TNF and obesity due to melanocortin 4 receptor deficiency: Obesity is linked to chronic low-grade inflammation, as excess adipose tissue produces pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-6, contributing to immune dysregulation.65 A meta-analysis found an association of elevated body mass index (BMI) and CD (HR: 1.42; 95% CI, 1.18-1.71) but not UC (HR: 0.96; 95% CI, 0.80-1.14).66 Low BMI may also serve as an age-dependent risk factor for CD.