The objective was to examine the tracking of obesity from childhood to young adulthood in Slovenia. A subsample included 4833 children from the Slovenian national sample (n 21 777) who were included in the SLOFIT monitoring system from 1997 to 2008, with complete data at 7 years and 18 years. A 12-year prospective cohort study. Height, weight and triceps skinfold thickness (TSF) were measured at 7, 11, 14 and 18 years. The BMI cut-off points of the International Obesity Taskforce were used to identify excess weight and obesity. The survey was conducted in Slovenian primary and secondary schools from 1988 to 2008 but only the data from the measurements in 1997, 2001, 2004 and 2008 are presented. Height, weight and BMI at 18 years were well predicted from childhood and became more predictable with age, while TSF was not. Obese and overweight children had the greatest risk of becoming obese or overweight young adults. The history of their weight shows that 40.0 % of males and 48.6 % of females who were obese at 18 years had already been obese at 7 years. Overweight or obese Slovenian children are more likely to become overweight or obese adolescents and young adults than reported in other similar European and American studies, which indicates the need for early prevention and treatment of excess weight and obesity.
