Measuring Ketones 101

One of the things that really DEFINES a “keto” or “ketogenic” diet and lifestyle is that your body is making and using ketones. That’s like, “the point” – right? =) So how do you actually KNOW if you are making and using ketones? Let’s talk about how you can measure ketones, SHOULD you measure ketones, and more. I’m going to try to keep this “middle school” science level or lower, as much as I can, so there will be some simplification to prevent losing people. =)

Wait – what ARE “ketones” anyway?

Guess we should start with what ketones are. In the context of humans (that’s you) there are 3 ketones, these are molecules and your body can use them for energy:

• BHB (Beta-hydroxybutyrate) – this is the stuff in your blood when you’re producing and using ketones.
• Acetone – yes, it’s literally the stuff used to remove nail polish – it shows up in your breath.
• Acetoacetate – I’m simplifying here, but it shows up in your urine when you’re in ketosis.

These 3 ketones have different properties but overall they indicate your body is “doing keto” and that either: you are eating in a way that lets your body make ketones from stored fats, or you took a ketone supplement. The ketones provide energy for your cells as an alternative to glucose/sugar. Again, lots of simplification here.

OK, so WHY would you measure ketones?

The best use cases for measuring ketones are:

1. You are just starting a keto lifestyle and you want to make sure you’re doing it right and your body is responding the way you want.
2. You are using a keto lifestyle to help manage a brain injury/epilepsy/some other neurological condition and having high ketones helps.
3. You are doing a test/experiment where you want to see if changing something impacts how effectively you’re making ketones.

With that first one, it can be a huge motivator to see that the changes you’ve made are producing an effect. There’s a bit of controversy in the keto space regarding inexpensive keto urine tests and how effective they are. My personal opinion (which I think is right! =) is that they can be exactly what someone needs when they are just starting off and can benefit from a simple tool that shows them “hey, you’re doing great, keep at it!”

With the second and third ones, doing tests/experiments on yourself is an excellent way to figure out what works for YOU. Spoiler alert: different people react differently to exercise, to fasting, to low carb treats, etc… While online recommendations on forums and groups CAN help guide you; it’s not going to tell you what is going to help you with SUCCESS; or what might cause you to stumble on your journey and stall your progress for months. Having something you can look at to diagnose your body’s reactions can be extremely helpful if you use it well. That said, getting too fixated on “number go up!!!” can be problematic.

How do you measure ketones?

Remember the 3 ketones above? Each one is measured differently.

Acetone gets measured with what really amounts to a fancy breathalyzer, or an extremely cheap one. I haven’t seen one like this in years, but in the 2010’s there were some very inexpensive breathalyzers that weren’t made to ignore acetone and would totally say that you are drunk if you had acetone on your breath and zero alcohol. The cool thing about measuring breath acetone is that it’s measuring the after effects of your body burning BHB ketones, as well as fat, for fuel. Because it’s a thing you blow into, you’re not having to put a paper test strip in a cup of urine, and you’re not needing to put a drop of blood on a test strip either. You can test as many times a day as you want for $0 additional cost. The PROBLEM with measuring breath acetone is that it’s technically challenging to measure breath acetone correctly. You have to exhale *just right* and measure the leftover air at the bottom of your lungs. You also can’t have any mint or alcohol on your breath, as it’ll physically burn out the sensor. Proper and accurate breath measurement also requires calibration with special gas canisters. A lot of companies and devices designed to measure breath acetone have come and gone over the last few years – some worked pretty well, others didn’t.

Acetoacetate is the cheapest to measure – dip a tester in a cup of urine and measure the result. The result of the test being un-used ketones your body didn’t need, and that’s one of the reasons some people don’t like testing urine for ketones. If you’ve been doing a keto diet for a while (like 6 months or a year), you may run into a situation where your body has gotten far more efficient at using the ketones you make… or rather only making the ketones you need. If you don’t have excess ketones, they won’t show up in a urine test like they did when you first started. This is why many people think that the urine tests are useless, but I’d like to counter again that the urine tests do an amazing job at the beginning to give you the indication and motivation that you’re on the right path.

