Cognitive dietary restraint is associated with higher urinary cortisol excretion in healthy premenopausal women

Background: Cognitive dietary restraint, assessed by the Three-Factor Eatin g Questionnaire restraint subscale, is associated with subclinical menstrua l cycle disturbances. This association may be mediated by stress-activated cortisol release. Objective: We assessed whether 24-h urinary cortisol excretion differs betw een women with high and low restraint scores. Design: Participants (aged 21.6 +/- 2.5 y; n = 62) with normal-length menst rual cycles and high (n = 33) or low (n = 29) restraint scores completed a questionnaire describing weight history, dietary practices, and exercise. C ortisol, calcium, and creatinine were measured in urine collected over 24 h on a day when all food and beverages were provided and measured. Previousl y, 3-d food records and anthropometric measurements were obtained. Results: Age, height, weight, body mass index, and length of menstrual cycl e were similar between groups. The reported amount of exercise was higher ( 3.4 +/- 1.7 compared with 2.2 +/- 1.8 h/wk; P < 0.05) and energy intakes (a ssessed from 3-d and 24-h food records) were lower in the high- than in the low-restraint group. Ratios of urinary cortisol (nmol) to creatinine (mmol ) were higher in the high-restraint than in the low-restraint group (42.9 /- 12.9 compared with 36.3 +/- 8.9; P < 0.05), whereas ratios of urinary ca lcium (mmol) to creatinine were lower (0.3 +/- 0.1 compared with 0.4 +/- 0. 2; P < 0.05) in the high-restraint group. Urinary cortisol was not associat ed with exercise, nutrient intakes, or anthropometric measurements. Conclusions: High dietary restraint scores are associated with urinary cort isol, a biological marker of stress, and high cortisol excretion may affect bone health. Our results suggest that further research is warranted to cla rify these associations and to determine whether they persist over time.