Question

the charged body loses its charge if we touch it with our hands why

Answer 1

this happens because of temperature difference. there is exchange between molecules of our hands and charged body.
what the thing happens is
there is exchange from a body of higher temperature to body of lower temperature

Answer 2

This happens due to earthing and it only happens if u have wear sleepers as ur body too contain some charges so the charges flows to the earth.

Hope it will help u dear...