BHB is in your blood. It’s the most “difficult” (not really difficult but compared to pee, whatever) and the most expensive of the three to measure. Before about 2017 or 2018, the way to measure BHB was using very expensive ketone test strips (seriously, it was $8 a pop!) with a special blood meter, then Keto Mojo shocked everyone with their $1 per test meter. It was nuts! =) The Keto Mojo meter and strips are still what I personally use to check my blood ketones and glucose – you’ll even find it on the “Our Favorite Things” page.

Cool (but probably not necessary) wearable tech

What if there was a wearable meter that would continuously monitor BHB blood ketones? Turns out there is one… not available in the United States (boo!). The SiBio Continuous Ketone Monitor CKM (it’s like a Continuous Glucose Monitor “CGM” but for ketones) is currently not available for purchase in the U. S. (yet – they’re working on approval) though it is available in other places. I had the opportunity to test the newer KS3 meter, which SiBio sent me for free (from Germany), though they have no control over what I post about it. It was interesting, but probably isn’t necessary for most people that aren’t biohacking or doing tests and experiments.

The Good: The sensor(s) did work – they measured blood ketones and fairly accurately when compared to blood tests using my Keto Mojo. Having a reading every 5 minutes gave me a lot of data to look at TRENDS in my blood ketones, even if the actual specific number was only fairly accurate.

The Bad: “fairly accurate” measurements isn’t really what I wanted. While there’s always going to be variation in results from ketones in my arm and in my finger, often the CKM was showing 0.2 compared to 1.2 or 1.5 on my blood tests.

The Ugly: I had a lot of connectivity problems with sensor(s), as well as problems with the software/app, and the first one I used gave me a really awful skin reaction with the adhesive – like a thick scab on my tricep for 2 weeks (though a second sensor caused zero problems with my skin and I will frequently have a rash from bandages, lucky me).

I think the software/app and connectivity issues are a result of their team actively working to fix problems. It’s not GREAT, but it’s understandable. I wasn’t happy that my first sensor disconnected and failed in the first few days, resulting in needing to get a replacement. Miriam had the same issue, though hers lasted a few days longer. On my second sensor, it lasted (I think) 11 days before an app update caused the sensor to lose the ability to keep/record readings. This loss of history was super sad for me, as I was using the CKM on a cruise (weird right?) and getting some really impressive blood ketone levels (it’s not a contest!) that aren’t saved anywhere.

The data that I was able to keep shows a very interesting story: there was a pronounced correlation between my blood glucose numbers (measured with an over-the-counter Stelo Continuous Glucose Monitor) and the CKM I was wearing. On an aside: if you want to be really “cool” with your biohacker friends, be sure to show them you have a CGM and a CKM on your tricep at the same time. So cool! =) Whenever my blood sugar (on the CGM) went below 100, the CKM was typically showing 0.5 or above. If my CGM showed below 80, the CKM was above 1.0. The price of the CKM is roughly twice what a non-prescription CGM works out to be. This leads me to the conclusion that I can likely get what I need with a CGM.

SHOULD you measure ketones?

Well now, we get to the critical question. The short answer is: no, probably not*

My personal opinion is that most people who are just consistently eating a well-formulated ketogenic diet are not going to benefit from measuring ketone levels. The old saying is “Keep Calm, and Keto On.” There is some benefit and value to be found from measuring ketones, especially if you are running into problems, if you are stalled in your progress, etc… Measuring ketones (or measuring blood sugar if you aren’t diabetic) can absolutely be a valuable tool for figuring out what you may need to change for better success; or it can be used to check if something is likely to cause you to have problems. I’ve used this to test “sugar free” items, and everybody loves Serious Keto’s video series where he tests “low carb” tortillas to see what they actually do to blood sugar levels. BUT! If you aren’t having issues or doing tests, or aren’t treating a neurological condition that benefits from high levels of ketones, measuring ketones is likely not going to give you any actionable data.