The answer to this question can get extremely complicated. Ketones help your body with so much (e.g. – being in “Ketosis”), and new research coming out all over the the place (see our resources section) proves that it helps with brain function, the health of your heart, and a bunch of terminal illnesses like diabetes, and cancer (yes, really!!) among other things. Here is the WikiPedia version for those of you who can understand scientific language…
Ketone bodies are three water-soluble molecules (acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone) that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate restrictive diets, starvation, prolonged intense exercise, or in untreated (or inadequately treated) type 1 diabetes mellitus. These ketone bodies are readily picked up by the extra-hepatic tissues, and converted into acetyl-CoA which then enters the citric acid cycle and is oxidized in the mitochondria for energy. In the brain, ketone bodies are also used to make acetyl-CoA into long-chain fatty acids.. – Link to WikiPedia Article
Simply put, it can be said that ketones are a byproduct of fat being burned off in your body, AND they are the preferred method of fuel your body uses instead of glucose. Ketones are metabolites with a cellular structure quite similar to glucose and they are produced in the liver out of fatty acids, in order to feed the body with energy, when glucose is low or absent (carbohydrates). Ketones can also be described as a more efficient fuel for your heart, brain and metabolism. , 
(If you are like us, and like watching a doctor explain things via video, then here is a really great one created by by Dr. Eric Berg that explains it perfectly and to the point! If you are looking for more information on Dr. Berg and his practice, it can be found by clicking here.)
If you need even more info or different perspectives of what a ketone is (sometimes some of us are not easily convinced he he) then the links below should help.
Types of Ketones
So, there are actually three types of ketones that are called “ketone bodies”.
(These were mentioned above quickly, but here is an explanation of them in short)
Both acetoacetate and beta-hydroxybutyrate are in charge of transporting energy from the liver to different tissues in the body.
How Ketones Form
During the process of ketogenesis, which is when ketone bodies are formed from the breakdown of fatty acids, acetoacetate is the first ketone that’s created.
Beta-hydroxybutyrate is then formed from acetoacetate. (It should be noted that BHB is not technically a ketone due to its chemical structure, but in the context of the ketogenic diet it’s considered to be one of the three ketones.)
Acetone, which is the simplest and least-used ketone body, is created spontaneously as a side product of acetoacetate.
If acetone is not needed for energy soon, it will break down and be removed from the body as waste through the breath or the urine. Acetone is the cause of a characteristic fruity smell on the breath when someone is in ketosis or ketoacidosis.
Why Our Bodies Use Ketones
Since the existence of humans, individuals have likely been depending on ketones for energy when glucose wasn’t generally accessible.
For example, our ancestors likely had frequent periods of time when food wasn’t immediately available — not to mention the fact that most high-calorie and more nutrient-dense foods would need to be prepared before being readily available to eat. And still today, our bodies are amazing at adapting to the burning of ketones for fuel.
Other useful advantages of ketones can include:
- A useful effect on mental performance, as a large part of the brain can use ketones as energy for mental function while on a ketogenic diet.
- Energy for exercise. Normally, the body would use the most recently eaten food or any stored glycogen as energy during a workout. So when both of those fuel systems are gone, the body adapts to the ketogenic state of creating energy from protein or fat. This can be helpful for athletes or people who do strenuous workouts and need to continue efficiently burning fat for fuel.
Testing for Ketones
Excess ketones that aren’t used by the body can spill over in a few different ways, showing up the urine, blood, and the breath. Many people who follow a ketogenic diet will do regular tests to determine their levels of ketones and ketosis, but you can also perform these tests while taking exogenous ketone supplements, in fact in those cases it’s usually recommended.
You can have a lab or your doctor test you for ketones, but there are also some ways you can do them at home, on your own, that will give you amazingly accurate and affordable results as well.
The levels of ketones present in the body can be anywhere from 0 (low) to over 3 (very high), and they are measured in millimoles per liter (mmol/L). Below are the general ranges, but keep in mind they are just guidelines, each body is different depending on your size, weight, etc etc. (Although the results may not vary that much):
Testing for Ketones, Cont’d
Urine Testing for Ketones
Method: You pee on a urine strip which tells you your level of ketones with different colors (each manufacturer has a slightly different way of displaying these results.)
Pro’s: You can buy the strips at most pharmacies for a very low cost. This is an affordable and easy option for someone new to ketosis and/or a ketogenic diet.
Con’s: Urine strips aren’t always that reliable for testing ketone levels. This is often because the longer a person is in ketosis, the more efficient the body becomes at using ketones (especially acetoacetate) for function, and so it’s possible the test can indicate a lower level of ketosis than you’re actually in. The readings can be affected by other factors, electrolytes/hydration.
Blood Testing for Ketones
Method: Using a blood glucose meter you can prick your fingertip to draw a drop of blood, then place it on a strip to verify your results.
Pro’s: This is an extremely accurate way to measure your ketone levels, this is the most effective at-home way to test yourself for ketone levels.
Con’s: This method can get expensive depending on how often you use it, some costs up to $5 – $10 per strip. Also, if you plan on testing yourself daily, your fingertips will become sore after pricking them with needles so often. NOTE: The ketone “BHB” is actually transported through the blood making this test the most effective.
Breath Testing for Ketones
Method: You use a breath meter to test the amount of Acetone on your breath, by blowing for a couple seconds into the tube (some devices may be different)
Pro’s: This is most affordable way to test your ketone levels. Many of these devices are reusable and can be carried with you when you are on the go.
Con’s: Breath meters are not the most reliable method to test your ketone levels as many factors may alter the results. Usually this device is used in conjunction with other methods (described here), and although the devices are portable, some manufacturers rely more on being a “disposable” option, so they are made cheaply.
Ketone Level Warnings
It’s important for those with diabetes to be aware of diabetic ketoacidosis (DKA), which turns the blood acidic if ketones reach a very high, dangerous level. This can happen with diabetics who are hurt, sick, or not intaking enough fluids.
It’s important to know that DKA is different from nutritional ketosis, which is safe on a healthy, nutritious ketogenic diet. For most people, there should be no concern about the formation of ketones, as they are either used or eliminated from the body and are part of a healthy weight loss and fat burning process.
Ketones can have a very beneficial role in many aspects of life, including overall health, weight loss, energy efficiency, and maintaining a wholesome ketogenic diet. Understanding the details about ketones and how they fit within the scope of ketosis and a low-carb diet is key for success in all of these areas combined!
Credits & Sources
Lab Tests Online – Testing in your Bloodhttps://labtestsonline.org/understanding/analytes/blood-ketones/tab/sample/