A Breathalyzer That Tells You When You're Burning Fat Is Already on Sale

ETH Zurich researchers built a handheld device that detects fat burning by measuring acetone in your breath. Published in Device on July 21, 2026, it is already sold as Nutrion by Alivion. A companion phone app fixes errors from breathing unevenly — similar to how at-home blood sugar monitors combined sensors with software to leave clinics. Tested on 12 people; larger studies are needed.