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Lumen Review
Is This Metabolism Tracker Any Good?

Last updated: September 18, 2021

Are you over 50, hoping to learn about the Lumen dating site?

I’m afraid you’ll leave this place disappointed.

But, if you’re curious about the latest Lumen health accessory, I bet we can satisfy your curiosity, so bear with us.

I’ve created this in-depth Lumen review to share the details on how this device can exactly hack your metabolism, what’s the science behind it, what secrets below the hood it can reveal to you, who it’s best for, and other information necessary to figure out whether it’s right for you.

Let’s find out.

What Is Lumen and Who Is It For?

Lumen metabolism trackerLumen is an electronic metabolism tracker developed by a health and wellness company Metaflow LTD to measure your carbs and fat levels simply by using your breath, and find out whether you’re burning carbs or fat to fuel your body.

The metabolic score it provides can help you adjust your lifestyle, customize your diet, optimize your exercise regimen based on your body’s actual needs, and make decisions that will lead you to your desired goals faster.

More details on how the device works a bit later.


It’s designed by Israeli twin sisters Michal and Merav Mor, Ironman triathletes, and it may be helpful not only for professional athletes and trainers, but for anyone who exercises regularly and wants to gain insights on how their body works.

For instance, someone who’s already on a paleo, keto, low-carb, high-protein, or any other diet but hitting a muscle-building or fat-loss plateau may greatly benefit from Lumen’s customizable workout and nutrition plan based on each individual's sleeping and eating habits, and specific goals.

You get those guidelines in addition to daily ketone measurements from your breath so that you always know whether you’re in ketosis, i.e. burning excess fat for energy.

I should also say that this gadget isn’t recommended for anyone under 16, obese people, or those with chronic health conditions like asthma, diabetes, COPD, and similar.


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Pros and Cons

Here is a quick rundown of the pros and cons of the tracker.

  • Sleek design
  • High-quality hardware
  • Portable, handheld, easy-to-charge, and simple-to-use device
  • Provides immediate real-time carbs and fat measurement, helping you customize your training goals and nutrition plan as needed without guesswork
  • Compatible with iOS and Android devices
  • The app offers plenty of resources to encourage sensible health decisions based on your testing score
  • Allows extended fasting
  • The price may be higher (but it’s cheaper and more convenient than traditional RER metabolic testing or regular glucose and ketone blood tests)

How Does this Device Work?

woman using the lumen metabolism tracker

Here’s how the Lumen device works in short and what’s the science behind it.

This metabolic tracker measures the concentration of carbon dioxide (CO2) in your breath through an integrated sensor and flow meter that determines your current body’s fuel - carbs or fat.

Low CO2 levels indicate you’re burning fat, whereas high CO2 levels mean you’re burning carbs for fuel.

Based on the readings, you get personalized recommendations on workouts, sleep, or nutrition,  like what and when you should eat that day, etc.

This at-home tool is said to provide comparable results to the standard clinic measurement of Respiratory Exchange Ratio (RER) method that requires much more time and money to test an individual’s metabolic state. [1]

However, the studies claiming this technology’s scientifically proven to be accurate are internal and haven’t been peer-reviewed.

Still, some other researchers have said their studies show that similar portable devices are mostly precise and can deliver accurate results, so they deserve closer attention and further research. [2] [3] [4]

How Can Lumen Help Improve Your Health?

a bunch of girls using lumen metabolism tracker

Whether you’re already following a specific workout and diet plan or just paving your way to healthy nutrition, Lumen enables you to listen to your body, understand it, and make better, personalized workout and eating decisions based on its analysis.

Lumen aims to help you "hack" your metabolism so that your body can efficiently shift between the use of carbs and fats as fuel, or what's called metabolic flexibility. Some practices and habits that can trigger this are exercising, macronutrient manipulation or changing the amounts of carbs, fats, and protein you consume, and time-restricted eating like intermittent fasting.

“Metabolic flexibility is the main player that extends behind everything -- behind performance, weight loss, longevity, energy. So, we first want our user to achieve healthy metabolism, flexible metabolism, and the outcome of that is a weight-loss improvement.”


