What Is the Heaviest Part of the Body?

The general purpose of skin is to protect internal organs from dehydration, physical assaults, micro-organisms and radiation. One human leg, which includes numerous structures from many other bodily systems, accounts for around 10 percent of a person's body mass. At an average of 3.4 pounds, the heaviest internal organ is the liver; the second heaviest is the brain, which weighs around 2.8 pounds.