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Sharing my full review on the Lumen metabolism tracker and if it’s worth it. This post is not sponsored, but if you’re interested in trying Lumen, you can use my affiliate link and code FITNESSISTA for an extra 10% off!
One of the most common themes I hear in the fitness world (online and with my 1:1 virtual and in-person clients) is the of concept metabolism. It changes and shifts over time, and while it can obviously work in your favor, it can also be tricky to hack and understand.
What the heck is your metabolism? Your body’s metabolism is the process by which it converts food into energy, either to be used immediately or stored for later use. Metabolism can affect so many different factors: weight loss/maintenance/gain, sleep, immune system, fitness performance, energy levels, longevity, and blood sugar stability.
Metabolic flexibility is the key insight into how well your metabolism is functioning. You want your body to be able to easy switch between using carbs and fats as a fuel source, depending on what’s available. Our metabolic flexibility can be improved by our diet (specifically through macro manipulation), workouts, and time in between meals.
Knowing how your metabolism is functioning can be a key player in designing your personalized diet plan and workout routine, and this is where Lumen comes in. Lumen is the first handheld metabolism tracker and I’ve been using it now for a little over a month! I’m so pumped to share my insights with you -I’ve learned so much!!! – and talk about whether I think this little gadget is worth implementing in your routine.
Lumen Metabolism Tracker Review
The Lumen Metabolism Tracker was launched in 2020, and the founders are twin sisters Merav and Michal, who are both Ironman winners (!!!) and PhDs in physiology. They created this metabolism tracker as an affordable and convenient way to test metabolic function, and tweak nutrition and lifestyle suggestions based on this data.
You breathe into the Lumen (more details on how to do this below) and the CO2 levels in our breath helps Lumen to determine our Respiratory Exchange Ratio (RER). It rates this on a scale of 1-5 (from 1 to 5; 1 is mostly fat and 5 is mostly carbs) and this number is based on whether we’re predominantly burning carbs or fat in that moment. Lumen suggests a macro split for the day, depending on your RER, your workout for the day (you can input each day’s workout into the app), sleep, and previous day’s data.
The Lumen was designed for those who want to make sustainable healthy changes in their routine, or are mystified as to why their progress and results have stalled. It gives you personalized data and a solid plan for achieving your goal, whether it’s sports performance, body recomposition, weight gain, weight loss, or metabolic health.
The fact that Lumen is SO portable and convenient is truly incredible. In the past, I’d thought about finding a way to test my Respiratory Exchange Ratio, but there wasn’t an easy or convenient way to do this. Lumen has been validated to meet the gold standard for metabolic measurement in this study.
If you decide to order, just head to the website and you can pick a subscription package:
When the box arrives, you’ll find your Lumen, instructors for setup, a charging dock, and a travel case.
Lumen Metabolism Tracker Features
Lumen has an “on” button in the middle that illuminates when you press it. It only stays on for a couple of minutes – just enough time for you to complete your breaths- and the battery lasts an extremely long time. I only need to charge it about once per week.
The app is beautiful and very easy to navigate. Within the app, you can view your nutrition plan for the day, access multiple articles and resources, chat with support, and view previous data. The app also syncs with your Apple Watch and/or Garmin. They also have an app FOR your Apple Watch and I had no idea. Adding this ASAP.
Customized nutrition plan
At the top of the app, you’ll see your nutrition plan for that day. It gives you specific macros, but also just gives you carb servings in yellow. A carb serving is about 15g of carbs, or one cupped hand of carbs. (Starchy vegetables, fruit, bread, rice, grains, etc.) If you don’t want to track all of your macros, you can solely track carb intake and see results using their plan. I love this method because the portion size model is similar to what we do at Precision Nutrition. I also don’t think it’s realistic or sustainable to track/weight/measure ALL food for life, so I think they’re really setting up users for longterm success.
Within the app, you can also see your Flex score, which is created after they have 4-8 weeks of data. Your flex score indicates your metabolic flexibility (I think 21 is the max), and you can see how your scores improve and change over over time.
I’m a huge fan of assessing habits, and this app gives you real-time insight into how your habits affect your metabolism, plus tips on what you can do to improve.
