The largest component of the body is water, accounting for about 50% 60% of body weight, followed by fat. Others are proteins and sugars contained in muscles, and inorganic substances contained in bones. Body fat percentage refers to the ratio of body fat to body weight. The body fat rate of boys is about 17-23%; the body fat rate of girls is about 20-27%; 14~20% of boys under 30 years old; 17~2...