ASSOCIATIONS AMONG COGNITIVE DIETARY RESTRAINT, EXERCISE AND BONE STATUS IN YOUNG WOMEN

Abstract

1415 High levels of cognitive dietary restraint (conscious limitation of food intake to regulate body weight) are associated with ovulatory disturbances, which in turn have been linked to bone loss. This study assessed whether restraint was associated with bone status in young women who reported exercising minimally (<2hrs/wk) or moderately (2-7 hrs/wk). Sixty-one women, 21.6 ± 2.5 yrs old, with high (n=32) or low (n=29) restraint levels completed this cross-sectional study. All reported regular menstrual cycles. Body composition and bone were assessed by DEXA, exercise level by questionnaire, and cortisol by 24-hr urine collection. Women with high and low restraint did not differ in age, ht, wt, fat mass or non-bone lean tissue, although those with high restraint exercised more (3.4 ± 1.7 vs 2.2 ± 1.8 hr/wk; p<0.05) and had higher cortisol/creatinine (42.92 ± 12.92 vs 36.34 ± 8.90; p<0.05). Compared to women who exercised minimally (n=20), those exercising moderately (n=41) had significantly higher whole body bone mineral density (BMD) and content (BMC), and spinal BMD. Among moderate exercisers (n=41), whole body BMC (2553.86 ± 301.64 g vs 2315.30 ± 263.65 g; p<.05) and spinal BMC (65.61 ± 11.21 vs 55.73 ± 14.13 g; p<.05) were higher in women with low than with high restraint, and the difference in spinal BMD approached significance (1.224 ± .150 vs 1.146 ± .097 g/cm2; p=.061). Although several variables correlated with whole body BMC, after controlling for weight, only restraint level and cortisol/creatinine were significant predictors in multiple regression analysis. Whole body BMD, spinal BMD and BMC were predicted only by restraint. These results suggest that high dietary restraint may offset some of the benefits of exercise on bone. The inverse relationship between dietary restraint and bone status may be associated in part with higher cortisol levels, which are known to impact negatively on bone.