Hand-held gadget measures fat burning via breath

Researchers have created a portable device that detects when the body starts burning fat when dieting or during exercise.

The device detects the acetone content in exhaled breath nearly as accurately as a mass spectrometer. Acetone is the by-product of fat metabolism that is exhaled via the lungs. It is made when the body burns fat instead of carbohydrates such as sugar.

The device is very reminiscent of...