Practical Considerations for Body Composition Assessment of Adults with Class II/III Obesity Using Bioelectrical Impedance Analysis or Dual-Energy X-Ray Absorptiometry

Purpose of Review The purpose of this review is to explore the practical considerations for body composition assessment of adults with class II/III obesity. Studies assessing adults (18-64 years) with a body mass index (BMI) >= 35 kg/m(2) with bioelectrical impedance analysis (BIA) and/or dual-energy X-ray absorptiometry (DXA) were included. Recent Findings Twelve studies met inclusion criteria. Five considerations were identified: variances in equipment and technology, equipment weight capacity, subject positioning, tissue penetration, and total body hydration. In subjects with BMI >= 35 kg/m(2), BIA overestimated fat-free mass with scaling errors as BMI increased. DXA provided accurate and reliable body composition measures, but equipment-related barriers prevented assessment of some taller, wider, and heavier subjects. Summary BIA is an unreliable method to assess body composition in class II/III obesity. Advancements in DXA tech-nology (e.g., iDXA), methodology (e.g., subject positioning, longer scan times), and more inclusive testing criteria (e.g., use equipment limits not just BMI) may improve access and understanding of body composition in this cohort.