School-based PA interventions have a significant effect size (ES) in reducing body fat percentage (ES = −0.43, p < 0.01), diastolic blood pressure (ES = −0.27, p < 0.05), triglycerides (ES = −0.38, p < 0.01), fasting blood glucose (ES = −0.60, p < 0.01), blood insulin (ES = −0.62, p < 0.01), and homeostatic model assessment-insulin resistance (ES = −0.58, p < 0.01) in overweight or obese students. The gene discussed is INS; the disease is Insulin resistance.