The eating disorder bulimia nervosa is characterized by alternating periods of strict dieting and overeating. Patients also report mood fluctuations, frequent eating related thoughts, fear of loss of control over eating, impairment of cognitive abilities such as concentration, and somatic complaints. The present study attempted to clarify to what extent these symptoms are consequences of the dieting behavior. Nine healthy young women, classified as unrestrained eaters, were set on a intermittent dieting schedule over 4 weeks. Four days each week (Tue, Wed, Thu, Fri) they had to reduce their intake below 600 kcal/day, the other 3 days they could eat without restrictions. Psychological variables were assessed by means of a standardized diary. Biological indices of starvation were also measured repeatedly. There was no substantial weight loss after the 4 weeks, although subjects had significantly increased levels of beta-hydroxybutyric acid during the dieting periods, and decreased levels of t3 after 2 weeks. The reported tendency to overeat and the actual calorie intake during the days of unlimited access to food showed a significant increase over the 4-week period. Eating-related thoughts, feelings of hunger, and fear of loss of control were significantly more frequent during periods of dieting, compared to days of normal eating. Subjects also reported worse mood, heightened irritability, difficulties concentrating, and increased fatigue. These results suggest that a substantial part of symptoms of bulimic patients might be associated with the frequent periods of an extremely restrained eating behavior.