DETECTION OF SMALL CHANGES IN BODY-COMPOSITION BY DUAL-ENERGY X-RAY ABSORPTIOMETRY

The ability of dual-energy x-ray absorptiometry (DEXA) to detect small changes in body composition was studied in 17 men and women during a dehydration-rehydration protocol. Scale weight (BW) and total mass (TM ) from DEXA were highly related (r > 0.99) as were estimates of fat-fr ee mass (r = 0.99) and percent fat (r = 0.97) from DEXA and densitomet ry. Changes in BW of almost-equal-to 1.5 kg due to fluid loss and pin were highly correlated (r = 0.90) with both changes in TM and soft-tis sue mass (STM) by DEXA but less so (r = 0.67) with changes in lean-tis sue mass (LTM). Mean changes in TM, STM, and LTM were not different (P > 0.05) from changes in BW. Estimates of bone mass and fat were unaff ected by changes in hydration. We conclude that DEXA is able to detect small individual changes in TM and STM and is also useful for detecti ng group changes in LTM.