I’ve been following this thread carefully and am really intrigued by what’s been going on here. I am 31 year old, German male, and on a ketogenic diet for roughly 1 1/2 months. Until a week ago, I have only tracked my urine (that is spilled) ketones. They consistently show low, medium or high values (to this date!). I am probably someone who spills ketones in their urine even after being keto-adapted (which I think I definitely am at this point). I work out regularly (cardio 3-4 times a week) and have been eating less that 20g total carbs for a month. I vary my diet quite a lot, although I keep my carbs below 20g every single day and rarely, if ever, go beyond 60-70 grams of protein. My usual fat intake is between 130-200 grams. So I am practicing a classic keto diet very consistently and track my macros accurately.
I bought the AT6000 a week ago and have started to monitor my breath. During the very first attempt, I blew after exhaling completely and it showed a 0.00 (in hindsight, I conclude that was to calibrate the sensor or something). Afterwards, it has consistently shown values around 0.10 (lowest I’ve ever got) to 0.12. Interestingly, this seems to be rather uncorrelated to whether or not I am eating or have eaten. I am on a 24h fast so far and just found the same BAC (0.11) as yesterday morning and evening. The correlation with my urine ketones is loose as well. For those who are interested, I put in my values in an Excel spreadsheet.
Some tentative conclusions for me so far:
For the AT6000: exhale completely, then VERY(!) gently blow when the device is ready. For me, it takes 2 seconds max until the device has enough air the analyze my breath. For my girlfriend, who is not keto, I have found that she needs to blow for 5-10 seconds until the AT6000 analyzes her breath. She always comes up with 0.00. So it definitely works.
One marker to check, if you blow in too hard, is whether your breath condensates the display. This was the case for me the very first time I used it and it gave me the 0.00 BAC.
The AT6000 shows VERY consistent levels of breath acetone levels, provided you use the same breathing and blowing
technique every time. In fact, I have never been out of the 0.10-0.12 BAC range for the time I have used it
I seem to be pretty heavily in ketosis, because of the lacking correlation between breath acetone levels and when/if I have eaten. Given my varied diet (sometimes going fully vegetarian or even vegan some days), this is the only conclusion I can draw, because the device definitely works.
There is no correlation (so far) between acetone and acetoacetate levels for me. The former is very steady and constant, whereas the latter is all over the place and stronger hinges on water intake and other factors.
I think the lacking correlation makes sense to some degree: the acetone measures whether the body uses ketones, whereas the acetoacetate is more an indicator for ketone excretion. I conclude that I am fully keto-adapted, because the “ketone usage” indicator is so invariant
I would be curious what you think of my findings/conclusions so far. If interested, I will keep on sharing my data.