title: Measurement of body fat in young and elderly women: comparison between a four-compartment model and widely used reference methods.
abstract: Body composition was measured in twenty young females aged 19-27 years and eighteen elderly females, aged 65-78 years by densitometry (underwater weighing), deuterium oxide dilution and dual-energy X-ray absorptiometry (DXA). From body weight, bone-mineral content, total body water and body density, percentage body fat (BF%) was calculated using a four-compartment model. BF% obtained by this four-compartment model was regarded as a reference method and BF% obtained by the single methods were compared with this value. Differences in BF% from the four-compartment model minus the single methods were 2.1 (SD 1.2) for densitometry, 3.1 (SD 1.8) for DXA and -0.6 (SD 0.9) BF% for deuterium oxide dilution in the young women. In the elderly women these values were -0.6 (SD 2.3), 5.3 (SD 3.8) and 0.7 (SD 2.2) BF%. When a three-compartment model (calculated from body density and total body water) was compared with the four-compartment model, the bias was 0.4 (SD 0.3) BF% in the young and 0.0 (SD 0.3) BF% in the elderly women. From the mineral and water fractions in the fat-free mass the true density of the fat-free mass was calculated as 1.1070 (SD 0.0047) kg/l in the young females and 1.0970 (SD 0.0088) kg/l in the elderly women (P < 0.001). This study shows that the single methods have considerable mean and individual biases compared with the four-compartment model, but that a three-compartment model calculated from density and total body water offers an acceptable alternative. The difference in calculated density of the fat-free mass between the young and the elderly women shows the need to adapt Siri's formula for specific groups.
authors.affiliation: Department of Human Nutrition, Wageningen Agricultural University, Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Bergsma-Kadijk
authors.forename: B
authors.initials: B
authors.lastname: Baumeister
authors.forename: P
authors.initials: P
authors.lastname: Deurenberg
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D000367:Age Factors; D000368:Aged; D001823:Body Composition; D001834:Body Water; D001835:Body Weight; D015519:Bone Density; D003720:Densitometry; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D008954:Models, Biological