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A New Look at Carbohydrate-Restricted Diets: Separating Fact From Fiction

Volek, Jeff S. PhD, RD; Phinney, Stephen D. MD, PhD

doi: 10.1097/NT.0b013e31828814eb
ARTICLE: ONLINE ONLY

After 30 years of policy based on the Diet Heart (low-fat) Hypothesis, obesity and type 2 diabetes are now an epidemic. Recently published research seriously questions the dangers of dietary saturated fats and also any potential health benefits of a low-fat diet for the general population. In the context of these seismic changes in evidence-based nutrition, it is time to revisit our perspective of carbohydrate-restricted diets, not only for weight loss but also for the long-term management of conditions associated with insulin resistance. In randomized trials comparing high-carbohydrate versus low-carbohydrate diets, a well-formulated low-carbohydrate diet reduced the absolute concentration of saturated fat in serum lipids. This apparent paradox is explained by the accelerated β-oxidation of saturated fatty acids when humans are adapted to a ketogenic diet. Given that this keto-adapted state is also associated with no reduction in physical performance and reduced inflammation, carbohydrate-restricted diets may play an important role in the prevention and treatment of diseases of insulin resistance such as metabolic syndrome and type 2 diabetes.

After 30 years of policy based on the Diet Heart (low-fat) Hypothesis, obesity and type 2 diabetes are now an epidemic. Recently published research seriously questions the dangers of dietary saturated fats and also any potential health benefits of a low-fat diet for the general population. In the context of these seismic changes in evidence-based nutrition, it is time to revisit our perspective of carbohydrate-restricted diets, not only for weight loss but also for the long-term management of conditions associated with insulin resistance. In randomized trials comparing high-carbohydrate versus low-carbohydrate diets, a well-formulated low-carbohydrate diet reduced the absolute concentration of saturated fat in serum lipids. This apparent paradox is explained by the accelerated β-oxidation of saturated fatty acids when humans are adapted to a ketogenic diet. Given that this keto-adapted state is also associated with no reduction in physical performance and reduced inflammation, carbohydrate-restricted diets may play an important role in the prevention and treatment of diseases of insulin resistance such as metabolic syndrome and type 2 diabetes.

Jeff S. Volek, PhD, RD, is an associate professor and exercise and nutrition researcher in the Department of Kinesiology at the University of Connecticut, Storrs. He has publishedmore 250 than peer-reviewed studies in the last decade, including seminal work on low-carbohydrate diets.

Stephen D. Phinney, MD, PhD, is professor of medicine (emeritus) at the University of California at Davis and currently serves as a consultant in nutrition biotechnology. Dr Phinney has published more than 70 papers in the peer-reviewed literature.

Dr Volek’s work on low-carbohydrate diets has been supported by funds from the University of Connecticut Graduate School, the Health Disparity EXPORT Center at the University of Connecticut, US Department of Agriculture Hatch Funds, the Dr. Robert C. Atkins Foundation, and the Egg Nutrition Center.

Drs Volek and Phinney were coauthors on the New Atkins for a New You, released in March 2010, and the Art and Science of Low Carbohydrate Living, released in May 2011.

Drs Volek and Phinney have served on the Atkins Nutritionals Science Advisory Board.

Correspondence: Jeff S. Volek, PhD, RD, Department of Kinesiology, 2095 Hillside Rd, Unit 1110, University of Connecticut, Storrs, CT 06269-1110 (jeff.volek@uconn.edu).

© 2013 Lippincott Williams & Wilkins, Inc.