Oxidative stress plays a pathological role in the development of various diseases including obesity. Systemic oxidative stress results from an imbalance between oxidants derivatives production and antioxidants defenses. The present study aims to investigate the oxidative stress and antioxidant defense system status in obese rats feeding some selected food processing by-products applied in bread. Forty two (140±10g per each) were divided into two main groups, the first group (Group 1, 6 rats) still fed on basal diet and the other main group (36 rats) was feed with diet-induced obesity (DIO) for 8 weeks which classified into sex sub groups as follow: group (2), fed on DIO as a positive control; groups (3-7), fed on DIO containing 5 % potato peel powder (PPP), cauliflower leaves powder (CLP), red onion skin powder (ROSP), mango peel powder (MPP) and their mixture, respectively. At the end of the experiment (8 weeks), rats of the obese group recorded 148.70% of the normal group for the BW. Biochemical analysis data indicated that obesity induced a significant increased (p≤0.05) in plasma oxidants concentration (TBARS, 41.95%; NO 2 , 31.02% and NO2/NO3, 26.45%) and significant decreased (p≤0.05) in plasma non-enzymes antioxidant (GSH, 30.83% and GSSG, 11.27%), plasma antioxidant vitamins (vitamin A, 27.43%; vitamin C, 20.98% and vitamin E, 31.50%) as well as RBC's antioxidant enzymes (GSH-Px, 37.66%; GSH-Rd, 28.66%; CAT, 19.51% and SOD, 25.26%) as a percent of normal