The present study aimed to investigate the effect of a six-week metabolic conditioning training program on serum levels of insulin-like growth factor-1 (IGF-1) and glutathione peroxidase (GPX) in physically active young adults. This randomized controlled trial employed a pre-test–post-test design with a control group. A total of 23 physical education students (aged 18–24 years) were purposively recruited and randomly assigned to an exercise group (n = 12) or a control group (n = 11). The exercise group participated in a six-week metabolic conditioning circuit training program (three sessions per week, 18 sessions total), with progressive overload in volume and intensity. The primary between-group analysis using ANCOVA, after adjusting for baseline values, revealed no statistically significant difference between the groups in post-test IGF-1 levels (F(1,20) = 1.339, p = 0.261, η² = 0.063) or in post-test GPX levels (F(1,20) = 0.682, p = 0.419, η² = 0.033). A secondary within-group analysis showed a significant decrease in IGF-1 within the exercise group (p = 0.047); however, this finding must be interpreted with caution given the negative primary between-group comparison. No significant within-group changes were observed for GPX (p > 0.05). Anthropometric measures (weight and BMI) remained stable in both groups throughout the study. Based on the primary between-group comparisons, these findings indicate that six weeks of metabolic conditioning does not produce statistically significant changes in serum IGF-1 or GPX levels compared to a control condition in physically active young adults. Further research with larger sample sizes and longer intervention periods is warranted.