Background: Adults with class II/III obesity [body mass index (in kg/m2) ≥35] may present with a phenotype characterized by low lean mass and excess fat mass, a condition known as sarcopenic obesity (SO). Little is known about the prevalence and relevance of SO in these individuals, primarily due to a lack of relevant diagnostic criteria.
Objective: Here, we explored the definition of SO based on physical function as an outcome of interest in adults with class II/III obesity and applied this definition to compare clinical characteristics between SO and non-SO patients.
Methods: In this cross-sectional analysis, patients' demographic, anthropometric, and biochemical characteristics, as well as comorbidities and physical activity levels, were collected at an obesity specialty clinic prior to any treatment. Body composition was assessed by dual-energy X-ray absorptiometry. Physical function was assessed by self-reported difficulties with activities of daily living (ADLs) from an 11-item questionnaire. Five SO definitions were tested against reported difficulty with ADLs with the use of receiver operating characteristic (ROC) analysis.
Results: A total of 120 subjects (86% women) aged 46 ± 11 y were included. Based on ROC analysis, SO was best defined by an appendicular skeletal mass (ASM)/weight x 100 (%) <19.35% for women and <24.33% for men, resulting in a prevalence of 25% (n = 30, women 22.3%, men 41.2%). SO was significantly associated with older age, higher waist circumference, higher triglycerides, greater use of antihypertensive medications, and lower physical activity.
Conclusions: In this sample of adults with class II/III obesity, difficulties with ADLs were best associated with measures of ASM in relation to total body weight. Patients identified with SO using this criterion presented with poorer clinical outcomes such as factors of elevated cardiometabolic risk.
Keywords: activities of daily living; appendicular skeletal mass; class II/III obesity; dual-energy X-ray absorptiometry; lean soft tissue; sarcopenia.