A portable breath test can accurately measure when the body burns fat in real time¹. The device could be used by people trying to monitor weight loss without having to wait weeks to see a change on the scale, although researchers say it should be tested on more people to confirm its accuracy.

One way to burn stored fat is for the body to be in a metabolic state called ketosis, when free fatty acids are metabolized as fuel in the liver. This state is often achieved through low-carbohydrate diets or high-intensity exercise, but it is difficult to measure in real time.

Consumer breath testing devices exist, but many struggle to reliably detect this condition in the body.² or have not been scientifically validated³. The most accurate methods of measuring changes in fat stores over time, such as MRI and body composition scanning, require people to visit a clinic. Molecules produced during fat burning, called ketones, can be measured in the blood, but this would require finger-prick blood samples, says Andreas Güntner, who studies molecular sensing at the Swiss Federal Institute of Technology (ETH) in Zurich and helped develop the device.

The fat burner breathalyzer is designed for use at home. Users breathe through a mouthpiece and the device measures the level of acetone, a volatile compound produced during the breakdown of fatty acids and released into the breath in response to exercise, fasting and dietary interventions.

What sets it apart from other breathalyzers, according to the inventors, is the smartphone app that guides the user’s exhalation, improving accuracy. The device also separates acetone from breath before measuring it. Other devices attempt to directly measure ketones from an exhalation, but the humidity of the exhaled breath, as well as the surrounding environment, can interfere with the reading, the team reports in the journal. Device. Two of the authors, including Güntner, are shareholders in Alivion, a spin-off company from ETH Zurich, which markets the device, called Nutrion. ETH Zurich holds the patent for the technology.

Little test

The research team tested the accuracy of the device on 12 healthy volunteers. Participants underwent a variety of dietary and exercise interventions designed to produce rapid or gradual changes in metabolism. Breath acetone measurements from the detector were compared to readings obtained using proton transfer reaction time-of-flight mass spectrometry (PTR-MS), a high-precision laboratory technique that is considered the gold standard for breath analysis. The wearable device showed strong agreement with PTR-MS measurements, the authors report.