Statistical analysis
All data were analyzed using SPSS 16 software (SPSS, Inc., Chicago, IL). The normal distribution of data was checked using Kolmogorov–Smirnov test and Q–Q plot. Data are presented as frequencies (percentage) for qualitative variables, mean (± SD) for normally distributed continuous data, or median (25th, 75th) for other variables. Within-group changes were assessed with the use of paired t test for normally distributed data, Chi-square test or Fisher's exact test for nominal variables, and Wilcoxon rank-sum test for other data. The between-group differences were assessed with the use of independent t test for normally distributed data, Chi-square test or Fisher's exact test for nominal variables, and Mann–Whitney U test for other data. Analysis of covariance (ACNOVA) (adjusted for baseline values) was used to detect any differences between the two groups at the end of the study. P-value < 0.05 was considered statistically significant. Sample size was calculated based alpha of 0.05, beta of 0.20 (power of 80%) and effect size of one unit. HOMA-IR was considered as a primary outcome variable. By considering 20% drop-out rate, in total, the sample size was estimated 30 subjects in each group