Is it illegal to throw in a ball with the lower body turned in one direction ( i e below waist)and the upper body in another? That is if I twist myself and try to throw in a ball?
It's a legal move as long as you face the field.
Law 15 doesn't prohibit it:
At the moment of delivering the ball, the thrower must:
stand facing the field of play
have part of each foot on the touchline or on the ground outside the touchline
throw the ball with both hands from behind and over the head from the point where it left the field of play