Lumen - let the conversation begin š
The high carb might be just to get a baseline. Maybe you need high carbs? Could this, for instance, produce a certain result?
Like this for instance, where high carb is about 1:
Maybe this varies by person, so maybe youād get a 0.9 instead of 1? Then, the machine would know that 0.9 is (near) your maximum level.
First impressions. The Lumen App sucks. I just want to take breath samples. I donāt want to watch young ladies riding bicycles and sitting around in cheery apartments. I just want to make a measurement. Period. The voice over is 100% unnecessary and condescending, like Iām an idiot.
The ābreathing techniqueā is just as finicky as the Ketonix. But unlike the Ketonix, you only get 3 attempts and youāre done for the day. The app shuts down. All you can do from then is āpractice breathingā! I tried to ācalibrateā my fasted breath this morning but didnāt measure up sampling-wise, so now Iām prevented from trying again until tomorrow. It wonāt happen tomorrow, but maybe Sunday.
@ctviggen Good point about maybe using max VCO2 as the base line rather than min. I would point out, though, that the ācalibrationā starts with a measurement in the fasted state, so thatās producing a min VCO2 value. Maybe the max is then calculated to give the range of possible values. If I can get the damn thing ācalibratedā weāll find out, because I do not intend to ācarb upā.
Finally, Iām firing off an email to support to ask if they have a simple, nuts&bolts version of the app for us real bio-hackers who neither want nor need entertainment but just data.
This makes logical sense to me. Of course, logic doesnāt always work with the body.
This is what the RER of āvery low carbā athletes look like at rest, and at varying stages of exercise intensity. Notably, they were fed 15% carbs which is way higher than any of us. They were compared against athletes eating a diet of >50% carbs. Unless you are currently sprinting while breathing into the Lumen, how could it possibly generate useful data? All of our RERās are at around .75 pretty much 24hrs/dayā¦unless weāre sprinting.
The only way the Lumen could show a deviation from this is if it doesnāt work. Am I wrong? What am I missing?
@Don_Q As one whose level of exercise is probably going to stay at or not significantly much above āat restā in terms of your chart, I think its usefulness might be: (1) Do I have to stay sub-20 grams of carbs per day to stay in predominant fat-burn mode; or what exact grams of carbs bumps me out, 40, 50, 75 or like spacebunny 100+; (2) What happens if I eat sub-20 grams of carbs per meal and the total exceeds 20 grams per day; (3) If I eat a couple of large DQ vanilla cones, how long does it take to return to predominantly fat-burn mode; (4) If I have a couple (or more) shots of gin, how long does the ethanol prevent fat-burn; (5) If I go out with the boys for pizza and beer how long does it take to get back into fat-burn mode. I can probably think of a few more, but thatās a start. I donāt worry about ketosis, my primary concern after 3+ years is fat adaptation and how well thatās going. How well do I cope with various fuel inputs? That sort of thing. Whether RER is .72, .75 or .79 is of less concern to me. Although Iād love to have those numbers, I donāt think Lumen is going to give them to me.
Gotcha. That makes sense. Youāre RER wonāt vary on a ketogenic diet, but it definitely will after pizza & beer!
Wouldnāt a ketone meter answer all of those questions more cheaply and precisely though?
Ketone meter doesnāt tell me fat-burn. I can have a lot or a little on the meter, but still have no idea of how efficiently Iām burning it. I know Iām in ketosis most of the time and because I remain conscious and functioning relatively normally I must be burning ketones and fat efficiently. But Iām a gadget guy so having a means of measuring that is attractive. Even a first gen device.
The pizza and beer is not going to happen, but other stuff might and Iād like to know whatās going on when it does.
Beyond Lumen, assuming itās successful, others will follow and hopefully sooner or later we will have an unadorned RER hand-held meter.
Calibration
I managed to complete the ācalibrationā today. I ate my standard fair for the day, which included a total of 14.25 grams of carbs. At one of the breath samples after ādinnerā the app queried whether or not I had eaten the recommended 11 āmealsā (servings?) of carbs. I answered no which was followed a question of how many carbs I ate, to which I selected lowest option. Very little or something like that. There was no zero option or I would have selected that. Prior to each Lumen breath sample I sampled BrAce with my Ketonix to confirm I was in ketosis. Tomorrow my first Lumen day begins. I am very curious what the Lumen is going to report. And what happens when I eat some carbs.
