A national study in Switzerland in 2002 suggested nearly one in five schoolchildren was overweight. Since then, many programmes have been introduced in an attempt to control the problem. The aim of the present study was to determine the prevalence of childhood overweight in Switzerland five years later.

In both studies a cross-sectional, three-stage, probability-proportional-to-size cluster sampling of schools throughout Switzerland was used to obtain a representative sample of approximately 2500 children aged 6–13 years. Height and weight were measured and BMI calculated. The BMI references from the Centers for Disease Control and Prevention were used to determine the prevalences of underweight (<5th percentile), overweight (≥85th and <95th percentile) and obesity (≥95th percentile).

In 2007 the prevalences of underweight, overweight and obesity in boys were 3·5 %, 11·3 % and 5·4 %, respectively; in girls they were 2·6 %, 9·9 % and 3·2 %. Compared with 2002, there was a significant decrease in the prevalence of overweight in girls and of obesity in both genders. In contrast to 2002, where there were no differences, in 2007 the prevalence of paediatric obesity was significantly higher in communities with a population >100 000 compared with smaller communities (P < 0·05).

In summary, over the past 5 years, the prevalence of adiposity has decreased in Swiss children. These findings suggest that increased awareness combined with mainly school-based programmes aimed at physical activity and healthy nutrition may have helped to control this public health problem. Future monitoring in Switzerland will determine if these findings are sustained.