CURRENT RESEARCH
We are, together and separately, involved in a number of research projects which includes an international list of scientific collaborators. The central focus of these projects is understanding the physiology and functional application of low carbohydrate nutrition. Our two major current projects involve:
1) A study of how carbohydrate tolerance varies among men and women with metabolic syndrome
2) How the acute stress of running a 100-mile foot-race affects oxidative stress and inflammation in athletes eating varying levels of dietary carbohydrate
PRIOR RESEARCH
Of our many hundreds of papers, here are a few from each of us that we think have made significant contributions to progress in our understanding of low carbohydrate nutrition.
Steve
SD Phinney, ES Horton, EAH Sims, Hanson JS. Capacity for moderate exercise in obese subjects after adaptation to a hypocaloric, ketogenic diet. Journal of Clinical Investigation 1980
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC371554/pdf/jcinvest00695-0284.pdf
Comment. Until this study was published, it was universally understood (and taught) that a ketogenic diet was necessarily debilitating. Although our measurement of the exercise capacity of our subjects was confounded by their major weight loss, it was clear that whereas they were impaired after one week of the ketogenic diet, they then experienced a remarkable resurgence in performance by the 6th week of adaptation to the diet. In this study, we also discovered the need for a modest salt intake to counter-act the accelerated sodium losses caused by nutritional ketosis.
SD Phinney, BR Bistrian, WJ Evans, E Gervino, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism, 1983
Comment: This benchmark study of highly trained cyclists fed a high fat, moderate protein, ketogenic diet for 4 weeks demonstrated that there was no loss of peak aerobic power or endurance time to exhaustion if adequate time was allowed for keto-adaptation to occur. Given that all antecedent and most subsequent studies purporting to show the superiority of a high carbohydrate diet in endurance sport lasted less than 2 weeks, our study essentially re-defined the importance of ‘carbohydrate loading’. These keto-adapted athletes also demonstrated much higher peak fat oxidation rates than was thought possible.
SD Phinney, PG Davis, SB Johnson, RT Holman. Obesity and weight loss alter serum polyunsaturated lipids in humans. Am J Clin Nutrition 1991.
http://ajcn.nutrition.org/content/53/4/831.full.pdf
Comment. The human body’s handling of polyunsaturated fats (which are vital components of every membrane in and around cells) is extremely complex. In this study, we discovered that a ketogenic diet dramatically alters the metabolism of these essential fats, but those changes are reversed when the ketogenic diet is stopped. Over 20 years later, we are still trying to understand why this happens and what it means. But in hindsight, this study was our first harbinger that nutritional ketosis reduces oxidative stress and inflammation, which makes the body’s task of maintaining optimum membrane composition much easier.
Jeff
JS Volek, AL Gómez, WJ Kraemer. Fasting and postprandial lipoprotein responses to a low-carbohydrate diet supplemented with n-3 fatty acids. Journal of the American College of Nutrition 2000.
http://www.jacn.org/content/19/3/383.full
Comment. Having read Steve’s research published 2 decades earlier; I was perplexed why such provocative work was essential ignored. This paper was my first published in the area of low carbohydrate diets and focused on blood lipoprotein responses in normal weight men with normal cholesterol levels. Prior research had shown that high levels of fat in the blood, especially after consumption of high fat meals (i.e., postprandial lipemia), significantly increased a person’s risk of heart disease. In this study we took repeated measures of blood fat (triglycerides) after subjects ingested a single high fat meal. We had them ingest the same high fat meal 6 weeks after consuming a ketogenic diet. Remarkably the serum triglyceride response to the meal was decreased by half after the ketogenic diet, demonstrating a profound improvement in metabolizing dietary fat. We subsequently replicated this hallmark postprandial reduction in blood fat response to carb restriction in separate experiments in normal-weight and overweight men and women.
JS Volek JS, MJ Sharman, AL Gómez, DA Judelson, MR Rubin, G Watson, B Sokmen, R Silvestre, DN French, WJ Kraemer. Comparison of an energy-restricted very low-carbohydrate and low-fat diet on weight loss and body composition in overweight men and women. Nutrition and Metabolism (Lond) 2004.
http://www.biomedcentral.com/content/pdf/1743-7075-1-13.pdf
Comment. These experiments involved overweight men who consumed both low carb and low fat weight loss diets to determine which one they responded most favorably to. Consistently they lost more weight and more body fat in response to the low carb diet, and they improved markers of metabolic syndrome to a greater extent. Notably, this was the first study to show that the low carb diet was associated with greater loss of abdominal fat as measured by dual-energy x-ray absorptiometry.
CE Forsythe, SD Phinney, ML Fernandez, EE Quann, RJ Wood, DM Bibus, WJ Kraemer, RD Feinman, JS Volek. Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation. Lipids 2008.
CE Forsythe, SD Phinney, RD Feinman, BM Volk, D Freidenreich, E Quann, K Ballard, MJ Puglusi, CM Maresh, WJ Kraemer, DM Bibus, ML Fernandez, JS Volek. Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet. Lipids 2010.
http://yaboga.com/lowcarbvascular.pdf
JS Volek, KD Ballard, R Silvestre, DA Judelson, EE Quann, CE Forsythe, ML Fernandez, WJ Kraemer. Effects of dietary carbohydrate restriction vs low-fat diet on flow-mediated dilation. Metabolism 2009.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974193/
Comment. Among many original findings in this study of 40 people with metabolic syndrome put on either a high carb or a low carb weight loss diet, there were two that are extremely important. One, this is the first human study to show that humans who are keto-adapted have decreased blood levels of saturated fats despite eating more of them (Forsythe 2008). A couple years later we replicated this remarkable finding in a controlled feeding study in normal-weight men fed isocaloric weight maintenance diets (Forsythe 2010). Two, this study definitively demonstrated that being keto-adapted is associated with significant, across-the-board reductions in a host of biomarkers of inflammation. In a follow up paper, we published data showing that the low carb diet improved fasting and postprandial vascular function in response to a high fat meal (Volek et al. 2009).
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