We estimated the prevalence of underweight, overweight and obesity of children and adolescents from Castilla-La Mancha region (Spain), applying the new International Obesity Task Force (IOTF) 2012 criteria, and analysed differences in physical fitness components in relation to weight status. The sample was 2,330 schoolchildren aged 6-17 years. We measured height and weight, calculated body mass index (BMI) and assessed physical fitness using four tests included in the EUROFIT battery. Differences in physical fitness components across BMI categories, by sex, were calculated using ANOVA models. In children aged 6-11 years, 4.9 % were underweight, 26.7 % overweight and 11.0 % obese; in adolescents aged 12-17 years, 6.4 % were underweight, 16.7 % overweight and 5.8 % obese. Overall, overweight and obesity were associated with worse physical fitness but students in the underweight category did not score worse than their normal weight counterparts on fitness tests.
Conclusion: Childhood obesity in Spain remains a public health problem. Our results show low physical fitness levels in overweight/obese children and adolescents and low levels of handgrip strength in underweight adolescents compared with normal weight subjects. Exercise programmes must be tailored to the specific needs of the subjects according to the different weight status.