Ketonix Review


Ketonix Review

I picked up the Ketonix Acetone Breathalyzer a little over a month ago and have been playing with it ever since.  I wanted to know how accurate it was in detecting ketosis compared to the current gold standard, which are blood levels of beta-hydroxybutyrate (BHBA). I purchased this device directly from the source at based out of Sweden. The system I use to test my blood levels of BHOB is the Precision Xtra Blood Glucose and Ketone Meter (if you want to find out where to pick up strips for this you can check out this post). The way the ketonix works is very simple.  You just have to blow into the mouth piece.  That’s it!  Then the machine displays a certain colored LED light which corresponds to a certain breath acetone range.

The device itself is about the size of a large marker.  The USB cord is attached at the base.  The cord itself is about 3 feet in length, giving plenty of slack when testing.  The mouthpiece is detachable which makes it easy to wash, especially since the portion containing the electronics is not supposed to come into contact with water.  It’s important to know that when reattaching the mouthpiece, there are tiny round cutouts in the plastic that need to be lined up in order to release the air the you blow into it.  If these aren’t lined up, the air will have no where to go, and it will feel like you’re blowing into a closed system.  I’m a little embarrassed to say that it took me a few tries of blowing into it with the air not moving anywhere to figure this out…

Here are the official instructions on the label affixed to the device:

  1. Connect to USB port
  2. Wait until LED turns blue
  3. Blow gently into mouthpiece for 10-20 seconds
  4. Read color after 30 seconds

This is what each different colored LED represents:

  • Blue = 0 – 150 nmol/L
  • Green = 150 – 400 nmol/L (Small)
  • Yellow = 400 – 930 nmol/L (Moderate)
  • Red = > 930 nmol/L (Large)

Before diving into my results I wanted to briefly review the biochemistry of it all:

  • When entering ketosis, we are encouraging the body to utilize fat as fuel rather than carbohydrate (glycogen and glucose)
  • Fat is broken down into three main ketone bodies which the body then uses for energy
    • Beta-hydroxybutyrate (BHBA) – This is what is detected with blood ketone strips
    • Acetoacetate – This is what is detected with the urine ketone strips
    • Acetone – A break down product of acetoacetate which the body gets rid of via exhalation.  Acetone is what the ketonix is detecting and quantifying.


    Ketonix 2

Over the past month I’ve collected 29 separate data points where I measured both my breath acetone and my blood BHBA at the same time.  The table to the left is the summary of what I’ve found arranged in order of ascending BHBA levels.  I’ve also included my blood glucose levels for reference.

My results are nowhere near as neat as this guy’s.  In fact I was surprised to see it register as ‘moderate’ with a blood ketone level of 0.1 mmol/L and ‘high’ with levels as low as 0.2 mmol/L.  There definitely isn’t a linear correlation between breath acetone and blood BHBA… at least in my case.

So Why Isn’t The Correlation Linear?

Here are a few thoughts I had:

  • Variation based on length and quality of breath – I’ve found that the value reflected by the ketonix can be dependent on both the strength of my exhalation as well as the length of my exhalation.  The longer or harder I blow, the higher I can get it to read.

I can see this as causing some issues with reproducibility, especially if I can get different values in the span of 1-2 minutes if I accidentally blow too long (such as 20 seconds instead of the normal 10-15 seconds)… or if I blow too rigorously (much harder to standardize the strength of the breath).

At times I can get it to change between moderate to high based on varying these two factors.  This may account for why my readings are all over the place.
  • Context of testing –  I think the context of when the test is done matters greatly.  Factors such as when the most recent meal was eaten, what the macro nutrient profile of that meal was, when the most recent exercise was, what sort of exercise, etc. probably play a great deal in all this.  I haven’t provided the context in my numbers, but I will in a few subsequent posts.  
    • Exercise – I’ve read in a few places that exercise can induce metabolism of BHOB without concomitant metabolism of acetone… and this can cause BHOB to lower while acetone remains high (here and here).  
    • Food – I also wonder how things like MCT oil affects the production of BHBA vs acetone (here, here, and here).
  • Differences in ketone metabolism – There may be a lag between changes in blood BHOB appear in the breath acetone.  I think there’s already data out there describing this.  It’s generally well accepted that blood BHOB levels do not correlate with urine dipsticks which test acetoacetate (here, here, here, here, and here).  Guess where acetone comes from?  Acetoacetate.
    • Insulin – I wonder how insulin affects acetone and BHOB differently.  Sometimes I can eat a carb heavy meal and my BHOB will drop immediately… but my acetone will remain elevated.
    • Length of ketoadaptation – I wonder if the fact that I’ve been ketoadapted for so long (over a year) has altered my metabolic efficiency regarding use of BHBA vs acetone as mentioned in some of the articles that I’ve linked to above.  Perhaps if I was new to ketosis, the numbers would correlate more?


At this point, I don’t think the ketonix can replace my Precision Xtra Blood Ketone Meter readings since the correlation is so random.  The only pattern I could discern was that I consistently registered as ‘high’ for blood ketone measurements 0.9 mmol/L and above.

