Lumen Breath analyses for metabolism

Has anyone used/tried this Lumen

The devices measures your metabolism via your breath to whether you are mostly burning fats or carbs. Also then gives diet options based on your target loosing weight, performance etc.


I’m certain someone here has posted about it - or maybe I saw on social media.

Maybe @Guystapleford? He is usually a good source of info on this type of thing :slight_smile:


I did try searching the posts but didn’t find any mention of it. Just ordered it so will see what I think.

As I fast I am interested to see what it says regarding me burning carbs or fats. Also especially around training. For example if I do an easy session I should mainly be burning fat not carbs especially if I am metabolically flexible. However a higher carb based diet should in theory have someone been less flexible and more reliant on carbs and therefore need a constant supply in order to keep that level of exercise.

So certainly for someone looking at longer endurance events been able to operate at a higher load while still mostly burning fat would be very desirable.

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Looking forward to seeing what you think!

Also following this with interest

Well so far after using it for a few days it looks like I am metabolically flexible.

It would appear that my diet has me in a good place not been overly carb heavy and a good balance of protein and fats. I do shift my days between been more low carb and high carb depending on the training. Carbs before harder training sessions and regular do low carb/fasted training.

So for me at the moment I will still keep testing it as after all I’ve a 30day return window.


Very interesting. Please keep us informed of this. Thanks!

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@kevstorr once you know how your metabolism functions, what is the ongoing benefit of the Lumen?

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Thats just where I am with it at the moment.

  1. I think it gives a level of accountability. Not sure the on going cost is worth it myself.
  2. They do seem to promote the idea of adjusting you daily macros based on your measurements and also you targets. So it will say it’s added 30g of carbs or so based on the exercise I’ve recorded. So checking in post workout if you’ve been logging your food and also what your in take was during the workout you can adjust your daily plan.
  3. It does give meal ideas based on your daily macro calculation but for me the daily shifting can make meal planning harder especially if you tend to go for more fresh ingredients. Still trying to see how this is any good for me.
  4. I think for the majority of people it would be a surprise to see your not actually as flexible as you might think and that you are eating a lot more carbs than you also think.

30 days for most probably isn’t long enough to make changes and learn. For me its confirmed what I’d hoped, given my fasting and daily macro adjustments.


Great feedback. Thank you so much for this. Perhaps worth a try, but maybe not long term for me.


Thank you for the feedback!


I use a Lumen. Accountability has been mentioned which is appealing to me, and it’s also a form of discipline to me but perhaps the most ‘interesting’ use for me is to see the impact of types of food can have (my assumptions are often wrong) and the iMac they have. I put this product in the same sort of category a things like the NIX biosensor, which gives a more accurate assessment of sweat rate for example - I think all these gadgets make you a tad bit smarter, often reveal surprising information, but their relevance and value is highly personal. I do find that I often guess about things and think I know I’m right on, say, liquid consumption on rides, and I can be very wrong - so it’s essentially a reality check and ultimately piece of mind that I am not wildly off on nutrition. The Super Sapiens product is intriguing but not available here in the US, though they do plan to release here. I think Guy Stapleford uses one.