Modern Japanese BCA devices utilize Multi-Frequency Bioelectrical Impedance Analysis (MF-BIA). By sending currents ranging from $5\text{ kHz}$ to $1000\text{ kHz}$, these devices can distinguish between water held outside the cells and water held within the cell membranes.

A critical metric provided by these devices is the Phase Angle. In Japanese clinical settings, the Phase Angle is used as a "Cellular Vitality" score. A high Phase Angle indicates strong cell membranes and high lean body mass, while a low angle can be an early warning sign of nutritional deficiency or cellular fatigue, allowing for preventive intervention before a disease state occurs.