Ketonix Sport Review

BJJ Caveman Ketonix Sport Review


It’s been almost 8 months since I’ve picked up the Ketonix Sport directly from the Ketonix website, and in the interim it seems like the owner, Michel Lundell, has moved over to the Amazon platform.  Currently there are two versions available on Amazon:

When I first purchased this the additional battery wasn’t available so I can’t really comment on how the battery works.

[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.]

What’s in the package?

The package is similar to what was contained with the Ketonix Standard version.  It was shipped in a sturdy card board box and includes a blue velvet protective pouch (the Ketonix Standard came with a leather pouch).  The Ketonix Sport itself looks exactly the same as the Ketonix Standard except for the brown color of the label and the words “Ketonix Sport.”

Like the standard version, the Ketonix Sport is the size of a large marker with a 3 foot USB cord attached to the base.

How to use it

The directions on the label read:

  1. Connect to a USB port
  2. Wait until blue led is steady
  3. Blow gently into mouthpiece (10-15 sec)
  4. Watch the led color inside
  • Blue led – none/very small trace of ketones
  • Green led – small trace of ketones
  • Yellow led – moderate trace of ketones
  • Red blinking led – high trace of ketones

Wait until the blue led is steady before taking a new measurement.  Do not use after meals or drinking alcohol.  Keep out of reach for children.  Do not use in water or vehicles.

For additional instructions you can refer to the Ketonix Support and Usage pages where he offers additional tidbits like always storing the Ketonix Sport in the pouch to protect the sensor and more detailed breathing instructions.

I noticed that on some days the Ketonix Sport would take 30 secs to calibrate and on other days it would take up to 2 minutes!  I couldn’t figure out what variables affected this, but I frequently got impatient when it took 2 minutes to calibrate.

Brief Biochemistry Review

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.  Breath acetone is what the Ketonix Sport detects.

If you’d like a little more biochemistry and basics you can check out my Start Here page.

Difference between the Ketonix Sport and the Ketonix Standard

The primary difference is that the Ketonix Sport provides more detailed information for the exhaled breath ketones than the Ketonix Standard (here is my full review on the Ketonix Standard).

The Ketonix Standard displays 4 different LED colors:

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

The Ketonix Sport offers the same colors, however further breaks things down with differing amounts of flashes.  The green LED can flash anywhere from 1 time to 10 times.  The yellow and red LEDs also do the same and these flashes correspond to a more specific amount of breath ketones.

This is the graphic provided on the product page:

Ketonix Sport RangeThey seem to have changed the units from nmol/L to PPM from when I purchased the Ketonix Standard.

My interpretation of this scale is something like:

Blue ~ 0 – 5 ppm

Green ~ 5 – 10 ppm  (with range of 10 flashes)
Yellow ~ 10 – 20 ppm (with range of 10 flashes)
Red ~ 20 – 40 ppm (with range of 10 flashes)

So theoretically, a Yellow with 5 flashes would indicate around 15 ppm, and a Red with 5 flashes would indicate 30 ppm

On the other hand, in the videos Michel posts, he shows the green flashing twice and says it’s ~ 10 ppm, yellow flashing seven times being ~ 20 ppm, and red flashing three times being ~40 ppm… so I’m not entirely sure about this.

How I tested thisKetonix Sport Key

From October 27, 2014 to November 14, 2014, in the midst of my latest Carb Nite experiment (Week 1 and Week 2, unfortunately I never got around to posting the following weeks), I tested my fasting AM blood sugars and PM pre bed time blood sugars using the FreeStyle Lite Glucose Monitory System.

At the same time, I tested my blood ketones (both AM and PM) using the Precision Xtra Blood Ketone and Glucose System, and breathed into the Ketonix Sport.

If you want to see exactly what I ate during this time period, feel free to add me as a friend on myfitnesspal and browse through my food diary.

To make things a little easier to chart I assigned a linear numerical value to each potential combination of LED color and number of flashes.

As you can see on the chart to the right, I assigned a value of “0” to the blue color, and a number 1-10 for the color green, 11-20 for yellow, and 21-30 for red.

