While levels of carbonylated proteins, MDA, and SOD enzyme activity did not present significant differences between groups (p ≥ 0.09), children with obesity had significantly higher serum enzyme activity of CAT and GPx than children with normal weight (mean differences: Cat = 0.06 mgprot, p = 3.0 × 10−3; GPx = 0.14 U/mL, p = 2.12 × 10−19). The gene discussed is SOD1; the disease is obesity due to melanocortin 4 receptor deficiency.