FeaturedNutritionReview
The early morning light streams through your kitchen window as you prepare for the day ahead. Your Lumen device sits on the counter, ready to guide you toward better health. This isn’t just another fitness gadget—it’s a scientifically validated tool designed to decode your metabolism in real time. Whether on a weight-loss journey or an endurance athlete, Lumen gives you actionable insights that empower your choices, helping you burn fat, optimize energy, and prove it works.
This review dives into the strengths and weaknesses of Lumen, explaining how it works, what sets it apart, and who it’s best suited for so you can decide if it’s the right tool for your journey.
The Lumen ecosystem offers personalized nutritional advice, follows a keto-style approach, and syncs with Garmin and Apple Watches. It’s often on sale, and my code, THE5KRUNNER, is automatically updated to the ongoing promotional rate, often saving you over $100. For instance, using the code the5krunner during Black Friday can get you $130 off and a 50% discount.
Lumen review Summary
90%
Lumen Verdict: The only way to prove to yourself your diet and exercise combine to burn fat.
Key Factors to Consider: Is Lumen Right for You?
Lumen excels in three main areas crucial for its target audience of dieters and athletes:
- Metabolic Tracking: The device measures carbon dioxide in your breath to estimate whether you’re burning fat or carbohydrates, giving a personalized metabolic score (1-5). This is particularly valuable for dieters and athletes aiming to optimize energy usage from fat rather than carbs.
- Ease of Use: The device is portable and easy to use. Paired with the Lumen app, it guides you through daily readings and provides thorough and tailored recommendations for workouts and meals.
- Personalization: It integrates with Garmin, Android and Apple Health ecosystems for comprehensive fitness tracking, tailoring advice to your unique goals and lifestyle.
What Makes Lumen Unique?
Unlike traditional apps that rely on estimated calorie burn from heart rate data, Lumen uses direct CO2 analysis for metabolic tracking, offering unparalleled precision. This level of insight is typically reserved for lab-grade equipment but is now accessible at home.
Lumen Competitors and Ideal Users: Who Is It Best For?
While Lumen is in a niche of its own, alternatives like Breezing and FoodMarble cater to similar health-conscious users but lack Lumen’s scientifically validated fat-burning approach. Lumen is ideal for:
- Anyone seeking dietary guidance and a fact-driven approach to prove weight loss comes from fat
- Individuals on keto or low-carb diets.
- Endurance athletes aim to maximise fat-burning abilities for endurance performance.
Pros
- Scientifically backed insights into fat and carb-burning.
- Syncs with Garmin, Android and Apple Watch ecosystems.
- Motivational for users by providing actionable data.
Cons
- Readings can vary slightly depending on breath consistency.
- Optional subscription for full functionality
- CO2-only sensors are known to be less reliable for users in deep ketosis.
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Lumen History: Has It Changed Over Time?
Lumen has continually refined its app interface, introducing features like food logging and expanded integrations with fitness platforms. However, the hardware remains consistent, with no major updates since its release.
Lumen’s Design: Practicality Meets Innovation
The Lumen inhaler features a sleek, minimalist design, a hygiene cap, and a long-lasting rechargeable battery. The decision to rely solely on CO2 measurements, excluding oxygen sensors, limits its scientific rigour but enhances portability and cost-effectiveness, still delivering scientifically validated results.
Lumen Performance: Key Metrics and Facts
- Battery Life: Up to 14 days on a single charge.
- Weight: 75g for the device.
- Accuracy: Peer-reviewed studies claim 80-90% accuracy in estimating metabolic states compared to medical-grade tools.
Insights from 3 Years of Lumen Use
While not replacing lab-based respiratory exchange ratio (RER) tools, Lumen offers an affordable alternative for practical, everyday use. Its approach aligns with established metabolic science, albeit with some limitations.
Lumen Review: What you need to know beyond the manufacturer claims
Through daily use over many months, my partner and I found that a consistent breath technique is critical for reliable readings. For instance, I achieved better results by following a precise routine: exhale fully, inhale steadily, and avoid holding air in my mouth. Small adjustments like these enhanced the device’s utility and accuracy. The app includes a visual tool to help you get your breathing rate right when taking readings.
How Lumen Works: Scientific Evidence and Personal Tests
Lumen has peer-reviewed science to support the efficacy of its product. See www.i-jmr.org
Lumen also claims:
Lumen’s technology has been scientifically proven to accurately measure metabolic fuel usage when compared to the gold standard (RER) for measuring metabolism in multiple validation studies.
Lumen hasthis page, which cites studies by Lorenz and Mor & Mor. Both studies involve Lumen employees, and one is peer-reviewed. Having employees involved in the research is not unusual!
