Handheld breath test accurately detects fat burning by measuring acetone in a single exhalation (nature.com)

• Device measures breath acetone, a volatile compound from fatty acid breakdown, indicating ketosis.
• Smartphone app guides exhalation to improve accuracy; acetone is separated before measurement.
• Validated against PTR-MS on 12 volunteers under exercise and dietary interventions.
• Commercialized as Nutrion by ETH spin-off Alivion; patent held by ETH Zurich.

"Researchers at ETH Zurich developed a handheld breathalyser that measures acetone in breath to detect when the body is in ketosis. Tested on 12 volunteers, the device showed strong agreement with gold-standard PTR-MS. It uses a smartphone app to guide exhalation and separates acetone before measurement, overcoming humidity issues. The device is commercialized as Nutrion by ETH spin-off Alivion. The study was published in Device."