The Fourth Fuel Source

Exogenous Ketones are not Affordable by All

​The ketogenic diet is a famous diet that has been tried and tested by many people worldwide. Even if individuals don’t have personal experiences, they are sure to know someone who has tried the keto diet. But what about exogenous ketones that impact health and performance?

Ketones
Ketones are metabolites of fat oxidation or in simple terms, are produced when the body burns fat for energy or fuel. Their utmost importance lies in providing fuel to the brain as the brain can make use of only glucose and ketone bodies for energy. The brain usually relies on carbs as a substrate compared to lipids and during starvation, lipids are used to sustain brain functioning via these ketone bodies.

Nutritional Ketosis
Carbs and glucose are primary energy providers to human body. Ketosis is a metabolic state in which ketone bodies act as primary energy providers to the body in comparison to the glycolysis state in which blood glucose provides energy. The primary ketone bodies used for energy include acetoacetate and β-hydroxybutyrate.

Nutritional ketosis is the state of increased ketone levels in the body that is feasible through multiple ways such as fasting, by consuming a low-carbohydrate diet (less than 50 grams daily), exercising for a long time without carbs or by consuming exogenous ketones. We call it exogenous as we are taking a product that has been produced outside the human body. It is important to note that the terms ketosis and ketogenic have slightly different meanings. Ketosis is increased blood-ketone levels either from endogenous (produced in the liver) or exogenous (taken as supplement) ketones. Ketogenic is the existence of elevated ketone bodies as a result of following a low-carbohydrate, high-fat diet and the ketogenic diet is the best example. Read more about this diet, its advantages and side effects at www.firsteatright.com. 

Exogenous Ketones
There are two variations of exogenous ketones-salt and esters (mono- and di-esters). Ketone salts that are reasonably priced have mild impact on ketone levels raising the blood ketone levels to around 1 mmol and having a high salt load. Ketone esters, on the other hand, have a significant impact on blood ketones raising blood ketone levels to 3-4 mmol within 20 to 30 minutes of ingestion.

Impact of Exogenous Ketones
The impact of exogenous ketones on endurance performance is interesting as two important studies on this prove contrasting results-one shows positive effects and the other showed negative effects, but one has to remember that the protocols used for testing purpose varied significantly. Exogenous ketones are advantageous when there is overall improvement in substrate metabolism and prove beneficial in numerous ways:
​

1. Preserve carbs breakdown for energy during exercise thereby helping preserve endogenous fuel.
2. Ketones don’t have much impact on insulin compared to carbohydrates and amino acids and hence, are a preferential supplement for individuals with insulin resistance.
3. While fats are utilized during exercise, ketones are oxidized only at higher intensities.
4. Some researchers suggest that exogenous ketones might be helpful in improving symptoms of Alzheimer’s, brain injury, oxygen toxicity and certain cancers.
5. Brain trauma and vascular disease reduce the brain’s ability to utilize glucose. These ketones may provide a fuel source to these energy-deprived brains.
   
   

Some of the disadvantages of ketones include:

1. Palatability and tolerance is an often-debated topic of ketones as most supplementary ketones are bitter to taste and might also cause gastric upset in certain individuals.
2. Although marketed as fat-burning supplements, exogenous ketones will not provide the same body composition-improving results when compared to a ketogenic diet.
3. Ketone salts and esters have zero impact on body composition as they provide calories.
   ​

To summarize, exogenous ketones might work as the fourth fuel source but do not prove to be advantageous over other energy sources such as carbohydrates, fat and protein. These ketones neither elevate nor decrease performance (expect for the side effects that they cause gastric trouble and cost more) and individuals who can afford to spend and tolerate its side effects can consume exogenous ketones as they might help preserve endogenous fuels.