Awareness and appreciation of the “low-carb high-fat” ketogenic diet has been steadily growing over the last few years. Along with that, you hear the words ketosis and ketones used more commonly. That’s excellent, but many people don’t really know what it all actually means.
..What are ketones? And what does your body do with them? What are the proper levels of ketones you should have to be in ketosis?
With so many people talking about the diet/lifestyle, it’s understandable that there is more misinformation as a result. So, let’s clear it all up in this post. First we’ll review the details of ketones – what they are, how they’re formed, etc. – and then we’ll talk about how to monitor them.
Let’s dive in!
- What Are Ketones?
- The 3 Types of Ketones
- What Is The Normal Level For Blood Ketones?
- 3 Ways To Measure Ketones
- Frequently Asked Questions
First Off, What Exactly Are Ketones?
Ketones, or ketone bodies, are byproducts created by the body in the process of breaking down (metabolizing) fat for energy, when carbohydrate levels in the body are low.
It works like this…
The body prefers to use glucose (from carbs) as its source of fuel. But when there isn’t a sufficient level of glucose, and glycogen levels are depleted, blood sugar and insulin levels are reduced, as the body looks for an alternative source of fuel: fat.
This process can occur during fasting, starvation, extended periods of exercise, or in the case we’re referring to in this post and on this site: while adhering to a low-carb, high-fat, ketogenic diet.
…When the body switches to metabolizing fats for energy – a process called beta-oxidation – instead of glucose, ketones are created as a fuel source for the body and the brain.
It is this process which is referred to as ketosis or ketogenesis…Or, as some people like to say, switching from being a “sugar burner” to a “fat burner”. If you’re eating a ketogenic diet, you’re reducing your carbohydrate intake for this reason; to get your body to change over from using glucose to using fat as its fuel source.
Other than the obvious benefit of burning fat and losing weight when the body is in this state of ketosis, there are other possible benefits, including lowered blood pressure, reduced cravings of carbs & sugars, improved cholesterol stats, deeper sleep, and more energy.
The 3 Types of Ketones:
To get a little technical for a minute, there are three types of ketone bodies:
- Acetoacetate (AcAc) is created first.
- β-hydroxybutyrate (BHB), or Beta-hydroxybutyrate, is created from acetoacetate…not technically a ketone, but considered one within the ketogenic diet.
- Acetone is a spontaneously created side product of acetoacetate, breaks down quickly, and is expelled from the body through the breath.
This is a great infographic from Perfect Keto showing the 3 types of ketone bodies
What Is The Optimal Level Of Ketones For Ketosis?
Ketone levels are measured in millimoles per liter (mmol/L), and can range from zero (in carb/sugar-burning mode) to very high (resulting in an uncontrolled state of ketosis called ketoacidosis).
Levels vary from person to person, but here are some general ketone levels:
- Negative – less than 0.6 mmol/L
- Low to Moderate – 0.6 to 1.5 mmol/L
- High – 1.6 to 3.0 mmol/L
- Extremely High – above 3.0 mmol/L
As you can see in the chart above, taken from Jeff Volek & Stephen Phinney’s book, The Art and Science of Low Carbohydrate Performance, the normal range of blood ketones for a person in ketosis is 1.0 – 3.0 mmol/L.
3 Ways To Measure Ketones:
There are a few ways to measure ketone levels, and each has its advantages & disadvantages:
- Blood – Beta-hydroxybutyrate is the ketone body that is measured in the blood, with a blood glucose meter, and this is considered the gold standard method for accurately determining ketone levels and if you’re in a state of ketosis or not.
- Breath – Using a Ketonix breath analyzer to measure acetone levels in your breath is the easiest & most convenient way to determine if you’re in or out of ketosis, BUT it’s not as reliable or accurate as blood glucose testing.
- Urine – Not as convenient as the breath analyzer, but a bit less inconvenient than a prick of the finger with a blood test. Gives a good idea of ketone levels in the beginning of a ketogenic diet, but over time not as reliable as blood testing, as blood ketone levels drop after an extended amount of time in ketosis.
Let’s cover each of these 3 in more depth…
1. Measuring Ketone Levels In Your Urine
Measuring your ketone levels in your urine is one of the easiest ways to get started, where you pee on a urine strip that indicates your ketone levels by the color it turns. When browsing Amazon, make sure to get strips that made to test ketone levels.
Pros: The strips are inexpensive and affordable, and can be bought on Amazon or at your local pharmacy.
Cons: For many people, this method loses its accuracy once a person becomes fat adapted (in a state of ketosis), as the body becomes more efficient at using ketones, thus less makes it into the urine. So you could be well into a state of ketosis, but not know it from the urine strips.
One popular brand, that is very affordable, is the Care Check Ketone Test Strips (250), as you see in the picture above.
How to measure your urine ketone levels, with most tests:
- Get a sample of your urine in a clean container.
- Place the strip in the sample (you can also pass the strip through the urine stream).
- Gently shake excess urine off the strip.
- Wait for the strip pad to change color. …
- Compare the strip pad to the color chart on the strip bottle.
