Lumen - let the conversation begin 😋

[jennasaurus]

I’m sorry that you’ve been sick for so long. I think you’re right to connect this to your lower ketone levels and higher RER. While it sucks that you’re sick, I think we can learn something from your n=1. You said that in the spring/summer your BrAce was between 20 and 40 and recently your BrAce was 9.4 and Lumen 2 (and I understand your Lumen readings have been higher than that too).

My understanding is that your immune response is probably requiring a pretty constant supply of glucose to fight your illness. The interesting thing is, you are still in some level of ketosis even though it is a lower level than you are used to. Maybe this means that you are producing ketones to fuel your brain while also producing glucose to feed your immune response. That’s kinda amazing if it’s what’s happening. I hope you get better soon (and not just so we can see how your numbers change)

[EZB]

Well that is an interesting response. If you don’t want to eat carbs, just do a caloric deficit? I wonder what a 7-day fast would do

[EZB]

Also… in the zero-carb meal plans is grilled duck breast with butter-glazed carrots. Do they know what a carb is?

[Don_Q]

I’m trying to establish, using BrAce as a marker whether or not the Lumen is internally consistent with the values of BrAce. This to test my hypothesis and to see if we can actually get any useful results from this device. My initial assumption is that BrAce is somewhat consistent with level of activity. That may or may not be true.

@amwassil

I’m really intrigued by this idea, and your use of the Ketonix to correlate BrAce with the Lumen. You mentioned the use of cough syrup, and that you’ve been ill recently, and how you wondered how that might affect readings. You could be on to something. This article might be a piece of the puzzle. It summarizes ways in which certain foods and medications and other factors can affect BrACE levels within the body:

https://onlinelibrary.wiley.com/doi/full/10.1002/oby.21242

[amwassil]

I think I’ve discovered a significant effect over the past two days re medication that affects RER, at least as measured by the Lumen.

As mentioned previously, I was taking some fairly large doses of Dayquil and Nyquil, both liquid and caplets to control my coughing. It enabled me to go to work and function. I stopped all *quil as of Feb17, prior to 4pm. I tested 0218: at 4pm, 7pm and 9pm. Results were all 2 on the Lumen. So my guess is that most of whatever the cough syrup was dumping into my system was metabolized out. I don’t think all of it yet, otherwise I suspect I would have blown 1s not 2s.

Last night (Feb18) before bed at 11pm I took a single Mucinex tablet. I also ate about 5 grams of raw ginger root just before taking the tablet. Today, I ate about 20-25 grams of raw ginger root (4-5 grams of carbs total) during my work shift to keep coughing under control. It worked, however, I’ve tested 3 times today, 0219: at 5am, 3:30pm and 5pm. Results were all 3 on the Lumen. So either the Mucinex and/or ginger root have boosted CO₂ again. I hope not as much as the cough syrup.

I am off both tomorrow and Friday, so I do not have to medicate myself to prevent coughing. I am hoping that a couple of ‘clean’ days will burn out whatever is still lingering. Also, the wife and I are going to our local rec center tonight, she for swim lesson and I for the sauna and hot tub. So maybe I’ll blow some 1s before the weekend.

[amwassil]

I’ve been wondering about ‘calibration’ and I think I’ve figured out what’s going on. First off, what’s to ‘calibrate’? If you measure O₂ in and CO₂ out, RER is just the mathematical ratio of those two values somewhere within the range of .70 to 1.0.

So why didn’t Lumen just design and build a device that calculates absolute RER? I think because the market for such a device would be fairly limited. Us gadget guys and gals, maybe some university labs and training facilities and a few top athletes.

But if you build such a device how do you market it (and make big bucks) to a wider audience who probably don’t know and likely don’t care what RER is? But who do care about losing weight and probably need help to do it. You market a consulting service based on using said device as a yard stick and gimmick.

Average overweight Joe and Jill eating some variation of SAD don’t have a realistic RER range much beyond .80 - .90 and probably spend most of their lives at .85. So there’s really no need to display the absolute range of RER. You only have to give Joe and Jill something attractive and encouraging to look at multiple times per day.

Thus: Calibration! You have Joe and Jill fast overnight to get whatever the lowest RER they can blow. If they actually get into ketosis, great. But it’s not necessary, we just need a relative min value. Then during the day we have Joe and Jill carb up to get whatever highest RER they can blow by the end of the day. Again the absolute number does not matter, we just need a relative max value. Then our ‘smart’ software takes the min and max values, divides the range into 5 equal segments. Voilà! A customized, calibrated RER value set.

So what happens when some smart aleck like me comes along who’s been in ketosis for 3+ years and has no intention of carbing up. The device still calibrates a min and max value and divides the range into 5 equal segments. But in my case the range is probably something like .72 - .76.

