The study presents reference values for body composition and bone mineral density (BMD) obtained from dual energy X-ray absorptiometry (DXA) measurements in the National Health and Nutrition Examination Survey (NHANES) dataset. The data, collected from 1999 to 2004, cover a wide age range (8 to 85 years) and include subjects from three major ethnic groups: Non-Hispanic Whites, Non-Hispanic Blacks, and Mexican Americans. The reference values are normalized to age, height, or lean mass for children and are age-specific for adults. The study also developed an obesity classification scheme based on Fat Mass Index (FMI), which is calculated as fat mass divided by height². This scheme aims to provide more accurate obesity classification by focusing on fat mass rather than total body weight. The reference values are intended to be useful in various clinical and research settings, including the evaluation of abnormalities in bone and body composition, establishing reference ranges, and designing clinical trials. The study highlights the importance of considering gender and ethnicity in the interpretation of DXA results and provides a comprehensive set of reference curves and percentiles for different age groups and ethnicities.The study presents reference values for body composition and bone mineral density (BMD) obtained from dual energy X-ray absorptiometry (DXA) measurements in the National Health and Nutrition Examination Survey (NHANES) dataset. The data, collected from 1999 to 2004, cover a wide age range (8 to 85 years) and include subjects from three major ethnic groups: Non-Hispanic Whites, Non-Hispanic Blacks, and Mexican Americans. The reference values are normalized to age, height, or lean mass for children and are age-specific for adults. The study also developed an obesity classification scheme based on Fat Mass Index (FMI), which is calculated as fat mass divided by height². This scheme aims to provide more accurate obesity classification by focusing on fat mass rather than total body weight. The reference values are intended to be useful in various clinical and research settings, including the evaluation of abnormalities in bone and body composition, establishing reference ranges, and designing clinical trials. The study highlights the importance of considering gender and ethnicity in the interpretation of DXA results and provides a comprehensive set of reference curves and percentiles for different age groups and ethnicities.