Childhood obesity and low fitness tracks into adulthood and carries significant co-morbidities. The investigators test the hypothesis that a multidisciplinary multilevel lifestyle intervention in preschool children in the French and German speaking part of Switzerland during one school-year results in a smaller increase in body mass index (BMI) and a larger increase in aerobic fitness.

We will assess the effect of this multidisciplinary intervention in a multicenter cluster randomized controlled trial including a total of 40 kindergarten classes in the French (canton Vaud) and in the German (canton St. Gallen) speaking part of Switzerland. Health promoters, trained in physical education, will receive further postgraduate training (in nutrition, education, psychology) and will then in reward teach several kindergarten teachers hands-on. These trained health promoters will intervene on the level of the kindergarten teacher, the parents, the local community and also on the level of the children following a professional pre-specified curriculum in the kindergarten that focuses primarily on physical activity, healthy nutrition, media use and sleep duration. The curriculum also includes information evenings, workshops and fun weekly homework packages. Special attention will be paid to establish a curriculum that reaches also socio-cultural high risk groups living in Switzerland. Measurements will be performed before and after the intervention.

Inclusion Criteria:

• Healthy kindergarten children

Exclusion Criteria:

• Children with severe chronic disease (restricting physical activity)