Comparison of body size and composition between young adult Japanese-Americans and Japanese nationals in the 1980s

Background: Data on body composition of American-born Japanese (Japanese-Americans) are scarce. Studies on differences of body composition between Japanese-Americans and Japanese nationals at various stages of life as well as at various times of measurements are useful for understanding the impact of lifestyle changes on body composition in the two societies. Aim: To see the differences in body size and composition between young adult Japanese-Americans and Japanese nationals. Subjects and Methods: Body size and composition of 50 Japanese-Americans consisting of 28 males and 22 females ranging in age from 18 to 23 years were compared with Japanese nationals matched for age and height. Body composition was measured using the underwater weighing method. The study was conducted in the 1980s in the USA and Japan. Results: The average percentage body fat of males was 13.7% for both Japanese-Americans and Japanese nationals, and that of females was approximately 24% for both groups, even though Japanese-American males and females had significantly greater body weight, fat-free mass, and body mass index than Japanese nationals. Conclusion: Although young adult Japanese-Americans showed larger body size than Japanese nationals, their percentage fat did not differ at this stage of life in the 1980s.