Jeff appeared to portray more flexibility in his position. He opted to go first again after I asked him what he preferred. He was thus able to pre-empt my mentioning of inter-individual differences in the Phinney study, and pad it with the idea that the authors expected a much worse outcome after the keto phase, but were surprised that it didn’t completely obliterate performance.
In the discussion following our presentations, Jeff once again brought up a resistance training study [2] showing the benefits of low-carb versus low-fat. Unfortunately, this study is not readily accessible, nor is it peer-reviewed. In any case, I asked Jeff if protein intake was matched between groups, and he conceded that it was not. This opens up the possibility that a significantly higher protein intake in the low-carb group could have induced greater satiety and less overall caloric intake, resulting in greater fat loss. Again, a failure to match protein (let alone match optimized intakes, which under dieting conditions would be at least double the RDA) is a frustratingly common confounder in these types of studies.
When I asked Jeff how we can reconcile the high-carb diets of the vast majority of world-class endurance champions, he proposed that these populations simply have not given low-carbing a fair enough shot. To me, this is quite a stretch since the best in the world would be foolish to jeopardize what has been working so stunningly well since the beginning of organized endurance competition. When Jeff was challenged on the concept of chronically depleted or low glycogen levels compromising the capacity for muscle growth, Jeff deflected to his current concentration on the clinical applications of carbohydrate restriction rather than hypertrophic applications per se.
Did I feel that Jeff did an excellent job presenting his side and delivering useful information? Yes, and I have a tremendous amount of respect for him and his body of work. However, judging from my own observations – as well as the feedback from others – he simply did not bring a comparatively compelling case for a low-carb/ketogenic diet’s application to competitive athletes. In contrast, I was able to present multiple lines of evidence showing the benefit of both ends of the carbohydrate intake spectrum, and many points in between.
Postscript
Overall, I enjoyed the conference immensely. I didn’t get a chance to see all of the presentations I wanted to, but the ones I was able to catch (by Brad Schoenfeld, Bret Contreras, Chad Waterbury, Lou Schuler, Marie Spano, and Mark Nutting) were top-notch. All of them delivered theoretical and practical gems of knowledge, and I can’t express enough how high the quality of education is. A large debt of gratitude is owed to Jeff Volek for agreeing to share the stage and lock horns with me. Huge thanks & kudos are due to the tireless administrators of the NSCA (special shout-outs to Peter Melanson & David Barr) for making this an event to remember.
References
Phinney SD, Bistrian BR, Evans WJ, Gervino E, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism. 1983 Aug;32(8):769-76. [PubMed]
Quann, EE. Carbohydrate restricted diets and resistance training: a powerful combination to enhance body composition and improve health. ACSM’s Certified News. Oct-Dec, 18(4), 2008.
Hu T, Mills KT, Yao L, Demanelis K, Eloustaz M, Yancy WS Jr, Kelly TN, He J, Bazzano LA. Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2012 Oct 1;176 Suppl 7:S44-54. [PubMed]
Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J Clin Nutr. 2006 May;83(5):1055-61. [PubMed]
Phinney SD. Ketogenic diets and physical performance. Nutr Metab (Lond). 2004 Aug 17;1(1):2.Phinney SD. Ketogenic diets and physical performance. Nutr Metab (Lond). 2004 Aug 17;1(1):2. [PubMed]
Beis LY, Willkomm L, Ross R, Bekele Z, Wolde B, Fudge B, Pitsiladis YP. Food and macronutrient intake of elite Ethiopian distance runners. J Int Soc Sports Nutr. 2011 May 19;8:7. doi: 10.1186/1550-2783-8-7. [PubMed]
Onywera VO, Kiplamai FK, Boit MK, Pitsiladis YP. Food and macronutrient intake of elite kenyan distance runners. Int J Sport Nutr Exerc Metab. 2004 Dec;14(6):709-19. [PubMed]