-Michal Mor, Lumen Co-Founder

This metabolic flexibility is measured in the app as Lumen flex score which ranges from 0 to  21. According to the founders of Lumen, a good flex score is a sign of improved overall health that can burn fat more effectively, which can also result to the following benefits:

  • Increased energy levels
  • Enhanced physical and mental performance
  • Faster fat burning and lean muscle mass building
  • Better sleep quality
  • Lower risks of metabolic, cardiovascular, and other diseases
  • Improved insulin sensitivity
  • Consistent blood sugar levels
  • Less cravings
  • Stronger immune system

How to Use Lumen Properly

I’ve tried to simplify this process and filter the most relevant information in the instructions below so that you understand the gist.

Step 1: Set-Up

The first step is to download the mobile app on your smartphone, sign up for an account, and connect your device to the app via Bluetooth. (You can log all your data through the app, review the stats, and make adjustments later if you want.)

Then you answer a few questions about your lifestyle, physiology, health goals, etc. such as your activity level, body composition, sleep pattern, and other similar factors to consider.

Step 2: Regular Usage

That's it, you can welcome this pal to your regular daily routine.

The Lumen device is generally easy to use, though it can be tricky to get an accurate reading. Through the app, you will get instructions on how to properly measure your CO2 levels.

It goes like this. You need to inhale until a small colored ring on the screen expands to overlap with the outer gray circle. You should immediately stop once the two rings overlap, or else you have to do it all over again.

After holding your breath for 10 seconds (there will be a timer on the screen), you can then exhale through the device until the ring on the screen disappears. Keep your exhaling slow and steady until a soothing circle on the screen fades. Make sure to avoid blowing out with too much force so you don't end up with inaccurate results.

Once you succeed at breathing through the device two to three times this way, the app gives you a score of 1 to 5, which tells you whether you’re burning fat or carbs for energy.

We could roughly put the test scores into three groups: 

  • 1 or 2 for a fat-burning state
  • 4 or 5 for running on carbs and
  • 3 for a combination of the two energy sources (both carbs and fats)

It's ideal in the morning to have a score of levels 1 or 2, meaning that your body is in a fat-burning mode. A score of 4 or 5 in the morning usually means that your body is still trying to burn what you have eaten the day before.

The Lumen app also suggests that you take a breath measurement before a workout, to make sure you have enough energy to last throughout the session. This is especially helpful for newbies, but if you're already familiar with how your body reacts to meals and exercise, then this device can confirm your current assumptions.

Based on your data, the app typically suggests your daily nutrition plan based on your morning Lumen score in the previous few days, advising you whether to eat low-carb, medium-carb, or high-carb diet that day, including the amount of protein, fat, and carbs.

“We are not trying to recommend a specific food, [like] today eat chicken with rice and some vegetables. That’s not sustainable.”


- Michal Mor, Lumen Co-Founder

After a month of consistent use, you should be able to see your Lumen score which is equivalent to your metabolic flexibility. This is supposed to show how well your body shifts between burning carbs and fats.

General Tips

a man holding a measuring device in his hands

Based on your score from the past mornings, Lumen creates a meal plan for you as mentioned above. I find this very convenient especially when I don't have anything planned out for the day. This is a perfect way to get started with having a healthy and balanced diet every day without starving yourself so much, like some diets do.

To be more specific, it offers a list of suggestions for each of your meals and you can freely customize them to fit your preferences. For example, when I used it to plan for my breakfast, one of the suggestions is a combination of scrambled tofu, black beans, and a green salad.

It also gives other meal suggestions in case you want to substitute scrambled tofu with boiled eggs and a can of tuna which roughly provides the same amount of carbs, fat, and protein. I really loved using this feature because it saves me so much time in choosing the right meals for my diet.

Take note that Lumen encourages some degree of fasting as it advised me to eat not later than 8 o'clock in the evening. That typically results to 12 hours of fasting, though indulging with a scoop of ice cream after dinner from time to time won't necessarily ruin your efforts.

If you want to see the effects of a particular food on your body, you can take measurements one to two hours after eating.

Similarly, to find out how exercise influences your body, you can take measurements before you workout and half an hour after.

Based on those measurements, the app lists down recommendations for exercise routines for your current session. It's cool to see how each exercise stimulates either carbs or fat burning. Before a 30-minute run, I usually get a score of 3 and a 2 after.

