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[[File:Breath meters.jpg|right|thumb|200px|The breath acetone meters I've tested in detail.]]Acetone is produced when your body is burning fat, and this can be measured in your breath. There are now a growing number of options for measuring your breath acetone. The devices vary wildly in price, and while I've found some of the cheaper options may can be problematic, they may still be worth consideringquite effective. In all cases, how you breath breathe when taking a measurement is critical to getting a consistent and accurate reading. Overall, I found that measuring breath acetone to be far more convenient, and far more useful than measuring blood ketone levels. Measuring breath acetone is vastly cheaper than blood tests, and obviously less painful. This allowed me to check my ketone levels throughout the day, enabling me to find more detailed information about how my body reacts to food and exercise. * The best option at the moment would appear to be Ketonix, which is an FDA approved device that is designed specifically as a breath acetone meter. This is one of the more expensive devicesonly device that will give you an acetone reading in Parts Per Million, but if you want a degree of accuracy is expensive and I found itto be cumbersome to use and I's probably worthwhileve experienced more erroneous readings than with cheaper devices.* A cheap breathalyzer can be used as an improvised breath acetone meter. While these devices are intended to measure alcohol intoxication through breast measurement, the cheaper devices also detect acetone. This means you have to get a cheap, low quality breathalyzer, as the better devices will filter out any acetone. (I like the Greenwon AT6000, <jfs id="B0111EKF4O" noreferb="true" nonl="true"/>).

The Ketonix is designed to be a breath acetone meter, for use with the [[Ketogenic Diet]]. While it's designed specifically for acetone, the documentation does mention that it will pick up alcohol in your breath as well, so it's similar to a cheap breathalyzer in that sense. A number of users have complained about inconsistent readings, but and while I suspect that's most of this is due to breathing patterns , I've also had some issues. The Ketonix requires a long and variable warm up time, usually between 2 and 10 minutes, plus needing to be powered up for 2 minutes after taking a reading, making it cumbersome. ==Testing The Ketonix==The Ketonix feels like a medical grade device, made out of high quality materials but lacking the polish of a consumer grade device. If it were a choice between the Ketonix and blood ketone testing, I'd highly recommend the Ketonix as a vastly superior solution. However, having compared it to the cheap breathalyzers, I'd recommend buying the cheap breathalyzers. The Ketonix is obviously the best choice for clinical or research settings, but the only significant advantage the Ketonix has over the breathalyzer for casual use is its ability to read low levels of acetone. * '''Start up'''. In my testing, I found the warm up period really annoying. Having to wait 2 to 10 minutes for it to start up and get up to temperature makes it impossible to use to check your acetone levels during a run, and at other times it makes the test excessively time consuming. The manufacturer doesn't recommend leaving it plugged in all the time, so that's not a solution. * '''Tethering'''. The Ketonix can be used without being connected to a computer, but it will just flash a colored light to give you an idea of the acetone range. To get a numeric value you have to have it plugged into a computer (see belowthe latest version supports a smartphone via Bluetooth.) * '''Erroneous Readings'''. Using the rebreathing technique (breathing into a bag five times) generally gave me highly repeatable values, but about 1 in 20 readings were erroneous. I've not been able to work out what the underlying cause of these erroneous readings might be. The initial indication of an erroneous reading is that it's out of line with all the other tests, such as urinalysis, blood BOHB, the other acetone breathalyzers, and my general expectation. I typically find that simply repeating the test gives me a second result that's extremely close to the initial erroneous reading. If I disconnect the Ketonix is and restart the software (sometimes a couple of times) the reading will dramatically change to be in line with expectations, and the new readings are quite priceyrepeatable. It seems like the Ketonix has a bad baseline or calibration, but may I don't need to recalibrate to resolve the issue. I contacted Ketonix support and they were very responsive, but unable to offer any suggestions unless I could come up with a repeatable process for replicating of the error.* '''Correlations. '''I found the Ketonix results were surprisingly well correlated with blood ketone testing. It's critical to remember that breath acetone and blood BOHB are testing two different [[Ketones]], so you'd expect some difference. The main ketone is Acetoacetic acid (AcAc) which can be worthwhile if you want accuracymetabolized by the body, and both of blood and breath testing are measuring "secondary ketones". BOHB can be thought of as a ketone storage bank, and acetone can be thought of as a side effect of AcAc. The [[Ketone Levels| relationship between BOHB and AcAc]] can vary widely, from 1:1 up to 10:1, making AcAc a better option than BOHB. The research I've found indicates that Acetone and AcAc generally have a stable relationship. Ketonix suggests a value of 40 to 80 PPM indicates a statue of nutritional ketosis, though I found my levels were far lower, with 10-40 being ketosis. <br/> [[File:Ketonix BOHB. jpg|center|thumb|400px|My BOHB blood tests against Ketonix Acetone PPM]]==Ketonix Versions==There are several generations of Ketonix:

