Monitoring fat metabolism may soon become as simple as taking a breath. Researchers at ETH Zurich have developed a portable handheld breathalyzer that accurately measures acetone, a natural by-product released when the body burns fat instead of carbohydrates. Resembling a standard alcohol breathalyzer and paired with a smartphone app, the device enables individuals to monitor their metabolic state non-invasively, eliminating the need for blood tests or laboratory equipment. In a validation study involving 312 breath measurements from 12 adults, the device demonstrated accuracy comparable to a high-precision mass spectrometer, the current laboratory gold standard, across different dietary patterns and exercise intensities. A specially designed molecular filter and app-guided breathing protocol ensure highly reproducible results by selectively measuring deep-lung breath while minimizing interference from food, beverages, and other exhaled compounds.

      This innovation has the potential to transform personalized nutrition and metabolic care. Real-time monitoring of fat metabolism could help individuals optimize weight-loss strategies, evaluate the effectiveness of ketogenic diets, and support management of metabolic disorders such as diabetes. Researchers are also exploring its use in monitoring patients receiving GLP-1–based weight-loss therapies, as well as children with epilepsy undergoing ketogenic treatment. Developed by the ETH Zurich spin-off Alivion AG and launched under the name Nutrion, the device represents an important step toward accessible, point-of-care metabolic monitoring. If validated in larger clinical studies, this technology could empower both clinicians and patients with a simple, accurate, and non-invasive tool for precision metabolic health management.