Join the hundreds of thousands finally seeing real results
Reach your weight loss goals
Know what to eat and when to fast for your best body, without the guesswork.
Smash through your PRs, PBs, and workouts
Fuel your body with precision and see the gains to match.
Manage your menopause with confidence
Lumen helps you navigate weight changes, energy dips, and cravings with personalized insights.
Future proof your health
Feel stronger, live longer. Outperform your potential with the world's first device that measures metabolism in 20 seconds.
“Lumen has been a huge help to me on my journey to metabolic flexibility. I use a continuous glucose monitor at times to keep my blood glucose levels in a healthy range, but at times I tend to rely too much on a very low carbohydrate diet to do so.
By using Lumen too, I can ensure that my low glucose levels won’t be at the expense of metabolic inflexibility. The staff at Lumen has been extraordinarily helpful — and always promptly — with any issues I had using the Lumen, from app issues to nutrition, to billing and membership.”
"I'm hitting my weight loss goals and enjoying food again thanks to Lumen. I was skeptical, but the information this device provides combined with the nutrition plan has yielded amazing lasting results:
Lower BMI, higher hemoglobin, lower blood pressure, lower resting heart rate, better body composition, and all the carbs I thought I couldn't enjoy!"
"I gained pandemic weight and then menopause came. I’ve always been slim but then I was gaining weight with difficulty losing it. Nothing was helping even a pretty good exercise regime. This device arrived one month ago and I’ve already lost 7lbs.
It’s kind of like a miracle. The real time carb/protein/fats tracker really helps me adjust during the day. Gone is the rollercoaster ride of energy and cravings! Amazing, amazing. Thank you!"
"I like how Lumen is helping me to learn my body’s signals. I also appreciate that the app tailors my macros throughout the day based on my activity.
I used to meal prep and eat the same thing for a week, but some days my activity and stress levels are different than others, so it makes perfect sense that my body may need fueled differently each day too."
"Before purchasing lumen, I did as much research as possible and looked at dozens of reviews. I was still surprised when I download the app and began using lumen, as to how much collateral there was.
Not only does Lumen track your metabolism, the tracks of sleep, exercise, and has a built-in food log with a very good barcode, reader and database of foods. It’s very clear that they have done the research on what people want! Worth every penny so I bought two for my wife and I!"
"I’ve been eating healthy, following my macros and working out regularly (weight training mostly) for a couple of years now. I even went to a nutritionist and went through some evaluations to see what I could do differently. I still felt like I was at a plateau and Lumen appears to be the missing link.
I have learned new foods to incorporate into my clean eating and have learned so much overall about my body and metabolism. I feel better than I already did, my sleep has improved and I’ve lost a few pounds in the first few weeks even though that wasn’t a goal of mine."
"My friend who is in her 60's has had great success in getting to a healthy weight. I was surprised to learn that she really wasn’t exercising because of a bad leg injury she had sustained, but more surprised to learn that Lumen was how she was managing to lose weight!
I was motivated by her results so I bought one. I’ve been using Lumen faithfully day, and night and have lost 6 lbs in 6 weeks thus far. It took some time to learn how to raise my Flex Score, but I’ve been managing to do it little by little. After all, it’s not a race! Slow and steady for me!"
״For me this has been a very enlightening experience. Going through all the weight loss and nutrition information that is available on the internet can be very daunting and confusing. But so many of the techniques I had read about before are integrated into the lumen experience.
But without lumen I never could have figured out how to use the techniques. I’m talking about intermittent fasting, carb cycling, tracking my macros, etc. I had done all of these things before with limited gains. But it’s hard to stay on track when you don’t have any feedback as to the changes that are taking place. With lumen you can see what impact your actions are having on your metabolism. This kind of biofeedback is immensely motivating and useful.״
Trusted by doctors and experts
I lost 4lb the first week and 2lb the second...but more importantly, I was no longer sleeping badly or tempted to have a nap at 4pm.
You could hire an expensive coach or you could hack your health with Lumen.
Breathe into it and the Lumen will tell you how well you're burning fat, and how to eat healthier.
This Smart Gadget Helps You Hack Your Metabolism And Lose Weight.
What once took over an hour to measure, and a team of nutritionists and scientists to analyze, can now be done in less than three minutes.
I lost 50lbs in seven months by changing one thing about my routine - Lumen
As a nurse and a woman who has struggled with weight loss…trying Lumen was eye-opening and validating.
To get a metabolic reading in the past, you had to go to a lab. Now you can keep it in your purse or gym bag.
Cleverly, all you have to do is breathe into the handheld device (which is small enough to fit in even the smallest handbags).
Choose a plan. Save big on annual bundles
Or go with a basic bundle
The Lumen device and app membership come bundled together to give you a full-spectrum view of your health.
Choose from four flexible membership plans to support your goals and fit your budget.
