Br J Sports Med doi:10.1136/bjsports-2014-093824
  • Editorial

Low-carbohydrate diets for athletes: what evidence?

  1. Stephen D Phinney3
  1. 1Department of Human Biology, University of Cape Town and Sports Science Institute of South Africa, Newlands, South Africa
  2. 2Department of Human Sciences, Ohio State University, Columbus, Ohio, USA
  3. 3School of Medicine (emeritus), University of California Davis, Davis, California, USA
  1. Correspondence to Professor Timothy Noakes, Department of Human Biology, University of Cape Town and Sports Science Institute of South Africa, Newlands, South Africa; timothy.noakes{at}
  • Accepted 8 May 2014
  • Published Online First 26 May 2014

Exercise scientists teach that since muscle glycogen utilisation occurs at high rates (during high-intensity exercise in carbohydrate-adapted athletes), all athletes must be advised to ingest large amounts of carbohydrate before and during exercise.1 ,2 But this does not seem entirely logical.

Why, for example, should athletes involved in prolonged submaximal exercise—probably the most common form of exercise performed by most elite and recreational athletes in training and competition—need always to eat high-carbohydrate diets in which at least 40–60% of calories are derived from carbohydrates? Surely our abundant body fat stores could provide most if not all the energy necessary to fuel activities of a submaximal intensity? Might our ability to use fat as a fuel during most activities explain the opinion that ‘a conclusive endorsement of a high-carbohydrate diet (for improved athletic performance) based on the literature is difficult to make’.3

Long-term health risks of high-carbohydrate diets

What of the long-term health consequences of habitually eating a high-carbohydrate diet especially for that increasing number of recreational athletes who may be unaware that they are insulin resistant (IR)4–6 and for whom carbohydrates pose a major health hazard including the risk of developing type 2 diabetes mellitus? The recent finding that habitual marathon runners can …

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