So if the Ketonix Sport showed a yellow light that flashed 4 times, this would correspond to the value ’14’ on my table.

If the Ketonix Sport showed a red light that flashed 7 times, this would correspond to ’27.’

My Hopes

I had high hopes for what the Ketonix Sport could provide in terms of data.  In the best case scenario, I wanted there to be a clear linear relationship between blood ketones and breath acetone.

If my Precision Xtra showed 0.6 mmol/L, I wanted the Ketonix Sport to always show the same color and number of flashes.

If my Precision Xtra showed 2.5 mmol/L, I wanted the Ketonix Sport to show an even higher LED and number of flashes that was reproducible.

As we saw with my Ketonix Standard review this type of linear relationship did not exist.  I hoped the Ketonix Sport would be different.


Is there a linear relationship?

Ketonix Sport Nonlinear Data

The answer is a big fat NO.  I arranged the data in ascending order of blood ketone values.  You can see that over the course of the experiment, my blood ketones ranged from 0.2 mmol/L to 1.5 mmol/L (a legitimate criticism of this is that I didn’t have higher blood ketone measurements like in the 2.0 or 3.0 mmol/L range).

For a blood ketone measurement of 0.4 mmol/L you can see that Ketonix Sport reported values of 6, 11, 21, and 22, which is a huge range.

The same could be said for all the other blood ketone measurements.

My hopes were dashed.  No linear relationship existed whatsoever.  For a given blood ketone measurement, it seemed that the Ketonix Sport would pull a random number out of a hat.  I mean how could a 0.2 mmol/L blood ketone measurement correspond to a breath acetone of either a 6 OR 16?

So, I played with the data a bit…

I wondered if I was missing something.  Maybe there was a correlation that I just wasn’t seeing.  So I organized the data chronologically and made some charts…

AM Blood Ketone vs Ketonix Sport Breath Acetone

AM Blood Ketones vs Breath Acetone

Do you see any clear relationship?  Positive correlation?  Negative correlation?  Me neither.  There might be something there… but nothing definitive.

PM Blood Ketone vs Ketonix Sport Breath Acetone

PM Blood Ketone vs Ketonix Sport Breath Acetone

Hmm… again, maybe there’s something there?  There’s a gap here where I forgot to take PM measurements one evening because I was waylaid by an inadvertent BBC Sherlock Holmes marathon.

Both AM and PM Blood Ketone vs Ketonix Sport Breath Acetone

AM and PM Blood Ketone vs Ketonix Sport Breath Acetone


Having so many data points made things look noisier on this chart.  I thought I saw a pattern here but I still wasn’t convinced.

So I started wondering about trends.  While the Ketonix Sport fails miserably in correlating with blood ketone measurements linearly, perhaps it correlated better in terms of general trends.

To further explore this, I took the same data set used here, with both AM and PM measurements, changed them to a scatter plot, and used a trend line with a 5 period simple moving average.

AM and PM Blood Ketone vs Ketonix Sport Breath Acetone 5 Period Simple Moving Average

AM and PM Blood Ketone vs Ketonix Sport 5 period simple moving averageWow.  The trend lines are almost identical!  There is a pretty clear positive correlation between the two trends.


After spending a good amount of time with the Ketonix Sport and parsing through all this data I feel like I can say for certain that it is a powerful tool if you’re interested in pursuing a ketogenic diet.

It’s not going to give you the moment by moment details that the current gold standard, blood ketones, can give you, but if you use it consistently, it will give you an accurate trend of where you’re going and where you’ve been.

It can tell you if you’re getting more ketotic or less ketotic, but it won’t give you an absolute number.

It’s important to remember that individual breath acetone measurements are essentially worthless, but the trend is where the money is.

If tracking your state of ketosis is important to you then I think this is the most cost effective tool for doing so.  Since we already know how inaccurate urine dipsticks can be the longer you are ketoadapted I can’t encourage the use of these.