What do you think? Plausible?

[Polly1]

More than plausible, @amwassil I would say probable that you have hit the nail on the head!

When I read the letter they had emailed to you yesterday, I actually wondered what the device was measuring and calculating at all but now you have seen through the smoke and mirrors it makes sense to me.

Well done.

Will you now record your data in a spreadsheet so it can do what you want it to do?

[EZB]

Sadly, that’s the nail in the coffin

[charlie3]

So might there be some company out there that sells a meter that’s a straight forward device? Has anyone looked for that? These days I’m doing a lot of Maffetone style cardio with the goal of getting more fat adapted. Measure of progress is gradual increase in load at an unchanging heart rate. Would be lovely to have a second measure.

[amwassil]

@Polly1 I think the Lumen hardware is measuring/calculating actual RER. From this:

Currently the application does not provide metrics such as RER to users…

It’s the software that displays the result of the measurement to the user on an arbitrary scale set initially by the min/max values calculated during ‘calibration’. Thus, the actual RER values are there, just not displayed. For average Joe and Jill the actual RER will likely/almost certainly fall within the arbitrary range set at calibration so whatever of the 5 displayed segments is closest to the actual RER value is highlighted. If all you care about is whether or not you’re burning some fat, that’s good enough. It’s also not very accurate. For example: if your personal range of RER is .80 - .90 and you blow .82, the software is going to display 1, burning fat. When in fact, you’re still burning mostly carbs, just relatively a little less. So Joe/Jill are happy. Eating a little less carbs per meal works! I suppose it does over time at least better than not eating less carbs.

@EZB I think it’s only a ‘nail in the coffin’ if you want actual RER values displayed. The Lumen won’t do that now. However, it may eventually do so:

…metrics such as RER to users, however, may do so in the future based on user requests.

I think having a hand-held RER device at sub-$300 is quite an amazing accomplishment. Modifying the software to display sampling results in different ways is trivial compared to designing and building the device capable of delivering accurate measurements. If, in fact, Lumen might actually do this based on user requests, I’m willing to stick with it, learn to live with the current limitations and figure out how to utilize it usefully while waiting further utility down the road a bit.

@charlie3 As far as I am aware at the moment, Lumen appears to be the first such device but see above:

Lumen - let the conversation begin

No it does not make sense, nor is it plausible. $50,000 metabolic carts don’t seem to have that problem measuring RER. See the study on RER in ketogenic diets linked about 20 posts up. The only issue I can recall with RER measurements in a metabolic ward was in a fasting study. After like 8 days of water fasting, the subjects started exhibiting RER’s of 69 or something like that, which is not theoretically possible. It was something to do with some strange feature of ketone metabolism in supe…

Lumen - let the conversation begin

I wish! I’ve got the budget model. I’ve been underwhelmed by it’s RER measurements, which is why I am skeptical of the lumen. The study I linked earlier took a baseline for all athletes at rest. The “ketogenic” subjects blew a .76. Bear in mind though, they had to eat a 15% carb diet in this study (don’t ask me why they call that ketogenic), and given that these were 180lb athletes at 11% bodyfat, I’d guess that TDEE was easily 3000kcals. This would give us 450kcals, which is 112g carbs. I do…

Lumen - let the conversation begin

I think that makes sense. I’m not trying to bust your chops or belittle the Lumen. My rig sucks for RER too. It had me at .75 while 3 days into a water fast. That’s not even humanly possible. Even the one’s in metabolic wards struggle with RER once deep ketosis comes into play! I’m stuck with my rig, but you’re not stuck with the Lumen. Either it can measure the RER of people in ketosis or it can’t. It seems like it’s giving weird readings that don’t make sense to either of us. I think the Lum…

[amwassil]

0220:12p I just blew my first 1. BrAce was 16.9 ppm. This is interesting because my first sampling this morning at 8am BrAce was 12.5 ppm and Lumen 4! Dawn Effect? Residual debris from medication, ginger root finally gone?

For the time being, let’s assume I’m correct in my interpretation of the ‘calibration’ process and my arbitrary range of RER values is something like .72-.76. That would translate to this:

1 =< .72 2 = .73 3 = .74 4 = .75 5 => .76

Because this is such a narrow range, I can expect very small things to have very noticeable influence. Like, exactly how much raw ginger root will bump me up by one segment? What happens when I take a Fisherman’s Friend to suppress my cough, which is still with me, but not so bad anymore? What happens if I eat 20 grams of carbs today instead of my usual sub-15 grams, or 25 grams (yikes!) Lots of little stuff like this to explore.