How To Use The Lumen Metabolism Tracker
When you first receive your Lumen, simply plug in the USD charging dock and attach the Lumen to charge. The first charge took maybe 20 minutes. While the Lumen is changing, you can install the app on your phone, which will sync to Lumen using Bluetooth.
Once it’s charged you can input your basic data, including age, weight, sample weekly workout schedule (you can adjust these each day but it’s nice to have an idea already in there), activity level, how long you typically fast each night, etc. From here, you can take your first breath reading!
First breath reading
It helps to watch this tutorial before taking your first reading. You’ll exhale a tiny bit out through your nose, then inhale deeply into the Lumen. Remove it from your lips, and keep your lips closed as you hold your breath. The Lumen will count down and tell you when to exhale. The inhales and exhales are deep and slow – like a long exaggerated deep breath. After having Rona, it felt so so good to use my lungs in this capacity.
After you exhale into the Lumen, it will either indicate your reading or ask you to do one more breath. Next, you’ll receive your score on a scale of 1-5 (1 is burning mostly fats and 5 is burning mostly carbs). The *goal* is to blow a 1 or 2 in the morning for your first reading, indicating that your body has burned through dinner and switched to fat burning mode.
Remaining breath readings
Lumen recommends breath readings when you first wake up, before exercise (30 minutes), after exercise (30 minutes), before eating, after eating (1-2 hours to see a shirt), after fasting, and before sleeping. This can sound like a lot of readings, and it is. I recommend just doing your morning breath and before sleep breath to start, and then adding on from there.
Obviously, the more times you do it, the more data you’ll have, but it can be overwhelming to go from zero to 8+ readings per day. I always do the morning breath, before bed, and try to remember to check it before my workout and afterwards. When you check it before and after your workout, it can tell you whether you should fuel up with carbs (depending on the length and intensity of the workout you’re about to do, which you input into the app), and it can also tell you if you have shifted into fat burn following the workout.
Using your nutrition plan and data
On your homepage in the Lumen App, you’ll see your nutrition plan for the day. From here, I recommend just keeping a tally in the notes app of your phone with carb servings for the day. You may be surprised by how many carbs they recommend, especially if you’re used to a low-carb or Keto diet.
Here’s the thing: your body needs carbs, and it LIKES them. Trust the process! In the Facebook group, there are incredible stories about people who used to be low-carb, switched to Lumen, and have seen significant fitness gains or weight loss.
Your data will give you insight into your habits and how they affect your score. A high-carb meal or a lot of alcohol before bed can lead to a higher morning score, as can late-night meals, poor sleep, increased stress, overtraining. High cortisol leads to a higher score and inhibits the body’s ability to burn fat. (Genetics and age also play a part in metabolic function.) You can see how your diet and lifestyle are affecting your score and hack your metabolism by making tweaks to your routine.
Is The Lumen Metabolism Tracker Worth It?
I’m a huge fan of this device, and as someone who has tried multiple fitness gadgets, it’s right up there with the Oura ring for most valuable health/fitness device. I’ve only been using it for a month, but have already learned so much about my body and how it processes and uses energy throughout the day.
Some of my favorite things about it:
– I LOVE that it takes menstrual cycle into account, and notates where you are in your cycle within the app. It will give specific tips based on where you are in your cycle, like needing more fiber during post-ovulation to combat lower leptin levels.
– Support. The support team is incredible and very responsive. I had a couple of questions initially and they responded right away. They also offer a free 30-minute intro call with an expert to help you get set up or answer any questions.
– Sustainable individualized nutrition plan and NO extremes. I feel like this nutrition plan is the real deal. The macros I received were right in line with the macros I’d calculated for myself, with carb cycling based on my workout routine and boost days (which are like double the amount of carbs). I’m absolutely loving it so far and highly, highly recommend it. It’s a helpful tool if you want to track your metabolism and have any health or fitness-related goals.
If you’re interested in checking it out, click here and use the code FITNESSISTA for an extra 10% off.
Please let me know if you have any questions in the comments section!
Are you a fan or fitness and healthy gadgets? What’s your favorite one??