Change of body composition over an eight year period among Japanese university students

This study examined the change of body composition in Japanese university students. Subjects were university students divided into two groups by sex for two different time periods: 67 males and 46 females for 1986-1987 and 47 males and 64 females for 1994-1995. Body height, weight, and underwater weight were measured to estimate the percentage of body fat. The fat mass index (FMI) was applied after adjusting fat mass and the fat-free mass index (FFMI) applied after adjusting fat-free mass for body physique by dividing (body height)2. The mean body mass index (BMI) increased from 1986-1987 to 1994-1995 in males and decreased in females, although there were no statistical differences between two time periods in both sexes. The FMI indicates that in 1994-1995 males had significantly more fat adjusted for body height than in 1987. Females in 1994-1995 had significantly less FFMI than those in 1986 despite FMI similar to that of 1986. Our results thus warn against a trend toward excessive thinness in collegiate females and insufficiency of evaluating body composition using the BMI alone.