OBJECTIVE To investigate 1) differences in cardiometabolic risk and HOMA of insulin resistance (HOMA-IR) across BMI categories (underweight to morbid obesity), 2) whether fit children have lower cardiometabolic risk/HOMA-IR than unfit children in each BMI category, and 3) differences in cardiometabolic risk/HOMA-IR in normal-weight unfit children and obese fit children.

RESEARCH DESIGN AND METHODS A pooled study including cross-sectional data from three projects (n = 1,247 children aged 8–11 years). Cardiometabolic risk was assessed using the sum of the sex- and age-specific z scores for triglycerides, HDL cholesterol, glucose, and the average of systolic and diastolic blood pressure and HOMA-IR.

RESULTS A significant linear association was observed between the risk score and BMI categories (P trend ≤0.001), with every incremental rise in BMI category being associated with a 0.5 SD higher risk score (standardized β = 0.474, P < 0.001). A trend was found showing that as BMI categories rose, cardiorespiratory fitness (CRF) attenuated the risk score, with the biggest differences observed in the most obese children (−0.8 SD); however, this attenuation was significant only in mild obesity (−0.2 SD, P = 0.048). Normal-weight unfit children had a significantly lower risk score than obese fit children (P < 0.001); however, a significant reduction in the risk score was found in obese fit compared with unfit children (−0.4 SD, P = 0.027). Similar results were obtained for HOMA-IR.

CONCLUSIONS As BMI categories rose so did cardiometabolic risk and HOMA-IR, which highlights the need for obesity prevention/treatment programs in childhood. Furthermore, CRF may play an important role in lowering the risk of cardiometabolic diseases in obese children.