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Lumen Review

Lumen Review

Posted by Jaime Purinton on 18th Nov 2022

The Lumen device kept showing up in my online feeds, and I wanted to find out what it was all about. So, what better way to learn than to commit to using it for three months for a review? And that is just what I did. For three months, I meticulously blew into the Lumen device every morning, every meal, and every workout. I tracked my food, macros, and workouts, and veraciously ate up any information I could learn from Lumen about my unique body and metabolic health. I was on a mission to learn how Lumen could help show me where my metabolic health lies and how to make it healthier. 

So, what is a Lumen? 

The Lumen device is the "world's first hand-held, portable device to measure metabolism accurately. Once available only to top athletes, in hospitals and clinics, metabolic testing is now available to everyone. Lumen measures your metabolism in a single breath and can help you lose weight and optimize your workouts. From metabolic tracking to personalized nutrition plans, Lumen is an effortless metabolic tracking and wellness coach all in the palm of your hand". 

How does it work? 

The Lumen device has a C02 sensor and flow meter that measure the C02 in your breath when blown into. This measurement is interpreted to understand if your body is burning carbs or burning fat. This measurement is relayed to you as a number between one through five, one meaning you are burning fats and five meaning you are burning carbs. Over time, these measurements create a comprehensive evaluation of your metabolism and determine your metabolic flexibility, i.e., the ability of your body to switch between burning carbs and burning fat. These get translated into an overall "flex score" that goes up or down based on what your metabolism is doing. Based on the measurements and your predetermined goal (lose weight, increase performance etc.) Lumen provides a daily macro guide that will help you achieve your goals. 

How is this important for health? 

The benefits of metabolic flexibility include more effortless weight loss, better sleep, better workout performance, building lean muscle mass, weight maintenance, and more energy. It also helps increase insulin sensitivity and burn more fat for energy, all of which I am happy to receive!

What are the pros and challenges?


Amazing Tool: The lumen device is easy to use and works well with the app. I had virtually no issues over the three months I used it.

Awareness: It helped me to understand how my metabolism was affected by sleep quality, physical activity, nutrition, and stress. It opened my eyes to certain habits I had adopted that were wreaking havoc on my metabolism (hello, anxiety).

In-App Meal Tracker: The app includes a meal tracker that allows scanning labels for automatic entry (now a paid feature for the My Fitness Pal App. While most meals are already available, it makes it easy when you encounter one that has not been uploaded into the app. The app also has healthy recipes that are easy to make and delicious. These recipes include carbs, protein, fat macros, and substitute ingredients to make it even easier.

Persuaded Healthier Choices: Once I started to learn what affected my metabolism negatively, I made healthier choices. That awareness and knowledge were worth their weight in gold.

Facebook Group: Joining the Lumen Facebook group helped me understand the device's nuances and our individual metabolism. There are "Lumen experts" in the group that are happy to answer questions and share resources.

Lumen in-app help: Lumen's customer service is 5 out of 5 stars. Any questions I had, they responded thoroughly and promptly. When I reached out about my concerns about hitting my macro goals, they worked with me to modify them to something I could achieve and stay within my goals.


Tracking: I was already doing this, so there wasn't a change for me, but if you're not used to tracking everything you eat, it can feel like a ton of work. The benefit of tracking food is building a picture to understand better how food affects you. This, combined with the data from Lumen, helps dial in the foods that are good for your unique metabolism. The tracking capabilities in the app are a little limited. It does not save previously entered meals for different mealtimes. For example, if you save a meal for dinner, you will need to enter it all again if you need to save the leftovers you eat for lunch the next day.  

Hard Macros: One caveat here, I am a vegan so getting the high amounts of protein Lumen recommended was tough (one can only eat so much tofu). I also saw the same sentiment from meat eaters, so just keep that in mind when starting to use Lumen. On "boost” days, aka high carbs days, I also had a hard time eating all the carbs recommended but eventually got the hang of it.

Connectivity: The Lumen device only works if connected to wi-fi. I found that out on a backpacking trip and was unable to use the device for a few days, resulting in a lower flex score when I returned from my trip.

Learning Curve: There is quite a bit of a learning curve at first which can be frustrating. There is a lot to learn about how the device works, what causes different numbers when blown, our metabolisms and what affects them (food, stress, sleep, exercise). But learning all of this, in the end, has benefited me as I now have a deeper understanding of my health and body. I recommend going into your Lumen journey with an open mind, patience, and a deep commitment to doing all that needs to be done for it to be a helpful tool and help to improve your health.

Overall, the Lumen is a great tool. It is not a miracle device. You still need to do the work, follow the macros, and spend time tracking all your food. For those that follow this, it works very well. Something to note: Lumen is not recommended for anyone with Diabetes or on a keto diet. For more information, visit Lumen's website at