Effects of a 12-Week Bodyweight Circuit Training Program Combined with Green Tea Consumption on Insulin Resistance and Body Composition in Sedentary Overweight Adolescent Boys

Introduction: Insulin resistance (IR) during adolescence is closely associated with excess adiposity and low physical activity and increases future cardiometabolic risk. School-based exercise programs are scalable; however, evidence on whether green tea intake enhances exercise-related metabolic benefits in overweight adolescents is limited.
Objective: To investigate the effects of a 12-week bodyweight circuit training program, alone or combined with daily green tea consumption, on IR and body composition (BC) in sedentary overweight adolescent boys.
Method: In this three-arm randomized controlled trial, sedentary overweight boys (14–17 years; BMI-for-age 85th–94th percentile) were randomized to Exercise + Green Tea (EX+GT), Exercise only (EX), or Control (CON). Exercise groups completed a school-based bodyweight circuit program twice weekly (60 min/session) for 12 weeks. The EX+GT group consumed 2 cups/day of green tea. Fasting glucose and insulin were measured to calculate HOMA-IR. Secondary outcomes included body mass, BMI, waist circumference, waist-to-height ratio (WHtR), body fat percentage, and fat-free mass. Outcomes were assessed at baseline and post-intervention and analyzed using ANCOVA.
Results: A significant group effect was observed for HOMA-IR (p<0.001). HOMA-IR decreased in EX+GT (4.31±0.93 to 3.12±0.71) and EX (4.19±0.88 to 3.54±0.76), with minimal change in CON. EX+GT improved HOMA-IR more than EX (p=0.041). Significant group effects were also found for body mass, BMI, waist circumference, WHtR, and body fat percentage (all p<0.05), generally favoring EX+GT.
Conclusions: A brief twice-weekly school-based bodyweight circuit program improved IR and BC in overweight adolescent boys, with greater metabolic benefit when combined with daily green tea consumption.