Product Description:

KNOW IF YOU’RE BURNING FAT OR CARBS—IN SECONDS: Track your metabolism in real-time with a single breath using the Lumen Metabolism Tracker Device. Instantly see how your body responds to food, sleep, and workouts—and use that feedback to lose weight, boost energy, and become metabolically flexible. No more guessing—just daily, personalized data for smarter health decisions.
BUILT AROUND YOU, DESIGNED FOR RESULTS: Lumen is for anyone stuck in a weight loss rut, feeling drained, or just wanting to understand their body better. Whether you’re juggling work, hormones, or training goals, Lumen’s data helps you personalize your macros, improve performance, and support fat burn, so you’re synced to your body’s rhythms and can achieve your goals in a way that fits real life.
CLINICALLY VALIDATED & EXPERT BACKED: Lumen is grounded in science and validated in peer-reviewed studies. Used in health clinics, gyms, and trusted by professionals to help people improve metabolic health through real-time breath analysis and personalized lifestyle guidance. With one app, monitor progress, optimize results, and unlock the data your body’s been trying to tell you all along.
SMART TOOLS TO TRACK WHAT REALLY MATTERS: Use personalized nutrition plans, AI-powered meal suggestions, and a fasting tracker to pinpoint your fasting sweet spot and avoid muscle breakdown. Turn carbs into fuel to reach peak fat burn and learn how to eat in sync with your hormones. With 50+ integrations across your favorite apps, track progress and personalize your journey with deeper insights.
WHAT’S IN THE BOX: Lumen device, USB-C charging dock and cable, travel case, and access to the Lumen app. Your 12-month subscription unlocks all premium features, personalized coaching, and access to our exclusive in-app community for real-time support and lasting results. Battery life up to 10 days. iOS and Android compatible. One-year limited warranty. Smartphone not included.

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Products Reviews:

Reviewer: MBan
Rating: 5.0 out of 5 stars
Title: Lumen Breath Analyzer
Review: I am an experienced dieter, track everything: weight, movement, macros, fat percentage, sleep, hrv, vo2… you name it, I track it. This is my second Lumen. I got the first one when they first came out several years ago and it still works. I was on keto then. Very anti carb, and I didn’t really like the Lumen approach. I thought I could diet my way out of a metabolic issue. Well when you keep losing and gaining the same 40 lbs, you might be wrong! The second time using Lumen, I lift weights, carb cycle with high protein, low sugar. Both my Lumens are consistent and accurate to each other. They measure co2 in your exhale to show whether you are in carb burn or fat burn. Being on keto for 10 plus years, I was fat adapted. But using fat for energy and losing fat off your body are two different things. With Lumen this time 18 lbs down in 18 weeks and gained 5 lbs of muscle. My metabolism is much better and my bmr is increasing while losing weight. I’m down 4% body fat, far more than I could lose before.I can cycle in and out of fat burn using Lumen to test whether my diet is supporting my workouts and recovery. Too much carb and I don’t go into fat burn even though I stay in a calorie deficit and lose weight: I don’t lose fat, confirmed by my body fat scale. I have used Lumen to push through a plateau when my macros were off.It is easy to use and the app has a huge amount of information to help you reach your goals. It pairs with Apple Health and Activity so you can see all your metrics there. Yes it is pricey and requires a subscription. I was able to stop using it for a year and then restarted with my old device. It is worth trying their approach if you are struggling with your current diet. I feel and look healthier with a lower body fat percentage. Can’t ask for much more than that!
Reviewer: Cisco
Rating: 4.0 out of 5 stars
Title: Insightful fascinating metabolism device!
Review: The Lumen Metabolism Tracker Device is a fascinating piece of tech for anyone serious about understanding their body’s fuel usage. This device measures your real-time fat and carb burn with just a breath, which is pretty revolutionary for personalized nutrition.I find it incredibly motivating to see exactly how my body is responding to different foods and workouts, offering immediate feedback a scale can’t provide. What’s more, using the device has even helped improve my breathing and lung capacity, almost like an incentive spirometer. It’s a great lung exercise and an unexpected positive side effect! The device itself is intuitive, and the app has been incredibly stable, never crashing on me.The subscription (this one comes with a three-month plan) unlocks all the personalized features and long-term tracking, which is essential for seeing trends and making informed decisions about your diet and exercise. While I’m still figuring out if this is a long-term fit for my keto lifestyle, the real-time data is invaluable. My main wish is for a wider and more accurate food logging database, as I often can’t find what I eat, requiring me to use another app for that. An AI image scan for food logging would be a fantastic addition.
Reviewer: Luce
Rating: 2.0 out of 5 stars
Title: Not accurate
Review: Ok, so I wanted to really test this guy out and give it a solid review. I’m someone who’s done keto off and on for a while and I was hoping that this could help me determine whether I was in a fat burning (keto) or carb burning (regular) state when cycling in and out of keto.I downloaded the app, which is easy enough and fired up the lumen. It apparently needs to get to the right temperature. Then it guides you through some set up and to your first breath recording. You have to inhale through the lumen just enough to get the ball to the center of the ring, but not too much or too little. This finesse took me a few tries, then you have to hold your breath for 10 seconds as it counts down, and blow into the lumen for a few seconds, also finessing the ball into the ring on the app. Some recordings didn’t work, or I had to redo them because I didn’t do it well enough, but overall, the experience was not too bad.It rates from 1-5, fat burning or carb burning, with a 3 being “50% fat burning, 50% carb burning” according to the app. As far as I’m aware, there’s no such thing as 50% carb or fat burning, but I put that logic aside and just jumped along for the ride.Now, for the results: I was strict keto for three weeks prior to this device arriving, which is plenty of time to get me into a fat burning state. The first morning it said I was 100% fat burning, then the next day said I was 75% fat burning, day 3 was 100% fat again, then day 4 was 100% carb, day 5 was 50/50.Then I went off keto and had an indulging day of sugar. The next morning it said I was 75% fat burning.If all of that makes no sense to you, you’re right. I was eating keto, under 20 grams of carbs and getting readings that were all over the place, when those should’ve said 100% fat burning for all 5 days. I measured in the morning before any food was consumed. Then I went to a more standard American diet, and it said that I was still in fat burn, when I should’ve been in 100% carb burn.I’m going to keep testing this out, but so far the results don’t seem to be based in any degree of accuracy. Also, the app doesn’t actually want you to follow a keto diet. After putting in all my information, the app wanted me to do a moderate carb diet of around 100g/day, which would be low for the standard American, but is no where near keto.I’m keto for the cognitive benefits as well as the physical benefits, but I also love to cycle in and out every now and then.My ultimate goal is to be able to cycle with ease and I was hoping this device would help me gage where I was at. Oh well, back to the urine strips.