Anyone heard of Keyto breathalyzer?


Found this mentioned on theskepticalcardiologist’s blog, has anyone seen or used one?

(Tom Seest) #2

I’ve used that cardiologist, but not that meter…:blush:

(Michael - When reality fails to meet expectations, the problem is not reality.) #3

No, but I have and use a Ketonix. I think a little competition in the BrAce device market is good. However, I am a bit suspicious when I see direct comparisons between BrAce and β-hydroxybutyrate concentrations in blood, as portrayed in the linked article. They are not directly comparable and it is misleading to suggest they are. Converting x ppm BrAce to a corresponding equivalent x mml/L β-hydroxybutyrate, which is what this device apparently claims to do, is not possible.

BrAce is a product of the break down of acetoacetate. Since the break down of acetoacetate to acetone occurs at a known rate, the blood concentration of acetoacetate can be roughly estimated from the concentration of acetone in breath. However, many factors affect this and the signal derived from BrAce is very noisy and difficult to interpret usefully.

Ketonix, on the other hand, simply measures the concentration of BrAce in ppm. They accept that the concentration of BrAce and its relationship to blood ketones is not fully understood. Yes, if you’re generating more BrAce it suggests there’s more acetoacetate breaking down in blood. But that does not tell you anything about β-hydroxybutyrate.

I think this is a much more promising device. It claims to measure RER to estimate RQ. I think this is a much better and much more accurate way to measure fat burn and carb burn directly and in real time. I think ketone measurements are soon going to be obsolete.

(Cancer Fighting Ketovore :)) #4

For example, today I couldn’t even get the Ketonix to register that I was breathing into it… :frowning:
However, my PrecisionXtra recorded my glucose as 96 and ketones at 0.9, while the Walmart Reli-on BLU recorded my glucose as 89.

Really they need to tighten up the error rate for these things.

(Boston_guy) #5

I’m going to give this a try. I work from home in a non-keto household, so plenty of carbage around. Hopefully this will clean up my dirty Keto.

Hardware-only option is $99. No consumable strips, so this seems like a good deal.

Dr. Andy Phung likes it:

Interview with the founder – gamification/addiction for behavior change. Inspired by watching his daughter use Snapchat

A user showing the device and tracking levels over time -

(Boston_guy) #6

Chomping at the bit for this to arrive, heh. My fructosamine was on the high side and this should help keep me on the straight and narrow.

Dr. Christian Assad says that the Keyto device gave the same result 10X in a row - very consistent. Unlike KetoMojo.


Hey! I was just wondering if you received the device yet and are happy with it? I was curious about it’s accuracy and usefulness.

(Bob M) #8

The issue will be that breath and blood (or urine, if you want to add those in) don’t really track each other. As gross measures of whether you are in ketosis, they work, but if you really want to test things, they fail.

I’m currently using only my first-generation Ketonix, and I can get low values when eating nothing but basically meat, but I’ll get higher values for certain situations, where I happen to have more breath ketones. Eating a lot of fat seems to help (extra fat being converted to breath ketones). Fasting can help, too, but not as much.


I’ve been doing keto and IF since April and I’m at the point now where I can usually tell when I’m in ketosis. I do have heavier carb days about once a month. I’d like to be able to tell when certain foods effect the level of ketosis I’m in. I don’t need it to be super accurate beyond ____ food = ____ level of ketosis/ or knocks me out etc. I have suspicions about certain net carb things I’m doing and sugar substitutes and would like a better idea of how much it’s really effecting me.

But I’m kind of scared of blood meters so I thought a breath meter might work. Thoughts?

(Boston_guy) #10

@Seawitch Yeah, I’m loving it. Checking it multiple times a day.

In terms of accuracy, the readings are rock-solid. If I take a measurement then repeat it, it’s the same.

Highest I’ve gotten to is 7 (range is 1-8), on a day with MCT’s.

Overall I’d say it’s A+. Quick inexpensive and portable. Very good tool to keep you honest and make cause&effect evident.

(Bob M) #11

I think that should work. See here:

But see this:

These are from my Ketonix. I find it a bit hard to believe that I wasn’t in ketosis on some of these days. My Ketonix has a setting of “green” ketosis is 25-50, yellow = 50-75, and red = 75+. There are multiple settings, and mine is “sport”. For “nutritional” ketosis, the “green” does not start until 40.

However, I’ve been low carb/keto since 1/1/14, so my values are much lower now than when I bought this about 4 years ago. It was much easier back then for me to hit 60-70+. Now, not so much.


Oh great! That’s really what I’ve been looking for. Thanks! I’ll have to get one of those and try it out.


Great! Thanks so much for the response. I was wondering about the reliability. I’d hate to invest time and money on something that doesn’t read right half the time.

(Michael - When reality fails to meet expectations, the problem is not reality.) #14

A couple of additional comments. First, to reemphasize what I said above:

I am a bit suspicious when I see direct comparisons between BrAce and β-hydroxybutyrate concentrations in blood, as portrayed in the linked article. They are not directly comparable and it is misleading to suggest they are. Converting x ppm BrAce to a corresponding equivalent x mml/L β-hydroxybutyrate, which is what this device apparently claims to do, is not possible.

From your descriptions, it seems like this device is measuring BrAce (or maybe not), doing a calculation of some sort based on a presumed conversion factor, and giving you a number that you interpret as a measure of β-hydroxybutyrate. This is not possible. Thus, I am very suspicious. The numbers you quote are the same numbers that all cheap breathalyzers give you and they are measuring acetone (possibly), ethanol and/or probably isopropanol. This has been discussed on the forum in multiple topics.

