Your head does not weigh more than your whole body.
Your head weighs around 8 to 11 lbs depending on the size of the head.
An average adult human weighs around 120 lbs to 130 lbs and your head only weighs in at around 8 to 11 lbs so the rest of your body actually weighs more than your head.
However your head is pretty heavy though when compared to other body parts and according to research your head is the heaviest body part.
A babies head weighs around 1 to 2 lbs and a child's head weighs around 4 lbs and a teenagers head weights around 7 to 8 lbs.
Your head is pretty heavy but not the heaviest part of the body and certainly not heavier than your whole body.