Abstract

Background: Pencil beam dual energy x ray absorptiometry (DXA) has been shown to provide valid estimates of body fat (%BF), but DXA fan beam technology has not been adequately tested to determine its validity.

Objective: To compare %BF estimated from fan beam DXA with %BF determined using two and three compartment (2C, 3C) models.

Methods: Men (n  =  25) and women (n  =  31), aged 18–41 years, participated in the study. Body density, from hydrostatic weighing, was used in the 2C estimate of %BF; DXA was used to determine bone mineral content (BMC) for the 3C estimate of %BF calculated using body density and BMC (3C_BMC). DXA was also used to determine %BF. Analysis of variance was used to test for significant differences in %BF between sexes and among methods.

Results: Women were significantly shorter, weighed less, had less fat free mass, and a higher %BF than men. No significant differences were found among methods (2C, 3C_BMC, DXA) for determination of %BF in either sex. Although not significant, Bland-Altman plots showed that DXA gave higher values for %BF than the 2C and 3C_BMC methods.

Conclusion: DXA determination of %BF was not different from that of the 2C and 3C_BMC models in this group of young adults. However, to validate fan beam DXA fully as a method for body composition assessment in a wide range of individuals and populations, comparisons are needed that use a 4C model with a measure of total body water and BMC.