This is why it’s not possible to measure BrAce to determine β-hydroxybutyrate. Acetoacetate is the fundamental energy packet ketone. β-hydroxybutyrate is a more stable, storage form of acetoacetate. The two spontaneously convert back and forth into each other. It is not known exactly why so, but I suspect it’s related to the concentration of β-hydroxybutyrate which maybe your metabolism is trying to maintain at some level. Or something else. Thus, the relative concentrations of acetoacetate and β-hydroxybutyrate in your blood at any given moment change constantly. If you were doing frequent blood tests or had a continuous monitor you could track the changes and their magnitude.

Acetoacetate also spontaneously breaks down into acetone, which very quickly either evaporates out through the skin or is exhaled along with CO2. Since acetoacetate has a known ‘half-life’ we can use exhaled acetone as a rough proxy for acetoacetate. But other than its source being the same, there is no connection between the amount of acetone being exhaled and the concentration of β-hydroxybutyrate in the blood.

Also, BrAce is a very noisy signal. Getting ‘rock-solid’ and consistent results does not sound realistic. I find that additionally suspicious. When I attempted to calibrate my cheap breathalyzer against my Ketonix, it proved impossible simply because the cheap breathalyzer had such wide overlapping ranges for the results.

@Seawitch, if you don’t want to donate blood you have two options right now: Ketonix or Lumen. The Ketonix will measure BrAce in ppm acetone and show you the actual ppm concentration. The Lumen, which is just coming to market, measures the ratio of fat/carb burn in real time, based on the direct measure/calculation of RER.

Personally, I’m betting the Lumen obsoletes direct measurements of ketones, except for specific medical conditions where knowing the β-hydroxybutyrate blood concentration is necessary.


Good day, I have been using the “KEYTO” breathalyzer for 2 months and find it to work quite well. It does cost $100.00 but that’s it. I started using it because I’d loose 10 pounds for a couple months and then plateau, not sure why I’d plateau, but wanted to make sure I truly was in ketosis, if nothing else, it just makes me feel good to know for sure I’m good.

(Michael) #16

I use the Ketonix several times a day. If I get a zero reading there is normally a reason for it and that generally is that I am getting ill, normally a cold. Blood ketone readings don’t definitely confirm that you are actually in a state of predominantly burning fat. Low blood glucose levels will normally be a positive sign in conjunction with the presence of blood ketones.

I think Bob makes a good point. Yesterday afternoon my Ketonix did not register any reading.
It so happened that I had no breakfast but had Greek yogurt with loads of blueberries at lunch, so the blueberries put an end to ketosis. However, by this morning I recorded Acetone at 22 PPM. I suppose it did help that I also had 140 grams of Olives at yesterday’s lunch in spite of later having some potato gratins at 7pm. I associate the high levels of acetone this morning to the olives at lunch yesterday.

The moral of the story for me is that there is a reason for zero readings on the Ketonix.
Either not being in ketosis or being ill.

(Michael - When reality fails to meet expectations, the problem is not reality.) #17

Another reason is having blown all the acetone out of your lungs. I have to wait at least 60 minutes between samples otherwise I get very low and/or zero readings.

(Cancer Fighting Ketovore :)) #18

So, how low is low? A little bit ago I tried checking my BrAce and got 1.2PPM. I’m about 17 hours fasted. The reading from my FreeStyle Libre was 74 mg/dL, Precision Xtra BG: 81, ketones 0.6.
So, is this saying I’m not predominately burning fat/not in ketosis?

(Cancer Fighting Ketovore :)) #19

So, depending on what hole setting i use I can change the reading a bit…
I just tried it after eating around 9pm (i think)…I also had coffee (not common for me), and just now I’m getting about 13ppm. Its certainly interesting, but hard to get that “last bit of breath”…

(Michael) #20

A zero reading is a problem. It I measure zero I will more than likely be ill within 2 days. It came to pass for me over the weekend that I have a very mild cold.

I had a very stressful and busy week so that may be a contributory factor.

From my experience a low blood sugar level is a positive indicator but it will vary throughout the day no matter what. Blood Ketone levels tell very little especially at lower levels.

The body gets accustomed to dietary changes over time and as a result it’s response will be modified over time. I believe acetone (BrAce) is an outlier in this situation as it escapes through the skin and the lungs because it is so volatile. The body is not able to contain and regulate it like blood glucose and blood ketones,

Remember that blood ketone levels are only a measure of what is available for use not a measure of what has recently been burned as BrAce is.

No doubt there will be naysayers that say this is all nonsense but these commentators usually have no personal experience of measuring BrAce or anything else for that matter. Beware of the advocate who misleads.

The breathing technique is the most difficult to master. If you follow the advice on the Ketonix website you are likely to go blue in the face. Always use the larger hole to make it easier to blow into the device.

My technique is as follows:

Take a few deep breaths and then make sure to get one’s lips sealed around the mouthpiece and begin to blow. Don’t be afraid to breathe in through your nose while blowing. Eventually you will get to a stage where you can empty your lungs comfortably and save the reading.

As regards levels you should ideally be above 4 but anything above zero is an indication of low level background ketosis. For therapeutic levels, the higher the better though. I rarely go much above 30 following my current diet. I do not do any fasting at the moment and I do not aim to be in ketosis all of the time.

My readings for the last six weeks are hardly stellar but I am happy: