The present thesis consists of three parts.
In part one the accuracy of self-reported weight and -height of children are described, since these measures are needed to determine the weight status of the child.
The second part describes the associations between childhood weight status and the frequency and type of consultations at the general practice.
In the third part, the effect of a multidisciplinary intervention program as treatment of obesity is described and the physical activity behavior of normal-weight children and children with overweight are investigated in more depth.