Introduction Several studies warn that overweight and obesity have become an epidemic with severe consequences in the population's health. The objective of the present study is to estimate the prevalence of overweight and obesity in Castile and Leon in a sample of children at 6, 11 and 14 years of age, to describe its evolution and its association with life habits and antecedents. Material and methods Observational study, retrospective cohort, performed by the pediatricians of the Health Sentinel Network. The study is part of a joint Project with the National Research Center on Human Evolution (CENIEH) in Burgos to know the pattern of growth and development of the child population of Castile and Leon. In 2012, a health examination and a retrospective collection were carried out based on the clinical history of a simple of 326 children, from the cohort was born in 1998. Results Following the WHO references, at age 14 there was 25.3% of boys and 18.5% of girls with overweight. Obesity was estimated to affect the 8.2% and 4.8% of them respectively. At 11 years of age there was the maximum of overweight in girls and of obesity in boys. At the urban-non urban environment, quantity and quality of sleep and the parents’ BMI have been some of the associated factors to weight level of the children. Discussion In Castile and Leon, as in other populations of our environment, there is a severe problem of overweight and obesity. For their control it is necessary to deepen understanding of lifestyles and antecedents related to the birth as well as to calculate the growth rate in the pediatric age.