After writing this I also discovered how little I know regarding ketone metabolism and how much more there is to read.  So I’ll be spending the next couple of weeks trying to learn more about how ketones (BHBA vs acetone vs acetoacetate) are metabolized and how they are affected differently by diet, exercise and what not.

Response from

Of course I brought up these findings with Michel Lundell (, the man behind ketonix.  Here is what he wrote regarding the non-linear correlation (he abbreviates beta hydroxybutyrate as BHOB):

The correlation between the Ac and the BHOB is what most users want. Im in the process of putting up a submission page on the ketonix site for users of Ketonix to upload their measures with Ketonix and BHOB meters. I still have the task of finding factors that could affect the readings before announcing the “study”. The ketone levels depends on many factors. Me and other users found the length of ketosis is one major factor. Switching between low carb and high carb and the length of being in ketosis before the switch is interesting situations which I really want to be able to explain. It is a complex process with many factors involved. For the majority of users these situations is rare, one eats low carb and moderate protein and the pattern is: readings in the mornings are lower than in the afternoons. Yes, I have had some serious thoughts of sending my BHOB meters into space a few times when I have seen low BHOB readings and high Ac in breath and also a constant high readings using diastix. The Ac does not come from the BHOB, it comes from the AcAc. Studies found that the BHOB is behaving like a buffer, which makes sense when one analyze the different situations when the readings are not “as expected”. Personally I found that I need to cut proteins more than what normally is recommended, but that is probably some kind of complex relationship of exercise, body composition, keto-adaptation-phase and of course food intake 😉 . My BHOB and breath ketones are much lower when having colds. Also the BHOB’s are used when exercising, converted into AcAc and oxidised into energy. This would lower the BHOB and raising the Ac from the AcAc oxidation. Being in ketosis and doing a “pizza and beer/coke” test will trigger processes of breaking down complex carbs in your intestines that generates methane-gas which could affect the readings. Unless one does not know that one eat a pizza (that is a serious problem) the readings after such event is could be harder to interpret.

This is his response to my observation that differences in breath strength and length can affect the ketonix reading:

The way one blows into the ketonix is of course a factor that could be manipulated a lot if one really wants different results 🙂
If taking a deep breath before blowing and not blowing all air out of the lungs … most air will be “clean”. It takes a small amount of time for acetone to mix with air. Air temperature also is a parameter, so If you blow into the device for a longer time, the device and gas will produce a higher value.
What you want is the most concentration of acetone in your breath, to get consistent readings , I recommend is to follow the same procedure each time.

1) Plug in the Ketonix to a USB port to power it up. 2) Wait until the blue light is steady. 3) Take a “normal” breath (hard when you think of just doing it, but avoid a deep breath) 4) Exhale into the mouthpiece until all air is out 5) Read the value.

He also tells me that he’s noticed that insulin affects BHBA and acetone differently.


Now here’s the cool part.  He wanted me to mention that he is in the process of releasing an upgraded version of the device with better calibration and more consistent readings.  If you already have the device, you would just need to pay $10 to ship yours back to him and he will send you the new version.
He will also be releasing two different versions.  A “standard” one, similar to the one that I just reviewed and “sport” version that will be able to measure higher levels of breath acetone.


I feel very confident that this device will tell me qualitatively whether or not I’m in ketosis.  It’s the quantitative measurement that’s the issue, since it doesn’t correlate well with the current gold standard of blood ketones.  The other issue is that because of a possible lag, the device may tell me that I’m in ketosis, while my blood ketones tell me that I’m not… and this is where the main problem is currently.
While I can’t quite throw out all of my blood ketone strips, I’m not quite ready to give up on the ketonix either.  I’m looking forward to getting the upgraded version soon so that I can continue my testing.  I’m still hopeful that this will eventually allow me to replace all those expensive ketone strips and the painful finger pricks.
Stay tuned…
Thanks for reading this far into ketonix review.  I’d love to hear any thoughts and suggestions you all have.

UPDATE 2/23/15:

I finally got around to posting my full Ketonix Sport Review here!


UPDATE 5/31/2015:

At this point in time the Ketonix is no longer available on Amazon.  

If you are interested in picking one up the 2015 Ketonix model is the only one available and it is available only on the Ketonix site for $149.

31 Responses to Ketonix Review

  1. Ash Simmonds says:

    Cool stuff.

    If only we could isolate acetone from ethanol…

  2. Ward says:

    Interesting, thanks for the review. I also have a ketonix and while the correlation of acetone with BOHB is not perfect the advantage of the ketonix seems to be that 1) I use the device frequently and can get an idea of how diet, exercise,… effects the process of ketone generation (the acetone portion of the ketone system) and 2) I’m not spending an arm and a leg testing. I like it.

    • BJJ Caveman says:

      Yup. I think this is where it will ultimately fall for me.

      A way to qualitatively test for whether or not I’m in ketosis without having to go through the inconvenience of collecting my pee… or pricking my finger (despite the accuracy of this).

      But I still wanna play around with it a little more!

