Abstract
To elucidate the characteristics of body composition of the Japanese, we measured body potassium (40K) and analyzed its relation to the physique indices including subcutaneous skinfold thickness and lean body mass (LBM) . The subjects were 104 healthy Japanese adults including 17 males and 84 females whose ages ranged between 23 and 74 years (mean : 50.9±12.3) . The following results were obtained : 1. Body potassium (40K) was 122±15 g in males and 82±10 g in females. Females older than 60 years had low values of body potassium, which suggested a trend to decrease with age. 2. LBM was 52±5 kg in males and 40±6 kg in females. Slightly larger values of LBM were observed among young females. Males were 14±4 %fat and females were 25±7 %. 3. 40K and LBM of both sexes were significantly positively correlated. 40K correlated significantly with subcutaneous skinfold thickness and body density only in females. 4. Among the other physique indices, Quetelet's index and Kaup's index were relatively highly correlated with body potassium values. 5. The linear regression expressions from our results to estimate LBM from the body potassium value were : For males; Lm (kg) =0.309 K+14.054 (r=0.9), for females; Lf (kg) =0.302 K+15.388 (r=0.6), for both ; L (kg) = 0.310 K+14.071 (r=0.8), K ; potassium-40 (g) . The short forms of these relations were : For males; Lm (kg) =K/2.4, for females ; Lf (kg) =K/2.0. 6. LBM values estimated from our formula would be lower than those estimated from the formula of Forbes, and would tend to be lower, but not significantly different than those estimated from Boddy's equations.
