Clinical detection of sarcopenic obesity by bioelectrical impedance analysis.

To assess whether bioelectrical impedance analysis (BIA) provides clinically useful information on body composition beyond that obtained from measuring height and weight, we clinically classified 306 obese patients (233 females and 73 males) into tertiles of increasing fat-free mass estimated by BIA. Because fat-free mass by BIA is an estimate of lean body mass, the lowest tertile was clinically defined as sarcopenic obesity (reduced lean body mass), as contrasted with proportionate or muscular obesity in the next two tertiles. Fat mass in patients in each of the above tertiles based on BIA was then compared with fat mass estimated by using the equations of Garrow and Webster with body mass index (weight/height2). BIA-estimated fat mass was 4.3 kg greater in the sarcopenic group (n = 102) than predicted from body mass index. Fat mass predicted by BIA in the proportionate (n = 102) and muscular (n = 102) groups differed by less than the SEE of fat mass predicted by BMI. In premenopausal women at increased risk of breast cancer BIA showed a high prevalence of sarcopenic obesity (28/30) in these women at normal body mass indexes. Thus, BIA may be clinically useful for demonstrating sarcopenic obesity, but additional studies are needed to determine the metabolic and clinical significance of sarcopenic obesity.