Abstract
OBJECTIVE: Sleeve gastrectomy (SG) effectively reduces food intake and enhances health and longevity, although weight loss often involves reductions in body fat and skeletal muscle. Hence, we examined how changes in skeletal muscle density relate to muscle strength and physical activity before and after SG. METHODS: This pilot observational study included 173 patients (mean age: 46 ± 11 years) who attended the hospital before and 1 year after undergoing SG between December 2018 and July 2022. Muscle cross-sectional area (cm(2)), skeletal muscle density, and fat cross-sectional area (cm(2)) at the 3rd lumbar vertebra were measured on computed tomography (CT) images. The psoas muscle index (PMI) was calculated as the cross-sectional area of both psoas muscles (cm(2)) divided by height squared (m(2)), and CT values for skeletal muscle density of the psoas and multifidus muscles, visceral fat area (VFA), and subcutaneous fat area (SFA) were obtained. Relative and absolute muscle strengths, sitting time, and total physical activity from the International Physical Activity Questionnaire were also assessed. RESULTS: Although VFA, SFA, PMI, and absolute muscle strength decreased significantly after SG compared to those before SG (p <0.001), skeletal muscle density, relative muscle strength, and total physical activity increased significantly after SG, with a significant reduction in sitting time (p <0.001). There were significant positive correlations between changes in skeletal muscle density and changes in relative muscle strength and total physical activity. CONCLUSIONS: Improving skeletal muscle density with SG may be associated with increased relative muscle strength and improved physical activity.