2. Measuring Ketone Levels In Your Breath
Measuring breath ketones (acetone) is catching on as a popular method for analyzing and tracking ketone levels, because its the easiest way to do it. Research shows that there is good correlation between breath acetone levels and blood ketone levels.
Measure your breath ketone levels with this Ketonix Breath Analyzer
Pros: Quite simply, the main advantage is the ease of use and testing, compared to pricking your finger or peeing on a strip. After buying it, you have no ongoing future expenses of strips as you do with blood or urine testing. Also, the Ketonix analyzer comes with software that can track your ketone levels over time. If you like tech & gadgets, this is pretty cool to use.
Cons: While it can give you a good idea how much acetone you’re producing and subsequently whether you’re in ketosis, it is the least precise/accurate of the ways to monitor ketones…so if you want precise accuracy, this is not the choice for you. Additionally, at roughly $300, it is not cheap…but also don’t compare to just one package of blood glucose meter strips or urine ketone strips, rather think about the ongoing cost of buying those…the Ketonix may still be more expensive, but not terribly out of line.
How to measure breath ketone levels with Ketonix:
- Connect the device to your computer’s USB port
- Wait for the LED light to turn blue, indicating it has calibrated
- Blow gently into the mouthpiece for 10 to 20 seconds
- Read the color after 30 seconds
- Blue indicates 0-150 nmol/L
- Green indicates 150-400 nmol/L (small traces of ketones)
- Yellow indicates a possible state of ketosis at 400-930 nmol/L (moderate traces of ketones)
- Red indicates a probable state of ketosis at greater than 930 nmol/L
My Video Review Of The Ketonix Breath Ketone Analyzer
I made this video back when I first bought the Ketonix and began using it:
The price increased since I bought mine, but hearing from customer reviews, it appears they’ve also improved the newest 2017 Ketonix model.
3. Measuring Ketone Levels In Your Blood
You can test the ketone levels in your blood with a blood glucose meter, which requires you to press a lancet into your fingertip to draw a small amount of blood, and place a drop onto the test strip attached to the glucose meter.
Pros: This is the most accurate method, and gives the truest idea whether you’re in ketosis or not. Also, the meter itself is just a one-time affordable purchase.
Cons: While not a terrible experience, it is the most inconvenient way to measure…especially if you don’t like the lancet and blood getting process! Although it’s not too expensive, there is also the ongoing future cost of additional test strips.
Precision Xtra is one of the most popular brands, which you can find here on Amazon.
Ketone Levels Health Disclaimer
If you have diabetes, it’s important you’re aware of diabetic ketoacidosis (DKA), a dangerous situation resulting from a uncontrolled high level of ketones. This can occur as a result of injury, illness, or insufficient intake of fluids.
Know that diabetic ketoacidosis is not the same as nutritional ketosis (achieved on the ketogenic diet), which is completely safe. For the majority of people, the normal formation of ketones is of no concern, as the body metabolizes them and eliminates excess ketones from the body, and the process can be utilized for healthy fat burning and weight loss, along with improved overall health and energy.
If you are diabetic, or have other health issues, consult with your medical physician before starting on the ketogenic diet.
Understanding the details of ketosis we’ve just discussed, how ketones are made and utilized by your body, and how to measure them, are the keys to your success on a ketogenic diet.
Frequently Asked Questions
Q: Why do our bodies use ketones?
A: Before modern agriculture allowed for a constant supply of food, humans were more likely to frequently go without food – and our bodies are adapted for that. By being able to readily burn glucose for energy when it’s available, and then switch to burning fat reserves in times of fasting or starvation, our bodies are amazingly capable of keeping us going at all times.
Q: Do I have to purchase one these devices or strips to test ketone levels?
A: If you want to be precise and accurate, then you will need to use one of the testing methods; the blood glucose meter being the most precise. BUT, after being on the ketogenic diet for a while, you will develop a sense for whether you’re in ketosis or not by being in tune with your body and the way you feel. This is subjective, but you know your body best. In ketosis, you’ll feel more energy, have less hunger and cravings, think less about food. When you kick back into sugar-burning mode, you’ll feel lethargic, fatigued, have a foggy mind, and have cravings for junk food.
Q: How many grams of carbs can I eat and stay in ketosis?
A: This, of course, varies for each person. You will only know what your personal carbohydrate/ketosis threshold is by tracking your intake and testing your ketone levels, and adjusting as you go. But, in general, when first transitioning into the ketogenic diet, limit your carb intake to less than 30 grams. Over time, as you remain in a state of ketosis, your body’s threshold of carbs it can tolerate and stay in ketosis, can increase…you will only know through tracking and testing.
Remember to measure NET carb intake, which is total carbohydrates minus the grams of fiber.
Q: Do I need to stay in ketosis ALL of the time?
A: No. In fact, after initial weight loss has occurred, or goals hit, it’s quite beneficial to cycle in and out of ketosis. Depending on your metabolism and quickly/slowly your body gets back into ketosis, you can have “carb days” out of ketosis for 1 or 2 days, once every week or couple of weeks. A great book that teaches this method is The Carb Nite Solution by John Kiefer.