• dual energy x-ray absorptiometry;
  • fat-free mass;
  • percent body fat;
  • sensitivity;
  • sex



The purpose of this study was to evaluate the validity and reliability of air displacement plethysmography (ADP) compared to a dual energy x-ray absorptiometry (DXA) criterion for body composition measurement in overweight and obese women (BMI ≥ 25·0 kg m2).


Twenty-four overweight and obese women (Mean ± SD; Age: 36·6 ± 12·0 years; Height: 166·4 ± 5·8 cm; Weight: 86·5 ± 14·2 kg; Body Fat: 38·5 ± 3·7%; BMI: 31·3 ± 5·5 kg m2) were tested after an 8-h fast. Fat mass (FM), fat-free mass (FFM) and percent body fat (%BF) were measured by ADP and compared to values determined by the DXA criterion. FFM from DXA was calculated as lean mass plus bone mineral content. A paired samples t-test was used to test for significant differences in the body composition variables between methods. A one-way ANOVA along with intraclass correlation coefficient (ICC), SEM,%SEM and MD was used to represent reliability.


Validity data comparing ADP and DXA demonstrated no significant difference in FM (ADP-DXA FM = 0·99 kg; = 0·113), FFM (0·98 kg; = 0·115) and %BF (1·56%; = 0·540). Reliability data for ADP between the first and second trials showed no significant difference in FM (= 0·168; ICC = 0·994; SEM = 0·668), FFM (= 0·058; ICC = 0·973; SEM = 0·892) or %BF (= 0·121; ICC = 0·971; SEM = 0·813).


For overweight and obese women, ADP was found to be a valid measure of FM, FFM and %BF when compared with DXA. The reliability of ADP was supported for all body composition variables.