[EZB]

I have only gotten two 3s so far. I eat carnivore. It sounds like it will never work for me because it thinks my range is so limited

[amwassil]

Just a guess, but maybe glucose metabolism due to your T2D is adding sufficient CO₂ to keep your samples elevated. Keep in mind that if you did the ‘calibration’ with the 10+ hour fast and then ate zero carbs the whole day, your ‘range’ is likely just as constricted as mine is and maybe even more. So even a very small amount of metabolized glucose could affect your measurements.

Possibly some others more knowledgeable about T2D can advise how to reduce glucose and then you could determine whether or not that affects your measurements. I think it would be a worthwhile challenge for you to blow a 2 or 1. But keep in mind the support person who responded to you, said your results are going to be skewed and not necessarily be based on food intake. That’s says glucose to me.

Do you take medications? That’s suspect #2.

[EZB]

I’m not on medications for diabetes. I think the support person gave a canned response as a cover. I suspect that it just builds a range through calibrations. So it will ask your to carb up to measure you as a carb burner. Then it makes you eat keto to measure your fat burning. I bet if I did do that and then went back to ketosis, it would say I am burning fat. However, because my “carb burner” calibration was done as a fat burner, it placed the top of my carb range as my normal levels.

[amwassil]

0221:1140 BrAce: 30.2; Lumen 1.

[amwassil]

I’m not on medications for diabetes. I think the support person gave a canned response as a cover. I suspect that it just builds a range through calibrations. So it will ask your to carb up to measure you as a carb burner. Then it makes you eat keto to measure your fat burning. I bet if I did do that and then went back to ketosis, it would say I am burning fat. However, because my “carb burner” calibration was done as a fat burner, it placed the top of my carb range as my normal levels.

I suggest you communicate with Lumen support again and ask how to recalibrate the device. Then do it the way I did. 10+ hour fast for the initial sample, then do not carb up at all for the samples during the day and post supper. If you do that, maybe it will help us determine whether or not your diabetes is confounding the samples.

[amwassil]

@Don_Q I think an interesting experiment is in order. That is try to test the validity of the range I’ve estimated above. I’m off Thursday and Friday of next week again, and finish work at 2:30pm on Wednesday. I could fast from post meal Wednesday (about 11am) then see if and how long it takes me to blow consistent 1s on the Lumen. If I can accomplish that, then I’d be very confident that ~.42 is the low RER value of my range. From blowing a series of 1s, the next step would be to break the fast with something like 10 grams of ginger root (1.8 grams of carbs) to see if the reading goes up. If not, eat 10 grams more. At some point the measurement will go up. Maybe? What do you think?

[Don_Q]

You’ve been keto for so long that your current glucose metabolism might play a confounding role. You most likely have glucose sparing physiological insulin resistance at the moment, so it can’t be taken for granted that your cells will accept the glucose normally. Blood sugar could remain elevated while it does continuous loops looking for a home for a while rather than being metabolized. Ergo your RER won’t be elevated until blood sugar drops (post-spike). You’ll feel the hyperglycemia immediately, but the cessation of hyperglycemia is more subtle.

Do you have a blood glucose monitor and/or a blood ketone meter? Measuring blood glucose will tell you whether the glucose gets stuck doing loops through your bloodstream.

My suggestion would be to avoid ginger, and just eat pure dextrose, which is the simplest and fastest metabolized sugar. Smarties candies are basically 100% dextrose. Each package is 5g if I recall. I’ve used it for experiments in the past. Fair warning, it will feel a bit like eating a jar of lightning for a little while. If you can’t find Smarties at Walmart or elsewhere, just do 5g of pure table sugar. Ginger may have some other effect that further confuses the results.

That’d be my two cents. I know so little about this stuff though, it might only be a penny…

[EZB]

They said I can’t calibrate it… I just blew a 4

[amwassil]

They said I can’t calibrate it… I just blew a 4

I’m presuming you mean ‘recalibrate’, and that’s unfortunate. I can think of multiple reasons to recalibrate the device periodically. So I think it’s definitely lacking a necessary feature. I mean, I can recalibrate my digital food scale as often as I like. Maybe if enough customers communicate that they pooched the initial calibration and would like to redo, we’ll see this function added. I think this would be a software mod, not a hardware mod. And probably trivial.

Before deciding conclusively that the device is not working for you and won’t work for you, I think you ought to try what I’ve been doing the past several days. That is simply take many samples during the day to see how the results change. They should, since I’ve already determined that in my case even very small changes affect apparent RER. Especially over a very small range of values. Maybe you’re already doing this? In your circumstance, I would fast for a day or two to see if that drives down the numbers. It should and if it doesn’t then I would suspect that your glucose metabolism and its idosyncracies are the problem. Do you have a glucose meter? You might be able to correlate the Lumen results with simultaneous glucose tests.

If it ends up that the Lumen is just not sophisticated enough to deal with T2D, at least you would have given it a good shot demonstrated that fact.