[Body density assessment utilizing skinfold thickness and age in Japanese women].

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in women. Subjects of the study were 512 healthy women aged 18-66 years in or near Nagasaki City. The dependent variable in the multiple regression equation, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 30.1, range 18-66 yrs.), weight (mean 52.6, range 38.0-83.3 kg), height (mean 157.0, range 142.0-172.0 cm), and body density, (mean 1.04125, range 0.98806-1.08650 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.4% to 48.3%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in women were compared. The best-fitting and the most convenient prediction equation for body density was equation-E. The regression equation developed for predicting body density was: body density = 1.07931-0.00059 x sum of three skinfolds(mm)-0.00015 x age (MR = 0.77 and SE = 0.0089). The equation was cross-validated on a different sample of 46 women. The correlation coefficient between predicted and hydrostatically determined body density was 0.813 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese women, aged 18-50 yrs, with percent body fat 17 to 34%.