4pm today BrAce: 3.4 ppm; Lumen 2 (burning mostly fat). This about an hour after finishing my shift at Walmart. I have an idea of what might be happening here and a way to test it.
Iām guessing that at rest or fairly low level of physical activity, there is an excess of acetoacetate breakdown and release of sufficient CO2 to skew RER upwards. At increasing levels of physical activity, there should be less excess of both acetoacetate and CO2, hence less skewing of RER. My n=1 so far seems to suggest this. When my BrAce has been 10+ ppm my Lumen readings have been skewed upwards. My last BrAce was much lower and my Lumen reading less skewed.
Although it was not busy during the first 3 hours of my shift, the final 3-4 hours were very busy. So physically, it was somewhat demanding. Since Iām fairly well fat-adapted, I suspect that my energy requirements were being met efficiently. That is, not much excess acetoacetate left over to break down into acetone and CO2. Hence, the lower BrAce reading. And RER less skewed upwards.
My previous breath samples with BrAce at 10+ ppm and Lumen 3-4 (burning carbs and mostly carbs) were taken at rest. The samples this morning before I went to work were less than 10 ppm, but still above 6 ppm.
How to test? Log BrAce and Lumen breath tests over a period of time to determine if there is a direct correlation between them. That is: BrAce down / Lumen down; BrAce up / Lumen up. Do the sampling at different times and intervals of physical exertion to produce different BrAce ppm results.
I have not done an extensive search of the literature, but what Iāve seen so far has been with athletes and exercised individuals, not at rest. I will continue to search and if anyone would care to do so as well, please post links to any/all studies of ketosis/RER at rest. Thanks.