Abstract： Objective To explore the effects of diet and/or exercise intervention on oxidative stress of overweight or obese adolescents.Methods Thirty-one adolescents with normal body weight(normal control group)and 93 overweight or obese adolescents(average age(13.6 ±0.7)years; body mass index (BMI)22.4 to 34.1 kg/m2)were enrolled in this study.The overweight or obese participants were then randomly assigned to the diet group(group A),exercise group(group B),diet plus exercise group(group C),and non-intervention group(group D).Individualized caloric intake was carried out.One-hour afterschool exercise was performed once per day,4 days per week for 10 weeks.Changes of anthropometry,body composition,and metabolic biomarkers were determined.Results Compared to the normal control group,serum levels of fasting glucose,total cholesterol(TC),low-density lipoprotein cholesterol(LDL-C),and malondialdehyde(M DA)of the in overweight group were significant increased(all P ＜ 0.05),although the level of SOD was significant decreased(P ＜ 0.05).Serum MDA level was positively correlated with bodyweight,BMI,TC,and LDL-C(R values were 0.209,0.228,0.274,and 0.263,respectively ; all P ＜0.05),and serum SOD level was negatively correlated with bodyweight and BMI(R values were-0.334 and-0.362,respectively ; both P ＜ 0.05).Group A,B and C showed a significant decrease in BMI,waist circumference and body fat after the intervention(all P ＜ 0.05).The level of MDA was significantly decreased after the intervention in group A and B(both P ＜ 0.05); the levels of TC and LDL-C were significantly decreased in group B and C(both P ＜ 0.05).Conclusion:Oxidative stress could have existed in overweight adolescents even when their serum glucose and lipid profiles are at a normal level.Ten-week diet and/or exercise intervention may contribute to improved body weight control,lipid metabolism,and oxidative stress response in this population.