A man carrying a bucket full of water on  his right hand always leans towards his left  hand. Why? 
When a man carries a bucket full of water on  his right hand without leaning towards his left,  the location of the center of gravity of the  system (man + bucket full of water) changes  and the system becomes unstable. This  produces a net torque about the center of  gravity of the man and this torque tries to rotate  the man to the right. In order to cancel this  torque, the man has to lean to the left so that the  center of gravity of the man and the bucket full  of water as a whole lies within the base and the  stable equilibrium is achieved. Thus the man  carrying the bucket full of water on his right  hand always leans towards his left hand. For  the same reason, a man carrying a load on his  back leans forward.