Background: dietary habits and physical activity (PA) patterns play a crucial role in the integral development of children and adolescents. Objective: to compare according PA frequency (i.e., 0,1,2,3 or 4 times / week) and weight status (i.e., normal weight, overweight and obesity), adherence to the Mediterranean diet (MD), body image dissatisfaction and the physical fitness related to health, and as second objective to determine the association between these variables. Methods: 481 schoolchildren, 166 women and 315 men aged between 8 and 15 years (12.10 ± 1.10 years) belonging to public schools of Temuco, Chile participated. They were classified in three groups according PA frequency: group 1, without PA; group 2, PA 1-2 times/week, and group 3, PA 3-4 times/week. Cardio respiratory fitness (CRF), standing jump long test (SJT), handgrip strength, adherence to MD and body image dissatisfaction were measured. Results: Schoolchildren with more days of PA / week reported higher adherence to MD (p = 0.020), VO2max (p < 0.001) and SJT (p < 0.001) than peers. Likewise, schoolchildren with normal weight show more adherence to MD (P <0.001) and lower body image dissatisfaction (p < 0.001). There is a positive association between PA with VO2MAX (B, 1.28, p < 0.001). The gender presented association with body image dissatisfaction (B, 25.51, p = 0.019). Conclusion: the schoolchildren with greater frequency of PA/week, presenting greater adherence to MD and better physical fitness related to health.