1. Longitudinal changes in nutritional habits were studied in Dutch adolescents from 12 to 17 years of age (131 girls and 102 boys). The dietary differences on schooldays and weekend days are reported.
2. In girls only small changes in nutritional habits were seen as they grew older. In boys there was a gradual increase in food intake with age.
3. Overall, higher nutrient intakes could be seen on weekend days. The energy intake on weekend days was consistently higher for girls and boys in all age-groups. The proportional intakes of fat and sugar were rather high, especially on weekend days. The alcohol consumption increased with age for girls as well as boys, and was for some individuals extremely high (boys) on weekend days.
4. The observed levels of intake compared with the recommendations showed a rather low intake of polyunsaturated fatty acids, polysaccharides and iron.