Maybe not. I can (just did yesterday) eat ice cream and still be in ketosis a short while (a day?) later. Darn! All of my meters are at work, and I am at home, so I canāt test my ketones to see what they are.
First morning
I was unable to take an RER reading first thing this AM. Somewhere partway through the questionaire my device and app lost contact with each other so I had to abort. Iāll try again later after I get home from work. Iām wondering why all the questions re my lifestyle: how long I slept, what time I went to bed and got up, did I eat all my carbs yesterdayā¦ Does this devise actually measure anything or just do an esoteric calculation based on my answers to what is a very intrusive and to me pointless interrogation. Just measure the damn O2 in and the CO2 out, do the division and give me the result. Whatās so complicated about that? Anyway, prior to the attempt I tested positive for BrAce with my Ketonix.
It would be a really fascinating experiment to eat full sugar ice-cream, and track ketones + glucose + RER for every 20 minutes for the first 2 hrs. I donāt have a clue what would happen. Iām not sure how quickly ketones would drop off, or how quickly RER would change.
When I did a āmetabolic flexibilityā experiment a couple weeks ago after about a year of keto it was really fascinating. Just eating 100g of beans, which was around 60g net carbs, was like eating a jar of lightning. Prior to keto, I had struggled with hyperglycemia and hypoglycemia since my teens, so I have a strong frame of reference for what hyper feels like. This was off the charts. I was actually concerned it might be getting dangerous. It persisted for hours!
My theory is that because I do so much extended fasting, I have developed extremely strong physiological insulin resistance (the good, glucose sparing kind). Basically, my cells refuse to take sugar at the cellular level. At the same time, my pancreas barely even remembers how to produce insulin at the levels necessary to deal with such an event. The result is elevated glucose that has nowhere to go and just does laps through the bloodstream for a while.
In short, I think I was hyperglycemic while in ketosis for at least several hours, possibly more!
It would be fascinating to see which registered the transition out ketosis first, the Lumen or the meter.
I just asked if being on a purely carnivore diet with NO carbs will affect calibration. I am not biting any bullets
I just started measuring also. I am on a Carnivore diet of zero carbs. Letās compare results as we move forward. I also sent a message to the Lumen makers about how calibration is affected if you just donāt eat ANY carbohydrates.
Home from work and did a couple of Lumen breath samples. First tested for BrAce with my Ketonix. Although Iām only looking for a yes/no, Iāll mention that my BrAce was 10.4 ppm immediately prior to the first Lumen sample. Result: 3. I did a second test about 6 minutes later. Result: 4. Repeated 15 minutes later. BrAce: 10.7; Lumen: 3. Thatās pretty stable for BrAce, by the way. 
To give the Lumen the benefit of the doubt, I have been taking Dayquil for a couple of days to suppress my cough at work. It contains HFCS and probably other carbs. So letās say thatās showing up as the carb portion of my metabolic burn. While in ketosis? That would be interesting. Iām not going to take any more Dayquil as of 4pm PST. I will repeat the breath tests again when I get up a 5am tomorrow. If this is whatās happening, then the glucose should be burned out by then. I should reasonably expect the Lumen to show a 1 or 2.
On the other hand, maybe the Lumen is not actually measuring anything. Instead, itās performing some esoteric calculation of what it āthinksā my metabolic fuel āshould beā based on the incessant questions it continues to ask me. Iām going to start responding to the questionaires with contradictory responses to see if the AI will implode.
Canāt computeā¦
Canāt computeā¦
Canāt computeā¦
Please, donāt do that, Daveā¦
Iām going to give it a few days, at least until my current illness is over. Iām sure thatās screwing up stuff. But yes, I am going to write to Lumen support and ask them how to turn off the AI. I just want the device to measure O2 in and CO2 out, calculate and display the ratio. I donāt need nor want the lifestyle, meal plans, exercise, and all the rest of the crappola. Just the numbers.
Oh heck. Here I thought this thread title meant there were other hydro garden nuts on my keto forum. LOL
That thing sounds really interesting, if they can turn off the nanny-element.
Let me know what you find. They havenāt responded to me yet. Tomorrow is some kind of calibration day. I wonāt be following the garbage about carbs.