Twenty-four 16 to 17 year-old grammar school girls completed daily dietary histories (for eight weeks), and recorded details of mood, appetite and menstrual cycle. Marked daily variation in energy intakes was noted: on average an individual's highest daily intake was nearly four times her lowest intake, one subject having a nearly tenfold difference. Fluctuations were not related to mood, suggesting that this has less influence on dietary patterns than is generally supposed. While sitting examinations, energy intake was reduced by an average of 11.85%. It was not significantly changed during a field trip or by menstruation. This study suggests that dietary patterns previously considered to be abnormal or unusual are exhibited by and firmly entrenched in normal school girls.