Restrained eating and ovulatory disturbances: possible implications for bone health.

We assessed the relationship between dietary restraint and menstrual cycle characteristics in 27 ovulatory women, previous participants in a longitudinal study of spinal cancellous bone mineral density (BMD). Subjects completed the restraint scale of the Three Factor Eating Questionnaire, recorded basal temperature and exercise for at least three menstrual cycles, and completed a 3-d food record. Cycle lengths of women in the upper and lower tertiles of scores for restraint were similar [27.8 +/- 1.0 (mean +/- SE) vs 27.6 +/- 0.8 d], but luteal phase length was shorter in the former group (8.6 +/- 0.9 vs 10.8 +/- 0.5 d, P < 0.05). Age, body mass index, percent body fat, waist-hip ratio, reported energy intake, and activity were similar between groups. Because the previous longitudinal study found associations between ovulatory disturbances and bone loss, we assessed spinal BMD using dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). BMD of women in upper and lower restraint tertiles, respectively, did not differ: DXA, 1.15 +/- 0.05 vs 1.20 +/- 0.06 g/cm2; and QCT, 140 +/- 7 vs 133 +/- 7 mg/cm3. Additional prospective studies, however, appear warranted. In conclusion, this study's results provide evidence that high dietary restraint is associated with a shortened luteal phase length.