Your breath knows
what your body needs
One breath into Lumen's CO2 sensor tells you whether you're burning fat or carbs, and delivers a personalized nutrition plan for the day ahead to enhance your metabolic health.
One breath into Lumen's CO2 sensor tells you whether you're burning fat or carbs, and delivers a personalized nutrition plan for the day ahead. No diets. No guessing.
Lumen is the world’s first scientifically validated hand-held device to accurately measure metabolism at the mitochondrial level. Once available only to elite athletes and in hospitals and clinics, metabolic testing is now accessible to everyone
Lumen is the world’s first scientifically validated
hand-held, portable device to accurately measure metabolism on a cellular level. Once available only to top athletes, in hospitals and clinics, metabolic testing is now available to everyone.
As seen on
From signal to action
Actionable insight,
right when you need it.
Breathe
One guided breath. Lumen's CO₂ sensor reads whether you're burning fat or carbs right now.
Understand
Your breath, sleep, meals and workouts become one Body State: what's happening, and why.
Act
One next best action (eat, move, fuel or recover), timed while it can still change your day.
Track
Every breath moves the needle. Your live compass shows if you're on track to metabolic health.
Benefits
Measure your metabolism daily
and optimize your metabolism
Teach your body to shift
to fat burn easily
One breath reveals whether you are burning carbs or fat. Receive tailored daily nutrition guidance and timely alerts when your body is stuck on burning carbs
Preserve muscle and
enhance fat burn
Spot early indicators that your body may be breaking down muscle mass. Know exactly when to increase dietary protein or prioritize strength training to protect lean tissue.
Adapt to hormonal shifts and reclaim your energy
How your body utilizes fuel changes with age. Lumen shows you what meals, nutrient timing, and training routines match your current biology.
Fuel your workouts
and recover smarter
Breathe before you train to see if your body is ready to burn fat or needs carbs first. Breathe after to see how it responded and what your body needs to recover.
Keep your metabolism flexible
Track how easily your body switches fuels, a key marker of healthy aging, and build the habits that keep it efficient
The proof behind the experience
Trusted by doctors and health experts
Hear why leading doctors and researchers recommend tracking your metabolism every day
A metabolic test that fits in your hand
The science isn’t new, but the technology is
We started Lumen because we believe everyone should have access to the insights they need to understand their body and optimize their health. It’s our life’s work - and we love every minute of it.
Drs. Michal & Merav Mor
Lumen Co-Founders & Sisters
Validated by peer-reviewed
scientific research
Trusted by top universities and research centers
around the world.
Your breath reveals your fuel ratio
RER — Respiratory Exchange Ratio — is the ratio of CO2 you exhale to O2 you consume. When it’s low, you’re burning fat. When it’s high, you’re burning carbs. One breath tells the whole story.
The missing link
Everything you already track,
finally adding up
Your ring sees sleep. Your watch sees load. Your log sees meals. One breath into Lumen shows what it all did to your body — fat burn or carb burn — and what to do about it today.
Get Lumenworks with
Real people. Real results.
Sharon lost 30 lbs coupling
Lumen with GLP-1
Nadia lost 3% body fat with Lumen
Amy lost 26 lbs on her
journey with Lumen
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’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.
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 critical for disease prevention and helps with managing weight, improved insulin sensitivity, higher energy levels, better sleep, and even longevity.
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.
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.
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, breastfeeding, or suffer from the following conditions, please consult a medical professional before using Lumen:
Diabetes
Severe asthma
COPD
Additionally, Lumen's nutritional recommendations may not be suitable for people with:
Kidney disease
Cancer
Thyroid disorder
Yes, we offer a one-year warranty from the date the device is delivered to you. If your device or charging dock are damaged by manufacturing defects during that period, we'll fix or replace them free of charge. You can read our full warranty policy here.
* As reported in 2024 Lumen user data analysis