Comparison of amplitude-mode ultrasound versus air displacement plethysmography for assessing body composition changes following participation in a structured weight-loss programme in women.

The purpose of this study was to compare body composition changes as measured by A-mode ultrasound (US) versus a criterion densitometry-based measure, air displacement plethysmography (ADP), over a 4-week weight-loss protocol in healthy, non-obese young women. Twenty healthy, young female volunteers were provided with customized dietary plans for the length of the study intended to facilitate a 500 calorie-a-day deficit. Subjects also performed 3 h a week of supervised aerobic exercise. Per cent fat mass and lean body mass were obtained via ADP and US both pre- and postintervention. Pretesting, post-testing and delta data for %fat resulted in no significant differences in mean values along with a slope of the regression line no different than one and a y-intercept no different than zero (P<0·05). Similar to %fat values, pretesting, post-testing and delta data for fat-free mass resulted in no significant differences in mean values along with a slope of the regression line no different than one and a y-intercept no different than zero (P<0·05) with the exception of the delta for slope (0·39, P = 0·04). The current findings indicate that US can provide a similar degree of accuracy for tracking group-based fat loss in women compared to ADP. Given the low-cost relative to DXA and ADP, researchers and practitioners therefore can consider US as a viable option for monitoring group-based changes in body fat over time.