Aging is associated with increased fat mass (obesity) and reduced muscle mass (sarcopenia), even in those who have stable body weight. Therefore, it may be possible to associate obesity and sarcopenia as contributing factors, which act synergistically, on metabolic and functional impairments among the elderly population. However, there have been only few reports investigating the association of body composition with common health problems, particularly in Asian ethnic groups. Prior studies of body composition were based largely on indirect estimates, depending on anthropometric data, such as body mass index or waist circumference. Although these measures are simple, cheap and easily applicable in large epidemiological studies, they have limitations in determining the regional body composition. In contrast, bioelectrical impedance analysis (BIA), dual energy x-ray absorptiometry (DXA) and computed tomography (CT) provide a comprehensive assessment of the age-related, functional decline that is reflected in loss of muscle mass, the main component of body composition change in the elderly. BIA is easily applicable and relatively cheap. However, several reports have doubts about its accuracy. In contrast, DXA provides a higher degree of precision through only one measurement and has the ability to show exactly where fat or muscle is distributed throughout the body. DXA is emerging as a new gold standard for body composition assessment because it is very reliable and its results are extremely precise. CT has also been used to measure fat or muscle distribution at specific regions. In conclusion, assessment of body composition will be important in the clinical evaluation of common health problem particularly among the old age population.