I recommend using the Precision Xtra Blood Ketone and Glucose System if:

  • Having accurate measurements is important to you (blood ketones are the gold standard)
  • You don’t mind constant finger pricks
  • You can afford the $3-5 per blood ketone strip
  • You want to know how certain foods or activities affect your blood ketones on a minute by minute or hour by hour basis

The Ketonix Sport is perfect for you if:

  • You’re ok with just knowing your general state of ketosis (by taking consistent measurements to get an accurate trend)
  • You want to save money (this will pay for itself after 30-40 measurements)
  • You value convenience (just blow into this thing for 15 secs)
  • You’re ok with the variable calibration times (30 secs to 2 minutes)
  • You understand it’s limitations.

If you want to pick one up you can get it at Amazon here:


Over at the KetoGains Subreddit where I shared this post, user leclisse kindly created a scatterplot comparing blood BHOB and the Ketonix readings:

Ketonix Sport Scatterplot

Leclisse also did some statistical analysis and calculated rho = 0.316 and p = .03, which doesn’t really mean anything to me since I completely suck at statistics (anything beyond mean, median, and mode is beyond me)… so I’ll just cut and post leclisse’s entire comment:

There’s a positive correlation after statistical analysis for your data: rho = .316, p = .03 one-tailed. EDIT: just to make sure no one takes this incorrectly, this sort of analysis isn’t exactly appropriate; we can’t conclude that this correlation exists in anyone else, just that in you the readings are correlated.

Details—SPSS 21. Your data were non-normal and ketonix may not be scalar, so I used a nonparametric spearman’s correlation; one-tailed significance testing because we expect (and previous studies show) a positive correlation.

28 Responses to Ketonix Sport Review

  1. Mary Jo Kringas says:

    Thank you for this very thorough review. My Sport model has not yet arrived and I was wondering how it compares to the Precision Xtra. Best, Mary Jo

  2. Sascha Heid says:

    Awesome review. You rock!

  3. Kathy says:

    I have bought two of these several months ago. The first was for my boyfriend who was getting into the Bulletproof diet and then one for myself. His seemed to work fine, and his results have been consistent. Mine, on the other hand, was just plain wrong. After indulging in Thanksgiving feasts, my Ketonix showed yellow. Once I got back to eating low carb again for about a week, it showed yellow and red. I found this to be odd and very unlikely. Upon comparing it with my boyfriend’s, I found the results to be drastically different each time. I sent it back to get fixed at my cost of $25. I just got it back and am still getting different results between the two. I would just like a refund, but don’t know if that is an option and would have to spend another $25 to return it. I was so excited about this product but so deflated now.

    • BJJ Caveman says:

      I’m sorry to hear that you’re having such a bad experience with it. Michel the guy who makes it has been very friendly and communicative with me, so try reaching out to him and explaining the situation.

  4. Nilo says:

    That’s pretty much the results I’ve been getting. For instance, after a carb-load regimen of eating over 800g carbs per day with TONS of sugar and fructose for 3 days in a row, I would get six red flashes or similar readings hours after meals (shortly or several hours after – it didn’t matter really) and basically it would not matter a bit if I was on ketosis or not. Of course I tested using the blood method just to be sure no metabolic abnormality was happening lol, and as expected I would get a BHB reading of 0.2 mmol/l. Even when the context was different, during strict keto conditions, the results were not much better.

    Bottom line, this device is pretty much useless for getting any meaningful (short-term anyway which is the reason people buy this in the first place) readings regarding ketosis. Contrary to what many folks think, it doesn’t even reliably indicate if you are in ketosis or not. So even worthless than the old urine strips, really.

    • Will says:

      I guess I should have read this before posing my question (duh). As with most non-functional mechanisms, I guess the Ketonix unit has gone the way of the flightless dodo bird.

  5. Will says:

    Anybody know why the Ketonix unit is nowhere to be found anymore? It’s not available either on Amazon nor its OWN site? Hmmmm…

    • BJJ Caveman says:

      I spoke with Michel, and he said that he’s run into some problems with Amazon… so once that all gets sorted out, it should be back up.

  6. Shirley says:

    Hi, I am using the blue Ketonix . What is the difference between it and the red? I am getting high yellow and lo red all the time. Ism watching what I eat. Is this reliable or not. I paid 165.00 now I’m hearing it is not reading good. How can I know?

