Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes

Abstract

Ketosis, the metabolic response to energy crisis, is a mechanism to sustain life by altering oxidative fuel selection. Often overlooked for its metabolic potential, ketosis is poorly understood outside of starvation or diabetic crisis. Thus, we studied the biochemical advantages of ketosis in humans using a ketone ester-based form of nutrition without the unwanted milieu of endogenous ketone body production by caloric or carbohydrate restriction. In five separate studies of 39 high-performance athletes, we show how this unique metabolic state improves physical endurance by altering fuel competition for oxidative respiration. Ketosis decreased muscle glycolysis and plasma lactate concentrations, while providing an alternative substrate for oxidative phosphorylation. Ketosis increased intramuscular triacylglycerol oxidation during exercise, even in the presence of normal muscle glycogen, co-ingested carbohydrate and elevated insulin. These findings may hold clues to greater human potential and a better understanding of fuel metabolism in health and disease.

Insulin, glucose and beta-hydroxybutyrate responses to a medium-chain triglyceride-based sports supplement: A pilot study

“…This is thought to be the reason why exogenous ketones (given as a ketone ester) have a greater performanceboosting effect when given with a source of glucose (Clarke K 2016, personal communication, October 13). 13 As fat-adapted athletes do not appear to spare glycogen during exercise despite the majority of TEE coming from fatty acids, and exogenous ketone sources have a greater benefit when given with a source of carbohydrate, glucose availability in the muscle (either from glycogen stores or from an exogenous source) still has the potential to be a ratelimiting factor to performance in the low-carb athlete. One other product, a hydrothermally processed corn starch (UCAN superstarch), has been specifically marketed to athletes eating a low-carbohydrate diet for this reason.…”

“…11,12 Exogenous ketone supplementation has also been shown to increase endurance cycling performance. 13 Supplementing with MCTs results in dose-dependent increases in circulating ketone levels (usually measured as beta-hydroxybutyrate, or BHB), but may cause gastrointestinal (GI) distress in larger doses. 3 There is a current trend in endurance sports to move athletes towards a low-carbohydrate diet or use periods of low carbohydrate consumption to increase both health and performance.…”

Ketones and inborn errors of metabolism: old friends revisited

“…A paper by Cox and colleagues in Cell Metabolism (Cox et al 2016) highlights the benefit of ketone bodies in healthy subjects. Well-trained athletes were supplemented with a synthesized ketone ester ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate ketone).…”

Wellness Fasting and Hyperketosis

“…Athletes took 15.6 g of ketone supplement and exercised. Cox et al 24 reviewed five separate studies involving a total of 39 high-performance athletes. Ketosis increased the intramuscular oxidation of triacylglycerol during exercise, even in the presence of normal muscle glycogen and elevated insulin.…”

“…[22][23][24] It contains a diester of βHB and acetoacetic acid, βHB monoester, and βHB salt with Na + , K + or Ca 2+ ions. This is a potential cause of gastrointestinal dysfunction and diarrhea.…”