Diagnostic Methods for Muscle Wasting in COPD: Strengths, Limitations and the Role of Nutritional Assessment

Background/Objectives: Skeletal muscle wasting is a frequent and clinically consequential comorbidity in COPD, affecting 15–50% of patients and predicting reduced exercise tolerance, impaired quality of life, hospitalization, and mortality. However, no consensus exists on the optimal diagnostic approach, and the role of nutritional assessment remains underemphasized despite its contribution to muscle depletion. Methods: This narrative review synthesizes evidence from original research, systematic reviews, and consensus statements on diagnostic methods for evaluating muscle mass, strength, physical performance, and nutritional status in COPD. Results: Computed tomography and magnetic resonance imaging offer accurate assessment of muscle mass but are limited by cost and accessibility. Dual-energy X-ray absorptiometry provides a low-radiation alternative but cannot assess muscle quality. Bioelectrical impedance analysis and ultrasound are portable and inexpensive, yet lack standardized COPD-specific cut-offs. Functional tests provide clinically meaningful performance data but do not directly measure muscle mass. In parallel, nutritional screening tools and dietary assessment can identify modifiable risk factors and are associated with sarcopenia prevalence and prognosis in COPD. The choice of diagnostic approach significantly influences prevalence estimates. Conclusions: Optimal assessment of muscle wasting in COPD requires a multimodal approach combining muscle mass quantification, strength measurement, physical performance evaluation, and nutritional assessment. Standardized COPD-specific diagnostic criteria are needed. A practical algorithm integrating simple screening tools with targeted confirmatory assessments, including nutritional evaluation, may help guide clinical practice.