Researchers have developed a handheld breathalyser designed to show when the body is burning fat for energy, known as ketosis. The device measures acetone in a user’s breath and, in a small study, produced results close to conventional laboratory tests, potentially making metabolic monitoring more accessible outside clinical settings.

The study involved 12 participants across different diet and exercise conditions. To improve accuracy, the device filters moisture and contaminants, while a companion app guides breathing pressure and sample timing; the commercial version is called Nutrion, and possible uses include monitoring GLP-1 treatment effects and helping athletes manage training.