    • BJJ Caveman says:

      I don’t think there IS a difference between the blue and the red except for the default setting it comes in (either defaulted as sport or standard), but this can be changed using the software.

      In terms of how reliable it is or not, I can’t say since I haven’t really done a direct comparison with the blood ketones yet. All I can comment on is what you see in this review.

      I think the only way to know for certain is to correlate with blood ketones…

  7. Philip says:

    Re testing time or time to breath into the Ketonix, I find that I get more reliable results if I breath into the Ketonix for 45 seconds. I see that you used 10-15 seconds in your evaluations, was this time recommended by the manufacturer?. FYI I am using the 2015 model.

    • BJJ Caveman says:

      Yes 10-15 seconds was recommended by the manufacturer for the Standard Ketonix and Ketonix Sport versions that I reviewed. In his latest iteration I believe that instructions are different.

      I have one sitting on my desk right now and haven’t quite gotten around to reviewing it yet!

  8. Tin Ramirez says:

    Hello, may we ask if you have a table relating PPM or mmol/L to the output of the Ketonix (which shows percentage)?

    Or, maybe you would know how to get the exact value of the acetone from the breath?

    Thank you for your future response, we need this for our study in our university.

    Yours in research and innovation,

    5th year electronics engineering student
    University of Santo Tomas, Philippines

  9. Tin Ramirez says:

    And also, may we ask how you got these values?

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

  10. Bob says:

    Thank you for the chart which helps me come close to figuring out when I am in ketosis using my new Ketonix analyzer. I have some thoughts about the variations in your test results.

    In searching for a way to correlate the numbers from the Ketonix with ketosis, I have read several other reviews and user comments reporting there will be variations depending on: 1) LENGTH of sample [how long you blow into the device]; 2) STRENGTH of sample [how hard you blow into the device]; SOURCE of sample [air coming from top or bottom of the lungs with higher readings coming from deep lung air]. I wonder if some of the variations you and others have experienced are attributable to one or more of those variables?

    If you use a watch with a second hand or a timer (many available online or as an app on your cell phone), users can time the length of their samples to achieve a consistent sample time. Blowing at close to the same strength isn’t too difficult and doesn’t have to be exact to produce fairly consistent results.

    But to get air from the bottom of the lungs where the higher concentrations of acetone reside requires some practice to know when to start sampling as you exhale. There is a natural tendency to take a big breath before blowing and that is the opposite of what you need to do.

    Although I have only had my new Ketonix Blue model for a few days, I find that if I exhale until I feel like I am about half way out of air before pressing the start button on the computer and then blowing for 15 seconds, I get more deep lung air with higher readings than blowing for 15 seconds from the top of my lungs (e.g., 63 vs 59). I also get a not unpleasant light-headedness which lasts for a few minutes after the test! But just to watch ketosis trending up or down, I could just consistently sample air from the top of my lungs; those samples are easier to replicate on a consistent basis.

    Hope this helps.

    • BJJ Caveman says:

      Thanks for sharing this. I haven’t been using my Ketonix lately because I’ve been messing with my cholesterol lately and haven’t been going into ketosis.

      But once I start, I’ll start fiddling around with some of the techniques you mentioned.

      I did notice a difference in the length of sample and strength of sample with the first iteration of the ketonix and with the sport.

      When I briefly fussed with the latest Ketonix I didn’t notice much of a difference in the computer measurements, which I surmised wouldn’t help the correlation with blood ketones. But it’d still be intersting to explore further.

      There’s also a new device… the levl

    • Ann Marie Whitley says:

      If you get this, I’d like to know if you would recommend this for someone that’s new to a keto diet. I’ve been trending downward over the last two years on carbs but definitely not this low. The lower I go the better I feel and recently figured out I’m really just eating too many calories. I’ve upped my fat intake while keeping my calories at about 1600-1800. I really feel good and want to continue this trend. I plan to use this device to see if this would help me track my ketones based on my macros I’m recording in My Fitness Pal to see exactly the effect of what I’m eating has from day to day. I’ve taken keto and low carb high fat recipes and entered them into MFP by serving so I know what it looks like from day to day. Any information you’d have to offer is greatly appreciated. I’m not looking for measurements as much as a range. CAVEMAN: If you have anything to offer on this subject, I’d appreciate it very much. This is a great post and you’re definitely on the cutting edge of where people are headed in terms of not buying in to conventional wisdom and government recommendations on nutrition.
      Ann Marie

      • BJJ Caveman says:

        Ann Marie,

        My thoughts are, if you think this is a tool that will help you stay on track and continuing to improve your health and well being, then it’s money well spent.