  3. Jonny V says:

    Awesome review. I just ordered mine a few days ago. I am getting sick of ketostix and I definitely don’t want to prick my fingers a ton. The fact that it doesn’t need some kind of replacement or strip in between readings is just great. Bummed that I will have to ship it back soon after I get it to get the new and improved one, but I think that’s nice of the creator to do that.

    • BJJ Caveman says:

      Yup. The creator is very approachable and friendly throughout our entire correspondance, and he seems very open to our feedback!

  4. Adam says:

    Any hints on the release time and price on the updated version? I also saw on reddit that this sold for 500 SEK = ~$75, is it possible to still pay in SEK, I only see USD when I visit the site and they are asking for $100.
    I am wondering if it would be cheaper to buy this one and return it for the new one if the new one is going to be more expensive.

    • BJJ Caveman says:

      Haven’t received my new Sport Ketonix yet.

      It looks like he changed the price since he’s getting so many US orders, and the upgrade button isn’t available anymore… so I’m not sure what the status is. Will release a post once I find out more.

  5. Jafar Calley says:

    I got my Sport after a week. Blew a green (flashes 6 times). Since I’ve been keto for about 18 months, I guess that reading is ok for someone keto adapted.

  6. Damon says:

    You’ve put out some real high quality reviews. Just bought my sport version if ketonix and will be interested to see my own correlations with blood ketones. Keep up the good work.

  7. Josh says:

    Great review thanks for the link for the blood ketone monitor, I’ve be looking for one forver

  8. mark says:

    Thanks for taking the time to put together such a thorough review. I’ve had the sport for a couple of months and bought it based off of what I read here. Can’t wait to hear your thoughts on the sport!

  9. Michelst says:

    Just a comment on correlation with bhob’s

    When bhob’s is used as energy, they do that via acetoacetate. E.g the bhob concentration decrease and acetone (from acetoacetate) increase.

    Another case is if having a decent level of bhob and body is resting, there is not much need to make more energy, e.g the ketogenesis is low (generation of acetoacetate is low). During this rest (sleep) acetone is broken down in liver and exhaled. This is why readings in the morning usually are lower than in the afternoon.

    Just to point out that acetone and bhob are different animals.

    Acetone indicates generation of acetoacetate (and use of bhob).
    Bhob I concider more as a ketone energy reserve.

    Best regards

    • BJJ Caveman says:

      That’s fantastic! Thanks for chiming in Michel. I would like to read more about this, are there any papers that you can refer me to? I’d like to have a better understanding on the relationships between the three ketone bodies and how they interact.

  10. Dr. Ted Ace says:

    My blood ketone and Ketonix correlations same as yours – all over the place. Here is a great article: but Michel Lundell’s advise on how to breath properly into the device is priceless.

  11. Jen says:

    Those meters are not on Amazon, at all right now. Please update

  12. Jt says:

    I just ordered ketonix. I’ve been using ketostix and Nova Max blood ketone meter. I was hoping I could save some money by buying the ketonix instead of the blood test strips which are quite expensive. But based on your review, it looks like I may still want to use the blood ketone monitor.

  13. Paulo A.Lopes says:

    “To use the device in a low-carb context is the intended use. If using it with a diet with high carbohydrates it will indicate methane created by bacterias breaking down carbs in your gut (fart warning). In a low-carb context this is not really a problem, the carbs … are low. To minimize the influence of any methane gas from the gut, drink a large glass of cold water before testing.
    It is also sensitive to alcohol, so ”don’t drink and test”. Drinking alcohol will stop your ketosis until the alcohol is gone”

  14. Ash Simmonds says:

    Alcohol doesn’t “stop your ketosis”, it just interferes with the device sensor as it can’t distinguish ethanol from acetone, I said that on my first comment in this post over a year ago:

    Ethanol tends to *deepen* ketosis in the absence of other energy sources, hence “alcoholic ketoacidosis” is a thing.

    I’ve pulled the Ketonix apart, the actual sensor that picks up the “airborne toxins” is a $3 part from BMW, I can’t remember exactly it’s purpose now but I think it’s like something that sits within the structure of the car (like in bulkheads/doors or whatevs) and if it detects anything noxious/flammable (like acetone/ethanol/etc) then it can send a signal to the car to lock shit down, or something.

  15. JonGrant says:

    I think what people would want (and I certainly do) is a reusable system with good resolution, accuracy, and low cost per test. Resolution in the ketonix system is pitiful. Accuracy? Who knows since the lack of resolution makes accuracy meaningless. Cost per test is very low.

    What I would like to be able to do is to see what changes to SFA:MUFA:PUFA do to ketones. Or, how carb content of meals quantitatively affect ketone levels. I guess we are stuck with $4 per test strips, or Ketostix. I will stick to ketostix (I don’t think they could be shown to be less accurate than ketonix).

  16. David says:

    I just ordered one because im addicted to the keto sticks, also im sick of peeing into a cup. ive read that breath analyzers are more accurate though as youve found they dont exactly correlate with blood results. It should be unsurprising however because of the three sources of material for ketonic measurement only one of them isnt a waste product. Both urine and breath exhalation are “waste ” products.

  17. HBJ says:

    mine wont work at all and no one to get help from. Dont do it.

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