A prototype portable breath acetone analyzer for monitoring fat loss.

Acetone contained in our exhaled breath is a metabolic product of the breakdown of body fat and is expected to be a good indicator of fat-burning. Typically, gas chromatography or mass spectrometry are used to measure low-concentration compounds in breath but such large instruments are not suitable for daily use by diet-conscious people. Here, we prototype a portable breath acetone analyzer that has two types of semiconductor-based gas sensors with different sensitivity characteristics, enabling the acetone concentration to be calculated while taking into account the presence of ethanol, hydrogen, and humidity. To investigate the accuracy of our prototype and its application in diet support, experiments were conducted on healthy adult volunteers. Breath acetone concentrations obtained from our prototype and from gas chromatography showed a strong correlation throughout the experiments. Moreover, body fat in subjects with a controlled caloric intake and taking exercise decreased significantly, whereas breath acetone concentrations in those subjects increased significantly. These results prove that our prototype is practical and useful for self-monitoring of fat-burning at home or outside. Our prototype will help to prevent and alleviate obesity and diabetes.