Body composition in Chinese subjects: relationship with age and disease.

Body composition measurement by dual energy absorptiometry was carried out in 160 men (age 45-87 years) and 407 women (age 20-88 years) consisting of volunteers and 25 men and 14 women with chronic obstructive airways disease (COAD) not receiving steroids from a hospital respiratory clinic. The objectives of this study were to provide normal reference values for adult Chinese including the elderly; to examine the effect of age and COAD on body composition; and to compare the use of body mass index (BMI) as a measure of obesity or malnutrition compared with body composition measurements. Values for body composition were different when compared with studies in the Caucasian population. In both sexes, height and lean mass decreased in a linear fashion with aging. In men, total body water increased till the 55-65 age group and then decreased. In women, total body water and bone mineral content also decreased with aging in a linear fashion. Changes in weight, BMI, fat mass and percentage fat with aging were also present in women and followed a quadratic trend. BMI was not a sensitive index of obesity or undernutrition, having approximately only 50-60% sensitivity in detecting high percentage fat or low standardised lean mass values. COAD was associated with low BMI only. Body composition measurements changes with aging, and should be used instead of BMI as a better indication of obesity or undernutrition. Reference values derived from the appropriate ethnic group should be used.