I pointed out to Lumen that their device does not contain an O2 sensor, which is typical of medical-grade RER devices. They replied,
Measuring the CO2 concentration in one’s exhalation can be used as an indicator to one’s metabolic fuel dynamics according to the following principles:
- Cells that use carbs as fuel produce more CO2 (relative to the consumption of oxygen) compared to when they use fat.
- In a rested condition, the oxygen consumed does not change dramatically, so a subject’s Respiratory Quotient would be mostly represented by changes in CO2 production.
- The CO2 concentration in mix venous blood correlates to the metabolic fuel dynamic.
- The breath-holding technique enables us to determine the CO2 concentration in mix venous blood.
In order to provide fully clear results with Lumen it is therefore important that one is entirely at rest when taking a measurement.
Getting an RER test in a medical lab is tricky. Handily, I have a ketone + glucose blood reader from my look at HVMN a while back. So I used that 🙂
My starting point was that blood ketone levels above 3mM usually indicate ketosis. While there are reasons why a breath test might yield different results from blood or urine ketone tests, I anticipated a general agreement. Here’s what I discovered:
I conducted four tests, and Lumen reported a fat-burning score of 2/5 or 1/5 each time. Concurrently, my blood ketones were above 3.0 on three occasions and below 3.0 on the 4th. For a non-invasive test, I found this to be ‘reasonable’ but not necessarily scientifically conclusive. On the three occasions with higher fat-burning levels, they occurred after long, easy morning workouts (without eating late at night), which was expected.
However, fasting for 14+ hours didn’t consistently result in Lumen reporting a fat-burning state for me, and I did NOT anticipate that. This discrepancy might occur because a deep state of ketosis can produce more CO2, potentially leading to a false positive for carb burning.
Lumen FAQ: Your Questions Answered
Q: Is Lumen Accurate?
A: After nearly two years of use, I would say Lumen is accurate for all of us in most normal situations. Lumen publishes scientific papers that claim accuracy in specific circumstances. My own limited and unscientific testing found occasions where Lumen’s results matched results on ketone strips as well as my expected results. Some results didn’t match.
Q: What is a good lumen flex score?
A: 21 is a perfect score, and anything over 15 is good. Average scores range upwards from 7.
Q: Does Lumen Work?
A: Yes. Lumen certainly senses carbon dioxide and infers carb/fat consumption. It’s not just making the number up. However, I can’t say from my experience if it has medical-grade results.
Q: Can I use Lumen without a subscription?
A: Yes.
Q: Does Lumen Work with Apple Watch?
A: Yes, kind of. Lumen works primarily with a smartphone app. However, Apple and Garmin apps offer extra (free) features on your favourite watch.
Q: How good is Lumen?
A: I’d say it’s good. Lumen has put together a good package of inhalers and software with some cool insights for athletes and those on diets.
Q: What is the Lumen metabolism Tracker?
A: The Lumen device is like an inhaler and measures the flow of air and its CO2 content. It infers your fat/carb usage and further assumes you are rested.
Q: What are the alternatives to the Lumen metabolism tracker?
A: One alternative to Lumen is the Breezing Starter Kit. I’ve not used it, and it has highly indifferent consumer reviews. Trustpilot has great review feedback on Lumen, which, of course, doesn’t prove it’s scientifically accurate, but it does show that users are generally pleased with the product. Foodmarble is another alternative that analyses the hydrogen content of your breath. Lumen has no consumer-grade competitors to measure fat burn from breath signatures.
Q: What were previous generation Lumen devices?
A: Lumen has only had one version. This is the original version; I know of no planned replacement or upgrade.
Q: Can I share Lumen?
A: You can but think about the hygiene aspects. Also, repeatedly pairing it between two separate smartphone apps is time-consuming. Consider the DUO option, which further discounts a second Lumen.
Lumen Pricing, Discounts, and Availability
Get the Lumen device for $179 (regularly $299) this Black Friday using code THE5KRUNNER. Subscriptions start at $19/month for advanced features. Visit Lumen’s website to learn more and enjoy these exclusive deals – the same deal is applied to your local currency.
The Lumen device is frequently discounted below the rrp/MSRP of $299/£299/Eu299. An optional monthly subscription at $19/£19/Eu19 accesses nutritional guidance and other app features.
Lumen Review Summary: Is It Worth It?
Lumen isn’t just a gadget—it’s a transformative tool for anyone serious about understanding and optimizing their metabolism. Whether burning fat to lose weight or boosting endurance for your next marathon, Lumen offers scientifically validated insights that empower your choices. While the subscription adds ongoing costs, its precision and motivation make it a worthwhile investment. Prove to yourself that your efforts are paying off—Lumen delivers the evidence you’ve been waiting for.
Use code THE5KRUNNER for discounts, and join a large community of users who are finding success with Lumen.
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