The chronic dieting syndrome has been described as a situation in which a person is overly focused on dieting, but has nonpathological psychological function. At any given time, an estimated 50% of North American women are participating in some type of dieting behaviour. In this study, energy metabolism and lifestyle behaviours were investigated in 172 women who met the criteria for the chronic dieting syndrome. The following measurements describe the study participants (mean SD): height, 163.2 6.0 cm; weight, 80.3 16.3 kg; age, 39.4 7.0 years; resting energy expenditure (REE), 1352 196 kcal/day (92% of predicted). Frequently reported behaviours and attitudes included regular physical activity (73%) and dissatisfaction with body size and shape (78%). Those who started dieting at an early age (= 16 years, n = 90), which implies greater chronicity, were compared with those who started dieting later (> 16 years, n = 82) (p < 0.001). The two groups' metabolic and behavioural characteristics did not differ. Over 21 years, restrictive eating behaviours had become the norm for these women, in spite of limited success at weight loss. The REE appeared to be reduced in only a small subset.