A good quality breathalyzer will only measure breath alcohol content, screening out any acetone that's present. However, the cheaper breathalyzers that use a simple silicon sensor don't to distinguish between alcohol and acetone. This makes them an interesting option for checking breath ketones, and I've tested several different types. One obvious conclusion is that because you're buying a remarkably cheap device, quality is rather poor. I had one device that just gave random readings, even with the rebreathing technique mentioned below. I haven't yet been able to compare ve tested these cheap breathalyzers systematically to the Ketonix, but I and found a reasonable good correlation between their readings them and Ketonix as well as with blood ketone testing. Here are some suggested devices:* Greenwon AT6000. This small handheld device shows Blood Alcohol Content (BAC) to three decimal places. That's nice to have, as BAC values I've measured are typically in the range 0 to 0.0813, so the AT6000 provides two an extra significant digitsdigit. If you're BAC value is above 0.05, it will be loudly and repeatedly to warn you that you're too drunk to drive. This , which is really annoying if you're stone cold sober. All these cheap breathalyzers have a warm-up period for their sensor, and the AT6000 counts down from 100, taking about 20 seconds. The AT6000 is sold by various companies on Amazon, including <jfs id=" B00M3MDD98B0111EKF4O" noreferb="true" nonl="true"/>.* Greenwon Keyring. This is a smaller version of the AT6000, though the size difference isn't all that great. It only provides BAC values to two decimal places, and it warms up in 10 seconds. It's a little cheaper than the AT6000, and its beeps are really quiet, something that I appreciate. <jfs id=" B00VFWWNXO" noreferb="true"/>.

File:Greenwon AT6000.jpg|The Greenwon AT6000. <jfs id=" B00M3MDD98B0111EKF4O" noreferb="true" nonl="true"/>.File:Greenwon Keyring.jpg|The Greenwon Keyring. <jfs id=" B00VFWWNXO" noreferb="true"/>.

==BAC Values and Acetone ConcentrationsTesting The Breathalyzers==ItI tested these cheap breathalyzers for about a month, comparing them to occasional blood ketone levels as well as the Ketonix. I have been impressed by how effective both the Greenwon breathalyzers are at measuring acetone levels. Using the rebreathing technique provides a little more consistency, but it's unclear how to relate BAC values from not critical if you're just after a cheap breathalyzer reasonable estimate of your ketone levels. I have found that the Greenwon sensors tend to acetone concentrations in read zero if your ketone levels are quite low (mostly below 3 PPM). One rough estimate is On the whole, I much prefer using these cheap breathalyzers to multiple BAC by 170the vastly more expensive Ketonix. The cheap breathalyzers warm up in a fraction of the time, but and if you've got re doing the rebreathing then the warm-up time is about the same as the multiple breaths you need before taking a reading. These cheap breathalyzers also have a built-in a display and are battery powered, so they're completely portable. There also cheap enough to have two devices to cross check. I'd recommend getting both the key ring and the AT6000. <gallery widths=400px heights=400px class="center">File:AT6000 BOHB.jpg|The AT6000 actually has a better correlation with blood ketone levels than the vastly more detailsexpensive Ketonix. Of course, measuring breath acetone and blood ketones are measuring two different things, so it's important not to assume that the AT6000 is necessarily better, please let me knowbut it's at least somewhat intriguing. To translate File:AT6000 Ketonix.jpg|Comparing the AT6000 blood alcohol content (BAC) readings against the idea Ketonix PPM readings, you see a pretty good correlation. The main issues you'll notice are that the AT6000 tends to read zero at lower ketone levels, and a one pound (0small number of readings that are some distance off the line.5 Kg) per week fat loss correlated I suspect that these are actually erroneous readings from the Ketonix, rather than problems with 1the breathalyzer.File:Keyring and AT6000.jpg| As you might expect, the Keyring and AT6000 provide fairly consistent results.</gallery>=Converting Ketone Values=My testing has produced some initial indications on how blood BOHB and breath acetones might interrelate. This is useful as most research provides blood BOHB values, and the definition of "nutritional ketosis" is typically given in BOHB concentrations.7 My readings suggest that dividing Ketonix PPM of acetoneby 12 is roughly my BOHB concentration, which means that the threshold of [[Ketone Levels]] of 0.5 mmol/L BOHB would be a about 6 PPM. My readings suggest that multiplying breathalyzer BAC of by 40 is roughly my BOHB level, meaning 0.5 mmol/L BOHB would be about 0.01012%BAC. (That's on a non-Ketogenetic dietDividing my Ketonix PPM by 450 gives my breathalyzer BAC.)