The device has four electrodes that the user touches with the thumb and one finger of each hand. These send a safe current through the body, measuring the voltage drop as the current flows up one arm and down the other.
A body fat value serves as a main index to determine fatness, which is known to cause many adult diseases.
Since fat occupies 17 percent of a human body and contains little water, it offers less electrical resistance. The users enter their body weight and the device makes its best guess of the percentage of fat in the body, reported the online edition of New Scientist.
The device can reveal just how much body fat a person is carrying, the company said. However, it will only be accurate if finger contact is perfect.
To stop people accidentally or deliberately fooling the machine, a subject must gradually increase finger pressure while the device sends the test voltage. Once calibrated, it can weigh up fat content more accurately, it said.