TNF and sarcopenia: Creeping fat is a typical feature of CD,34 and is associated with disease severity of CD through activation of the immune response.35 Inflammatory cytokines could lead to protein degradation in muscles via decreasing the expression of insulin-like growth factor 1 and resistance to growth hormones of muscles, such as tumor necrosis factor α (TNF-α) and Interlukin-6.36 Sixty percent of IBD patients were reported to have vitamin D deficiency, especially in CD patients,37,38 and pediatric CD patients with vitamin D deficiency are prone to suffering from sarcopenia.39