The human body has a significant amount of water in it. The amount of water depends on a person’s age, and the amount of fat that is stored in the body.
Water can be as much as 75-78% of a new baby’s total weight. The percentage of water weight in the body will decrease throughout a person’s lifetime.
Fat contains less percentage of water than muscle tissue does. So the less lean a person is, the less of their body weight is made up of water. The percentage of water in the body in extreme obese people can reach as low as 45%.