Breathalyser can tell if you are burning fat from a single exhalation

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A handheld breath test can accurately measure when the body is burning fat in real time1. The device could be used by people trying to manage weight loss without them having to wait weeks to see a shift on the scales, although researchers say that it should be tested in 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 diets that are low in carbohydrates or through high-intensity exercise, but it is difficult to measure in real time. Consumer breath-testing devices exist, but many struggle to reliably detect this state in the body2 or haven’t been scientifically validated3. More-accurate methods to measure changes in fat stores over time, such as magnetic resonance imaging and body composition scanning, require people to visit a clinic. The 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 to develop the device. The fat-burning breathalyser is designed for use at home. Users breathe into a mouthpiece, and the device measures the level of acetone, a volatile compound produced during the breakdown of fatty acids and released in the breath in response to exercise, fasting and dietary interventions. What sets it apart from other breathalysers, according to the inventors, is the smartphone app that guides the user’s exhalation, improving accuracy. The device also separates acetone from the breath before measuring it. Other devices try 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, that has commercialized the device, called Nutrion. ETH Zurich holds the patent for the technology. Small trial The research team tested the accuracy of the device on 12 healthy volunteers. The participants underwent a variety of exercise and dietary interventions that were designed to produce rapid or gradual shifts in metabolism. Measurements of breath acetone from the detector were compared with readings obtained from proton transfer reaction time-of-flight mass spectrometry (PTR-MS), a highly accurate laboratory technique that is considered the gold standard for breath analysis. The handheld device showed strong agreement with PTR-MS measurements, the authors report. Enjoying our latest content? Log in or create an account to continue Access the most recent journalism from Nature's award-winning team Explore the latest features & opinion covering groundbreaking research