Measures of body composition. Their relationship to blood pressure and use in epidemiologic research

The association between "overweight" and increased risk of high blood pressure has long been recognized. The quantification of overweight into various aspects of body composition and the relationships of these aspects to blood pressure remain important areas of current research. The manner in which adipose tissue is distributed over the body is proving to be another important risk factor. Methodologies for assessing body composition include a variety of approaches commonly used in epidemiologic studies, ranging from simple indices (e.g., body mass index) to estimation of total body fat mass from equations based on skinfolds and other anthropometry, to newer approaches incorporating bioelectric impedance. Refined laboratory methods for assessing body composition are important in the study of small groups and in the development of predictive equations. These refined methods include the traditional approaches of hydrostatic weighing and K40 determinations, as well as newer improvements on these techniques incorporating estimates of bone mineral content and total body water. Other new sophisticated methodologies include dual-energy x-ray absorptiometry and nuclear magnetic resonance imaging. The approach to assessing body composition may vary among age groups; methodologies applicable to children may not work for the elderly.