The goal of this observational study is to the purpose is to apply of ESPEN/EASO criteria for the diagnosis of sarcopenic obesity and calculation of OS prevalence in a sample of COPD patients. In addition, this study want to evaluate the impact of sarcopenic obesity on the respiratory function of COPD patients and the degree of severity of respiratory disease, assessed by spirometric examination; diaphragm thickness and excursion, by ultrasonographic study; performance, assessed by six-minute walk test (6-MWT); quality of life and degree of dyspnea (mMRC, Barthel dyspnea, S. George Respiratory Questionnaire); compliance and outcomes at the end of the respiratory rehabilitation course. Comparison with normal-weight patients with and without sarcopenia will help to better understand the clinical impact of sarcopenic obesity in this category of patients.