The type and intensity of your physical activity also becomes a factor in the meal suggestions it makes. So after a long and intense workout session, it would recommend to increase my carb consumption as well as which type of carbs to include in my diet.

In general, the app suggests low- to medium- carb for most of the days. But if you have a planned physical activity for the day, it will most likely recommend a high-carb meal to provide additional energy to fuel your body.

When taking measurements, make sure you’re relaxed to get the best results, preferably in a sitting position with normalized heart rate, i.e. at least half an hour after any activities.

Where Can You Buy It?

lumen metabolism trackerI always recommend buying any health-related devices and supplements directly from the manufacturer’s official website to make sure you’ll get a genuine product, discounts, warranty, refund or satisfaction guarantee, and other similar benefits.

The same goes for Lumen.

When you purchase this handy gadget and open the box, you’ll also find a charging dock, USB-C charging cable, and a travel case in the package.

Plus, you get access to the Lumen App, which is compatible with iOS and Android smartphones, and premium customer support.

All this comes with a 30-day money-back guarantee, one-year limited warranty, and free US shipping, plus 10% off for ordering two devices.

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Lumen User Reviews

user reviews

After analyzing testimonials shared online by people using Lumen, I’ve noticed high ratings and 85% of positive reviews with plenty of compliments and very few complaints.

Customers have mainly complained about the lack of integration with other fitness services.

Below are the experiences of some satisfied Lumen users, both individuals and fitness trainers who work with clients.

You may take a look at how this pocket-sized gadget has helped them meet their various goals from breaking through the plateau and getting leaner, to learning how to eat healthier, gaining strength, improving endurance, and many more.

“I’ve been using it for over 2 weeks now and I love that it’s easy to use and provides such great feedback on the habits that negatively affects my metabolism. It motivates me to work harder and better!”


- Kim R.

“Seeing the actual numbers helps me perform and recover at my best. I’m 7 weeks in and my recovery times and energy during workouts have improved a ton. I highly recommend Lumen if you want to be more in touch with your metabolism works.”


- Edgar E.


"I really believe in this product because it's putting out data that's tailored to me, for me to be effective with my clients and their workouts. It's injury prevention and smart training at its finest."


- Troy B.

And here’s how Dr. Molly Maloof reviews Lumen's technology:



Does Lumen Help With Weight Loss?

Yes, Lumen does help with healthy weight loss in a way that it guides you to better fat utilization, helping improve your metabolic flexibility, and keeping you motivated to stick to your healthy diet plan.

Can Two People Use the Same Lumen?

No, two people can’t use the same Lumen. I mean, theoretically, they can, but it’s neither convenient nor recommended.

The device is designed for individual use. To get the most out of it, users should download the Lumen Apps to their smartphones, create a personal profile, and do breath measurement consistently throughout each day to get meal plans and other helpful health and exercise tips on the way towards achieving their personal fitness goals.

How Much Does Lumen Cost?

Lumen costs $349, but there’s a limited time offer at the moment so you can get it for $299.

Before you order your device, it’s always better to check the current pricing, discounts, and any available special offers on the official Lumen website

Is Lumen Accurate?

Yes, Lumen is accurate provided that you closely follow the instructions of the Lumen app, as well as the breathing protocol when using the tool.

Is Lumen Safe to Use?

Yes, Lumen is completely safe to use. It’s just a breath analyzer that helps track your metabolism to achieve your desired goals faster.

Is Lumen Considered A Medical Device?

No, Lumen is not considered a medical advice. It is a wellness product that helps you measure, track, analyze, and hack your metabolism. Since it's not a medical advice, it does not provide diagnosis, treatment, or prevention to certain diseases. The recommendations are based on the inputs like carbon dioxide levels and physical activity, and should not be considered as medical advice. It's best to consult with your physician if you have any questions about your health.

Should You Buy Lumen?

Hopefully, you'll be able to answer this question for yourself after reading this review.

I’d certainly recommend Lumen as a handy companion to anyone who’s serious about achieving their fitness, diet, and health goals because its valuable readings and guidelines can make you aware of what workout or eating habits may undermine your weight and other goals, suggesting effective ways to overcome those obstacles.

Check it out to see if it lives up to your expectations. Then, let us know what you think.

Our #1 Recommendation

Lumen tracker


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Is This Metabolism Tracker Any Good?

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