B.F.D. is a measurement of the skin resistance of acupuncture points. If there is a disturbance in an organ, tissue, or the energetic condition of organs, the resistance of the corresponding acupuncture point changes. This measurement is important for gaining an understanding of the body's energetic state and the condition of various organ systems. 

In this testing method, the therapist measures the start and end points of the meridians on the hands and feet. As a client, you will take off your shoes and socks and hold a hand electrode. The therapist will take the measuring pen and place it on the acupuncture points. The measuring device will then display a value. B.F.D. measurements are also taken in relation to bioresonance equipment.