The Impact of Metabolic and Bariatric Surgery on Nutritional Status and Sarcopenia: A Narrative Overview of Underlying Mechanisms, Clinical Implications, and Prevention Strategies.

Bariatric surgery is the most effective treatment for severe obesity, leading to significant and sustained weight loss and improvement in metabolic comorbidities. However, it is also associated with substantial changes in body composition and nutritional status, including the risk of sarcopenia and sarcopenic obesity. This review aims to summarize current evidence on the interplay between metabolic and bariatric surgery, nutritional alterations, and skeletal muscle health. The recent literature highlights a high and increasing prevalence of muscle loss after surgery, driven by reduced protein intake, micronutrient deficiencies, hormonal changes, and decreased mechanical loading. Despite these challenges, improvements in metabolic health and physical function are often observed, suggesting a complex relationship between muscle mass and functional outcomes. A multidisciplinary approach, including nutritional optimization and structured exercise interventions, is essential to mitigate muscle loss and function and improve long-term outcomes. Further research is needed to standardize diagnostic criteria and develop targeted strategies for prevention and management.