Metabolic dysfunction-associated hepatic steatosis (MAFLD) indicates the metabolic risk associated with hepatic steatosis, overweight and obesity, and clinical evidence of metabolic dysregulation. Since MAFLD is one of the diseases that show a high frequency of alterations in the lipid content of cell membranes, the aim of this study was to evaluate the indices of oxidative damage of erythrocyte membranes in overweight and obese MAFLD subjects. The study was conducted on serum samples and red blood cell membranes of overweight and obese MAFLD subjects. For each patient, biochemical measurements and lipidomic analyses of erythrocytes membranes were performed. Significant differences in fatty acid profiles of RBC membranes were found between overweight and obese patients. In particular, the Peroxidation Index (PI) was higher in the erythrocyte membranes of obese subjects than in overweight subjects. The same behavior was observed for Unsaturation Index (UI) and Free Radical Stress Index (Free RSI), supporting the fact that the systemic increase in oxidative stress was associated with obesity. The study shows that there is a different susceptibility to erythrocyte membrane peroxidation for overweight and obese subjects, and the increased values of oxidative stress indices observed in the erythrocyte membranes of obese patients with MAFLD may be a possible indicator of pro-oxidative events occurring in obesity-related diseases.