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Learn about your metabolism with Lumen

How runners can know more about their bodies with one breath

Lumen is a tiny device designed to help runners hack their metabolism. This tool requires its users to breathe into it once a day in order for it to assess and give insights about their metabolic function. Its designers set out to create a tool that gave people an easy window into how their body works, from the comfort of their home. The user is provided with opportunities to optimize their metabolic function through foods recommended by the app. With lots of settings to address your personal goals, Lumen can help you learn about your body and keep your health on track.

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How to use it

Lumen requires both a physical device and a free app downloaded to the user’s phone. As you breathe into the device, your results are recorded through the app. Users have to breathe into it several times a day, beginning at breakfast (before you’ve consumed anything, including coffee) and before bed.

This process begins with a calibration day, where you breathe into it five times in one day for Lumen to assess your baseline, which is a combination of your CO2 range (which begins with a fasted breath in the morning) and a measurement of your lung capacity. The calibration day requires a lot of breathing to obtain both of these measurements. You’ll also be asked questions about your exercise habits, daily activity levels and what goals you have for your fitness. The options are healthy weight loss, metabolic health (focused on building good habits) and fitness performance (optimizing nutrition to support and improve performance).

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After your breath in the morning, Lumen will tell you if you’re burning carbs or fat and then suggest a daily nutrition plan. After four weeks of daily use, you’ll receive a Lumen flex score, which is a number assigned to you based on your metabolic flexibility (your body’s ability to switch between burning carbs and fat). As your flexibility improves, so does your score.

The science behind it

C02 concentration is measured through your breath. High CO2 concentration means your body is burning carbohydrates, while low CO2 levels means your body is burning fat. Measuring metabolic fuel usage allows the user to track their metabolic flexibility, which is the body’s ability to move between fat and carbs as its fuel source.

A metabolic flexibility score is useful for a runner who’s looking to use fat as their main source of fuel. For example, low-carb, high-fat diets have been anecdotally linked with improved ultrarunning performances. Lumen can help a runner know if they’ve reached a low-carb, high-fat state.

Best applications for runners

For runners, Lumen does one thing really well: it can help users to know if they’re adequately fuelled for a workout. Running on empty is a slippery slope, and a habit that can get people into trouble over the long term. A quick breath into Lumen pre-workout will let you know if you’ve got enough sustenance to get you through your session, or if a snack is in order. RED-S, or relative energy deficiency in sport, is a product of under-fuelling and sustained (unhealthy) weight loss. Lumen can help runners catch when they’re under-fuelling, especially in the context of a workout.

For me, this was my favourite application of Lumen. If I’d gone a couple hours without eating I’d check to see if I was good to start my run or if I should hold off and eat something first. Sometimes, even when I didn’t feel that hungry, Lumen recommended I have a snack. Post-workout, Lumen would also let me know the effect the workout had on my body, which was another way to tell if I’d fuelled properly during.

Another application is the meal ideas and nutrition plan. This is a great way to get inspired and keep you on track in the kitchen, especially if you’re someone who’s new to cooking for yourself.

The Lumen device costs $299 USD and ships for free worldwide.

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