Within- and Between-Day Reliability of Laboratory-Based Body Composition Assessment Methods

Document Type

Article

Publication Title

British Journal of Nutrition

Abstract

This study examined the within- and between-day reliability of commonly employed laboratory-based body composition assessment methods. Eighteen healthy adults reported to the laboratory on two occasions, separated by 1–2 days, and were assessed with multiple methods under standardized conditions. These included two dual-energy X-ray absorptiometry (DXA) scanners with manual or automated regions of interest, air displacement plethysmography (ADP) with measured or estimated thoracic gas volume, two multi-frequency bioelectrical impedance analyzers (MFBIA), single-frequency BIA (SFBIA), and bioimpedance spectroscopy. Within-day reliability was established via immediate test-retest assessments at the first visit (technical error), and between-day reliability by repeating assessments at the second visit (technical plus biological error). Within- and between-day measures were evaluated using technical error of the measurement (TEM) and intraclass correlation coefficients (ICCs). For body fat percentage, within-day TEMs ranged from 0.03–0.70%, with ICCs of 0.993–1.000, while between-day ranged from 0.37–1.24%, with ICCs of 0.965–0.998. For fat and fat-free mass (FM and FFM), within-day TEMs ranged from 0.02–0.53 kg, with ICCs of 0.998–1.000 for FFM and 0.992–1.000 for FM. Between-day TEMs ranged from 0.26–0.90 kg for FM and FFM, with ICCs of 0.995–0.999 for FFM and 0.955–0.998 for FM. Across metrics, DXA demonstrated the best reliability, followed by one MFBIA analyzer and ADP with predicted thoracic gas volume. Overall, laboratory-based body composition devices provide excellent within- and between-day reliability under standardized conditions, though observed differences in error may influence method selection when tracking small body composition changes.

Research Highlights

  • The Problem: The study evaluates the within-day and between-day measurement reliability of standard laboratory-based body composition assessment instruments.

  • The Method: Test-retest assessments conducted on 18 healthy adults across two laboratory sessions separated by 1–2 days utilizing dual-energy X-ray absorptiometry, air displacement plethysmography, multi-frequency bioelectrical impedance analysis, single-frequency bioelectrical impedance analysis, and bioimpedance spectroscopy.

  • Quantitative Finding: Within-day body fat percentage technical error of measurement ranged from 0.03–0.70% with intraclass correlation coefficients of 0.993–1.000; between-day body fat percentage error ranged from 0.37–1.24% with coefficients of 0.965–0.998; within-day fat mass and fat-free mass errors ranged from 0.02–0.53 kg with fat-free mass coefficients of 0.998–1.000; between-day fat mass and fat-free mass errors ranged from 0.26–0.90 kg with fat mass coefficients of 0.955–0.998.

  • Finding: Dual-energy X-ray absorptiometry demonstrates the highest reliability across metrics, followed by multi-frequency bioelectrical impedance analysis and air displacement plethysmography using predicted thoracic gas volume.

DOI

https://doi.org/10.1017/S0007114526107752

Publication Date

6-2026

Link to Full Text

Share

COinS