The ketogenic diet is a hot topic in the diet today. Keto recipes are everywhere and everyone knows someone who has at least tried the keto diet. But what exactly are "exogenous ketones", where do they find themselves and how do they influence health and performance?
What are ketones?
Ketones (also called ketone bodies) are metabolites of fat oxidation and are produced in the liver. The foremost circulating ketones in the blood are acetoacetate (AcAc) and 3-beta-hydroxybutyrate (3HB). Their primary function is the provision of brain fuel, as the brain can only use glucose and ketone bodies for energy. In addition, ketones can act as hormones and be oxidized into muscle during exercise.
Nutritional ketosis (ie elevated levels of ketone in the body) can be achieved in a number of ways, including fasting, following a carbohydrate-restricted diet (<50 grams / day), prolonged exercise without carbohydrate intake, or by eating exogenous ketones , Exogenously means consumption of a product produced outside the body, whereas endogenously describes the breakdown of stored fuels in the body (typically carbohydrates, fats and proteins).
Ketosis and ketogenic have slightly different meanings. Ketosis describes elevated blood ketone levels of either endogenous or exogenous ketones (i.e., produced from the liver or taken as a supplement). Ketogen describes a condition of elevated ketone bodies from a low carbohydrate, high fat diet (such as the ketogenic diet).
Forms of exogenous ketones
Exogenous ketones are available in two forms: salts and esters (both mono- and diesters). Ketone salts are commercially available, relatively affordable (~ $ 4 / serving) and tasty (taste similar to sports drinks). They have little effect on the ketones, normally increasing the ketone levels in the blood to about 1
in contrast, significant effects on the blood ketones, potential increase to 3-4 mmol within 20 to 30 minutes after ingestion. However, they are not widely available. At the time of this release, a product is commercially available and is extremely expensive at ~ 30 / serving. At this time, ketone esters are mostly only available for research purposes that are still in their infancy.
Application and research on exogenous ketones
So far, research on human subjects has investigated the effects of exogenous ketones on endurance performance. Interestingly, the two main studies have contradictory results. Cox et al. (2016) and Leckey et al. (2017) show positive or negative results. It is worth noting, however, that these two studies showed significant differences in the test protocols used by the researchers.
Proponents believe that the potential benefits of exogenous ketones result from an improvement in total substrate metabolism. Exogenous ketones can get endogenous fuel; In other words, limiting (or possibly suppressing) the removal of carbohydrates for energy during exercise. In contrast to the conventional fat utilization model, ketones are oxidized at high intensities. In addition, ketones do not affect insulin like carbohydrates and amino acids; therefore, they may be a preferred supplement for individuals with insulin resistance.
The potential disadvantages of exogenous ketones are their palatability and tolerance. Complementary ketone esters are very bitter and cause significant upset stomach in some patients.
Ketone salts and esters are unlikely to affect body composition as they still provide calories. They can be mis-marketed as fat burning preparations (which is technically correct, since ketones are derived from fat), but exogenous ketones are unlikely to give the same body composition-enhancing results as an energy-restricted or ketogenic diet.
Exogenous ketones can also be used in the medical field, with some suggesting that they have the potential to improve the symptoms of Alzheimer's, traumatic brain injury, oxygen toxicity and certain cancers. Brain trauma (either acute or chronic) and vascular disease reduce the ability of the brain to use glucose. Thus, circulating ketones can provide an energy source for a low-energy brain.
During exercise, exogenous ketones can function essentially as a fourth source of energy. Due to limited research, they do not necessarily offer an advantage over other exogenous fuels (carbohydrates, fat or protein). If you can afford it and tolerate it, exogenous ketones are unlikely to decrease performance (because so far the only side effects are high cost and gastrointestinal disorders) and may endogenous fuels.
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