A Handheld Metabolic Device (Lumen) to Measure Fuel Utilization in Healthy Young Adults: Device Validation Study

Abstract

Background Metabolic carts measure the carbon dioxide (CO2) produced and oxygen consumed by an individual when breathing to assess metabolic fuel usage (carbohydrates versus fats). However, these systems are expensive, time-consuming, and only available in health care laboratory settings. A small handheld device capable of determining metabolic fuel usage via CO2 from exhaled air has been developed. Objective The aim of this study is to evaluate the validity of a novel handheld device (Lumen) for measuring metabolic fuel utilization in healthy young adults. Methods Metabolic fuel usage was assessed in healthy participants (n=33; mean age 23.1 years, SD 3.9 years) via respiratory exchange ratio (RER) values obtained from a metabolic cart as well as % CO2 from the Lumen device. Measurements were performed at rest in two conditions: fasting, and after consuming 150 grams of glucose, in order to determine changes in metabolic fuel usage. Reduced major axis regression and simple linear regression were performed to test for agreement between RER and Lumen % CO2. Results Both RER and Lumen % CO2 significantly increased after glucose intake (P<.001 for both) compared with fasting conditions, by 0.089 and 0.28, respectively. Regression analyses revealed an agreement between the two measurements (F1,63=18.54; P<.001). Conclusions This study shows the validity of Lumen for detecting changes in metabolic fuel utilization in a comparable manner with a laboratory standard metabolic cart, providing the ability for real-time metabolic information for users under any circumstances.

The Effects of Metabolism Tracker Device (Lumen) Usage on Metabolic Control in Adults with Prediabetes: Pilot Clinical Trial

“…The use of the metabolic cart for optimizing nutritional and metabolic requirements can be referred to as ambitious or challenging, due to the hazardous nature of this method, since it requires arrival to the clinic and is time consuming. The use of Lumen, which has been found to be in agreement with the metabolic cart [ 21 ], can be performed by oneself daily, in a household environment. This simplifies the assessment of the metabolic flexibility degree, which can serve as a personalized lifestyle intervention tool.…”

“…Lumen is a novel handheld exhaled CO 2 measurement device which was recently found to be in agreement with indirect calorimetry in providing an accurate assessment of metabolic fuel usage [ 21 ]. This is incorporated into a comprehensive lifestyle intervention using a mobile phone application to provide daily personalized nutritional and lifestyle recommendations.…”

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“…There currently exist products that, although not continuous sensing devices, claim to assess metabolic end products in exhaled air to give indications about the user’s metabolic state [ 53 ]. Although an interesting proposal that demonstrates reasonable validity in initial studies, the product is yet to be widely tested and lacks FDA recognition.…”