Everything you need to optimize your health in the palm of your hand

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.

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.

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.

Select "Checkout with HSA/ FSA." If you are logged into Shop Pay, please select "Check out as guest."

Complete your delivery and billing details, and then click "Pay now."

From there, enter your HSA or FSA card details and complete your checkout as usual. If you don't have your card handy, you can enter in a credit card, and Flex will send you an itemized receipt you can submit to your provider for reimbursement.

Yes, you can cancel your membership at any time. Cancellations will take effect on the next billing cycle.

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.

Your membership will start when you activate your account after receiving your Lumen device, or 10 days after your purchase, whichever is earlier.

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 suited for people with:

• Kidney disease
• Cancer
• Thyroid disorder

‍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.

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.