Body composition assessment in overweight women: validation of air displacement plethysmography

Summary Purpose 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 m 2 ). Subjects/Methods 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 m 2 ) 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. Results Validity data comparing ADP and DXA demonstrated no significant difference in FM ( ADP ‐ DXA FM  = 0·99 kg; P  = 0·113), FFM (0·98 kg; P  = 0·115) and % BF (1·56%; P  = 0·540). Reliability data for ADP between the first and second trials showed no significant difference in FM ( P  = 0·168; ICC  = 0·994; SEM  = 0·668), FFM ( P  = 0·058; ICC  = 0·973; SEM  = 0·892) or % BF ( P  = 0·121; ICC  = 0·971; SEM  = 0·813). Conclusions 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.