Evaluation of partial body composition using bioelectrical impedance in Japanese children.

To clarify the growth pattern of body composition by body part for the management of childhood obesity, we measured body fat and muscle using BIA (bioelectrical impedance analysis) in 685 Japanese elementary schoolchildren (aged 6-11 years). The growth patterns of percentage body fat (%BF), fat mass (FM), and muscle mass (MM) were examined throughout the whole body and in various body parts. The %BF of the whole body was greater in females than in males, and this difference widened with age. The %BF, FM, and MM in each body part showed similar growth patterns and gender differences to those of the whole body. The mean %BF of the left limbs was higher than that of the right limbs at all age groups. BMI was strongly correlated with %BF in both sexes. In conclusion, the compositions of all body parts change similarly with age, and gender differences are also similar in childhood. The effect of one's dominant arm on body composition is seen at a young age. The accumulation of body composition data according to body part is indispensable for understanding childhood body composition and managing obesity.