Not too often does a new category of supplements come along, which are completely outside the realm of what’s traditionally been used. The keto diet popularity has become popular again, and with this old school diet comes a new wave of supplements – ketone supplements. Ketone supplementation can help induce a state of ketosis, using specific ketones, without a severe diet or fasting, while possibly enabling better performance and even an increase in fat burning.
What are Ketones?
Ketones or Ketone Bodies (KB) are used as a fuel source during exercise and become elevated during the post-workout recovery period. The use of ketone bodies is greatly influenced by what you eat, exercise intensity and your level of training. KBs include Acetoacetate (AcAc), acetone and beta-hydroxybutyrate (BHB) which are produced in the liver during conditions of reduced carbohydrate availability and can serve as an alternative fuel source for muscle, but also for tissues of the brain and heart. KBs can act as signaling metabolites, with BHB acting as an inhibitor of histone deacetylases – an important regulator of the adaptive response to exercise in skeletal muscle.
When Does the Body Use Ketone Bodies?
Ketone bodies are typically used due to a limited availability of carbohydrates in the diet as a result of a fall in both glucose and insulin. This causes an increase in the release of free fatty acids, stimulating lipolysis for use as fuel instead. Ketone bodies arise from fat-derived compounds that are produced in the mitochondria – the powerhouse energy generating cells, serving as an alternative fuel source for the body including the muscle. Ketone bodies cross the mitochondrial membranes by transporters and are converted back to acetyl-CoA that can then be used as an alternative source of energy in the The Citric Acid Cycle (TCA) – a major metabolic pathway that produces the body’s main source of energy – ATP.
Diets high in fat and low in carbohydrates can usually induce ketosis within as little as 2 to 4 days depending on the amount of available glucose stored in your muscles, the amount of carb in the diet and the type and amount of workouts performed. Traditional ketogenic diets are high in fat (80% of daily energy intake), low in carbohydrates (20 to 50 g or 5% of daily energy intake), and moderate to low in protein intake (15% of daily energy intake). In addition to diet strategies to increase ketone production, exercise can also have an impact; when glycogen levels begin to fall, ketones start to increase.
Ketone Metabolism and Exercise
Exercise performed in a fasted state can stimulate ketogenesis during exercise and results in post-exercise hyperketonemia – elevation of ketone bodies. As muscle glycogen levels fall during exercise, muscle oxidation of fatty acids increases. The extent of ketone body elevation is strongly dependent on exercise intensity, type of exercise athletic ability and nutritional status.
Trained individuals demonstrate an attenuated rise in plasma ketone body concentrations during and after exercise when compared to untrained individuals, resulting in a post-exercise increase in free fatty acid (FFA) concentrations and or increased activity of the enzymes involved in ketone body utilization. KBs have a glucose sparing action and have the potential to lower the exercise-induced rise in plasma lactate levels. They may also have a protein sparing action, which means they can help maintain muscle.
Achieving Ketosis without Dieting
Ketosis and the use of ketone bodies instead of glycogen, has been achieved via nutritional manipulation – or strict ketogenic diets. These diets may reduce the capacity to utilize carbs thereby compromising exercise training intensity and limiting exercise performance, particularly during moderate to high intensity exercise activities, such as marathon running and sprints.
Additionally, these ultra low carb diets can also lead to elevated protein oxidation or muscle loss if followed for long periods of time. Side effects of ketogenic diets can include severe cravings, fatigue and decreases in performance. Recently, the alternative to using a ketogenic diet is using ketone supplements. Ketone supplementation can result in both a fuel source and contribute to protein sparing and recovery during training.
Ketone Supplementation
Ketone supplements can be made from either ketone salts or esters. After consumption, the ester is removed from the ketone in the gut and then absorbed into circulation, where they undergo first pass metabolism in the liver to form KBs. Ingestion of ketone supplements can rapidly increase plasma KB concentrations within 1 to 2 hours. Ketone supplementation might therefore be an effective way to put the body into exogenous ketosis.
A recent preliminary study, showed that ingestion of a ketone ester beverage resulted in plasma BHB concentrations of ~5.3 mmol/L, increased glucose disposal by ~33 % and muscle glycogen content by ~50 % versus a control beverage after exhaustive exercise. Research is warranted to determine whether the possible benefits of ketone-mediated carbohydrate sparing outweigh the potential adverse effects on the maintenance of high intensity exercise performance.
Effects on Performance
In one study performed on trained cyclists, subjects performing low intensity exercise (45 to 50% of VO2 max) for 30 minutes and 2 hours, with infusions of AcAc or BHB, metabolic clearance of ketones increased 5 to 8 fold above resting conditions. Furthermore, CO2 derived from oxidation of ketones was consistently between 10.1% and 17.6% total CO2, suggesting significant oxidation of ketones in overnight fasted subjects, even at low workloads. This study showed a conservation of glucose stores during exercise, in addition to altering mitochondrial fuel selection and energetics, both determinants of physical performance.
What Do these Results Mean?
Ketone supplementation, maybe an effective means to spare glycogen, reduce protein catabolism, while also accelerating fat utilization as fuel. However, one thing that should be mentioned is that the effectiveness of ketone supplementation can be influenced by your current diet, as well as an individual’s level of fitness. When ketone supplements were taken after consumption of a mixed meal, as compared to consumption under a fasted state, ketone ester up-take was reduced as noticed by reductions in BHB concentrations.
Additionally, it has been shown that highly trained athletes utilize and uptake ketone bodies much more effectively versus those that are not trained. Ketone supplements are not currently widely available on the market yet, but some preliminary supplements have shown positive results, when combined with MCTs. When paired with MCT, the ketone body BHB, was shown to increase blood ketone levels and sustain them longer in the blood.
Until Next Time…
Be Fierce & Rule the World!
Lauren Jacobsen
References:
Cox PJ, Clarke K. Acute nutritional ketosis: implications for exercise performance and metabolism. Extrem Physiol Med. 2014. 3: 17.
Fery F, Balasse EO. Ketone body turnover during and after exercise in overnight-fasted and starved humans. Am J Physiol. 1983. 245(4):E318–E325.
Fery F, Balasse EO. Effect of exercise on the disposal of infused ketone bodies in humans. J Clin Endocrinol Metab. 1988;67(2):245–250. doi: 10.1210/jcem-67-2-245.
Holdsworth D, Cox PJ, Clarke K. Oral ketone body supplementation accelerates and enhances glycogen synthesis in human skeletal muscle following exhaustive exercise. Proc Physiol Soc. 2016. 35.
Pinckaers PJM, Churchward-Venne TA, Bailey D, Van Loon LJC. Ketone bodies and exercise performance: the next magic bullet or merely hype? Sports Med. 2017. 47: 383-91.
