A portable system is provided for measuring a ketone, such as an acetone, in the breath or other bodily fluid of a user. The system includes a portable measurement device that analyzes fluid samples and generates corresponding ketone measurements. The portable measurement device communicates with an application which runs on a smartphone or other mobile device of the user. The application tracks, and generates graphs of, the ketone measurements, and may include various features for facilitating the analysis of the measurements.
