How does a machine that tells your body fat percentage work?

Question

I know that it takes into consideration your height, weight, age, and sex... but why do you have to hold those handles?

Answer 1

they don't work.

those machines use biolectrical impedance as an attempt to gauge the level of body fat that the user has. they are extremely inaccurate and are effecting greatly just by the level of hydration that the user has.

the cheapest most effective method is to get some hand calipers that use skin fold measurements from various sites on your body..

Answer 2

good question ita all about pressure it measures how strong u are