        It’s something you can use to have a general idea on how well you’re adhering to your low carb diet and whether or not you’re in ketosis.

        If you’re looking for something that’s as precise as blood ketone testing… then this wouldn’t be that helpful.

        • Ann Marie Whitley says:

          Thanks caveman. I think I’ll give it a try. I feel so much better eating this way and truly believe in it and that I can improve if I have something to measure it with. I don’t think it’s necessary, for me at least, to have that much detail. I just need to know I’m in the ballpark.

    • Joseph Leon says:

      I want to echo what Bob is saying. It is a skill to do the deep exhale after the regular exhale. But if you do that, you get consistent numbers. For instance, I can repeatedly get readings of 47,48,47,46,48, etc.

      I also want to question BJJ’s premise that blood ketones (beta-hydroxybutyrate) detect ongoing ketosis more accurately than breath ketones (acetone). According to the inventor of Ketonix, acetone is an immediate byproduct of ketosis. That is, the liver breaks down fatty acids > aceto-acetate > acetone and beta-hydroxybutyrate. The acetone then immediately leaves the body through the breath, and when ketosis stops, there is no more acetone. So the starting and stopping of ketosis is shown the most accurately by breath acetone. In contrast, the buildup of beta-hydroxybutyrate in the blood occurs over time and is less correlated to ketosis starting and stopping.

  11. Jani says:

    What I noticed when using ketonix:
    – The exact value isn’t linear, so there’s actually a huge difference in start(50) and end(75) of the default yellow zone.

    – My current breathing is not blowing air tight in it, no sound. This way I get to blow easily all the way without body getting into panic of breathing in.

    – If my blood glucose is near where the cells randomly burns either ketones or glucose (while in resting state), I’m not going to get any good plot lines or correlations.

    – When I accidentally ate too much (baked stuff, perfect macro numbers, but too tasty) for 2 days(double-triple calories), 3rd day and I guess my body storage was too full of glucose -> brain got too much(4.9(88)) -> spiked it up even more(5.9(106)) and I didn’t feel well for the rest of the day. Food alone couldn’t raise it that much from below 4.4(80). Ketonix was fluxuating between 59-67. It was 70-78 before, but that period was still learning to breath correctly in it. I instantly stopped extra carbs and day after ketonix went over 70 and raising steadily. Currently it’s 78-82. I have added heavy cream with berries again <)

    In short for me: Ketonix does show well, if I'm far away from burning glucose. From 2 months, my blood glucose average has been 3.9(70) and pretty stable, except above incident. I wouldn't search correlation between ketonix values and blood values, there's just too many random elements. So far it has shown me nicely, if I can eat more(the extra hunger!) and blood glucose staying down.

    • Jani says:

      Seems like it didn’t like some of my key combinations. This is what got cut:

      … with berries again, but haven’t done any bread and pie crusts, think they were too much at this stage(2 months in).

      – Had some intensive physical activity for ~10 hours, couldn’t test during it. But after all of it, blood glucose was 4.6(84)(just above usage level) ketonix 79. 30 mins of rest and glucose 4.2(76) and ketonix 78. I guess blood glucose being up is normal because of “not so slow” physical activity. Next morning blood glucose 3.2(58), ketonix 81 and pretty ok feeling for energy. (Some muscles did hurt thou).

      In short for me:…

  12. Mark says:

    How often do you recommend testing when using the blood strips? To stay cost effective yet at same time know where you are at ketosis wise?

    • BJJ Caveman says:

      I’d probably do it for 1-2 weeks straight just to get a sense of how your body responds. Then once you understand where you typically fall and how certain foods and activities affect your numbers, maybe once a week or so.

      And on those days when you fall off the wagon and you want to see how much damage is done.

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