BACKGROUND AND OBJECTIVES: Pediatric obesity is associated with clustered cardiometabolic risk and the future incidence of cardiovascular disease. However, few studies have determined the effect of pediatric obesity in Asia, where obesity is less common than in Western countries. We aimed to clarify whether weight status including underweight and slightly overweight is associated with metabolic risk factors in Japanese adolescents. METHODS AND STUDY DESIGN: We performed a cross-sectional analysis of 2241 adolescents aged 13-14 years. Participants were classified as underweight, normal weight, slightly overweight, overweight, or obese according to the International Obesity Task Force. The clustered cardiometabolic risk (Z-CMR) was estimated by summing standardized sex-specific Z scores of mean arterial pressure (MAP), non-high-density lipoprotein cholesterol (non-HDLC), and HbA1c. RESULTS: Linear regression analysis showed that MAP, non-HDL-C, and Z-CMR were higher in the slightly overweight, overweight, and obese groups than in the normal weight group after adjusting for confounders. Compared with the normal weight group, the slightly overweight, overweight, and obese groups had higher prevalence of high BP [odds ratios (ORs): 1.38 (95% CI, 1.03, 1.85); 2.63 (1.77, 3.91); and 2.39 (1.57, 3.64), respectively]. Compared with the normal weight group, underweight boys, but not girls, had a lower prevalence of high Z-CMR [OR=0.20 (0.05, 0.84)]. CONCLUSIONS: Adolescents classified as slightly overweight had higher levels of BP, serum lipids, and clustered cardiometabolic risk than those classified as normal weight. This observation showed significant associations between weight status and cardiometabolic risk factors during adolescence even in East Asians.