Aim: To observe the effect of calorie restriction on the formation of lipid peroxide (malondialdehyde/MDA) caused by free radicals and antioxidant level (glutathione/GSH) among healthy young males during Ramadan fasting.Subjects and Methods: Prospective self-controlled study was performed on 22 healthy men aged 20-25 years who were presumed to be undergoing the calorie restriction. Subjects were observed four times: day 7 prior to the Ramadan month, the 7lh and 21"' days of Ramadan and day 7 after Ramadan. All data are presented as mean averages (SEM); all statistical comparisons were made using Anova Repeated Measures and Pearson's bivariate correlation.Results: Caloric intake decreased by 22 - 25% and MDA decreased significantly (p- 0.002), while GSH levels increased significantly (p= 0.047). There was no correlation between calorie restriction and MDA levels (p= 0.27; r= 0.25), but calorie restriction and GSH were correlated (p= 0.049; r= -0.18).Conclusion: This study showed that calorie restriction during Ramadan fasting decreased MDA and raised plasma GSH levels.