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, 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.