Accessories. Little extras that make a big difference.
Protect your Lumen with a durable shell and clip-on hook for easy, everyday carry
Keep an extra charger at work for easy measurements on the go.
Keep an extra charger at work for easy measurements on the go.
Keep your Lumen safe while on the go.
Keep your Lumen safe while on the go.
Protect your device with a magnetic cap.
Protect your device with a magnetic cap.
Extra charger, soft case, and cap to keep you on track
Extra charger, soft case, and cap to keep you on track
Add-ons. Enhance your journey.
Expertise, guidance, and motivation - all in one place.
Message our registered dietitians in real time. Ask questions, get meal guidance, and stay motivated with expert support—all from your pocket.
Lumen’s unique technology has been validated to match the gold standard for metabolic measurement, giving you access to lab-level insights from your home.
The advanced lithium-ion polymer battery provides rapid charging, and lasts for ~10 days of use.
Compact, but powerful. Lumen fits in your hand, pocket, or handbag - ensuring effortless measurements anytime, anywhere.
Form meets function with Lumen’s minimalist aesthetic and ergonomic design, made with high-quality materials to a top-tier standard.
Know if your body is burning fats or carbs and get daily guidance on how to reach your health goals.
Receive a personalized nutrition plan each morning based on your unique metabolic data. Your macros and meal suggestions adapt daily depending on whether you're burning fat or carbs
Get AI-powered meal suggestions that align with your daily macros. Easily log meals via photo or voice for real-time feedback and accountability.
Understand how your food, sleep, workouts, and stress impact your metabolism. Get lifestyle tips and insights that help you make smarter daily decisions.
Access expert guidance and community support to reach your goals. Lumen provides science-backed coaching and educational tools to help you stay on track.
* certain app features require an active membership
The Lumen device uses a CO2 sensor and flow meter to determine the carbon dioxide concentration in your breath, which indicates whether your body is burning fat or carbs. This measurement builds a daily nutritional plan.
4.02in X 1.63in X 1.31in
0.21 pounds / 95g / 3.35 oz
The advanced Poly Ion battery provides rapid charging and assures ongoing usage, even in long business or fun trips, without the need to charge the device more than once every 2 weeks.
Metabolic flexibility refers to how efficiently your mitochondria switch from burning carbs or fats for fuel, depending on their availability and your body’s needs.
Being metabolically flexible can be important for disease prevention and helps with managing weight, improved insulin sensitivity, higher energy levels, better sleep, and even longevity.
When your mitochondria use carbs as fuel, they release more CO₂ into your blood, and when they burn fat, they release less CO₂.
Lumen analyzes the %CO₂ in your breath and determines if you are using mostly fat or carbs for fuel based on the CO₂ concentration.
Lumen has been validated to match the gold standard for metabolic measurement with an at-home, handheld device.
Lumen’s technology is validated by multiple peer-reviewed scientific studies and is proven to measure metabolism as accurately as the gold-standard metabolic cart. Read the peer-reviewed paper.
After adding your Lumen to the cart, select “HSA|FSA” as your checkout option, currently available only for annual or annual Duo memberships.
At checkout, Flex will prompt you to fill in a short health questionnaire to confirm your eligibility to pay with your HSA/FSA.
From there, enter your HSA/FSA card details and complete your checkout as usual.
If you don’t have an HSA/FSA card, you can complete the checkout with a regular credit or debit card, and Flex will provide you with an itemized receipt to submit for reimbursement.
Yes, the Lumen device and app work together. The Lumen device measures your metabolism through your breath in real-time and the app provides personalized insights and lifestyle guidance based on those measurements.
Yes, you can cancel your membership at any time. Cancellations will take effect on the next billing cycle.
Your membership will start when you activate your account after receiving your Lumen device, or 10 days after your purchase, whichever is earlier.
Yes, for Lumen devices purchased starting July 30th, 2023, after the cancellation comes into effect you’ll still be able to take unlimited metabolic measurements. However, you won’t have access to the Lumen membership experience, including granular results, measurement history, personalized insights and tailored guidance.
Lumen is for anyone looking to improve their metabolic health, manage their weight, boost their energy levels, support their workout routine, and live happier and longer lives.
If you are under 16 years of age, pregnant, or suffer from the following conditions, please consult a medical professional before using Lumen:
Additionally, Lumen's nutritional recommendations may not be suited for people with:
For other medical problems, please check with your doctor first.
Lumen is under warranty for one year, starting from the date of account activation, or 10 days after your purchase, whichever is earlier. If your device or charging dock develop a fault caused by manufacturing defects during that period, we'll fix or replace them free of charge. You can read our full warranty policy here.
Your Lumen can be returned for a full refund within 30 days of receiving it, if it is unopened. We want you to be satisfied with your Lumen, so please reach out to Customer Support if you’re having problems. Read our full refund policy.