UBC Theses and Dissertations
Cognitive dietary restraint and factors related to bone mineral density and body weight in postmenopausal women Rideout, Candice AnnMarie
Cognitive dietary restraint (ongoing effort to limit dietary intake to manage body weight) is common in young women and has been associated with increased cortisol excretion and reduced bone mineral content (BMC). However, little is known about dietary restraint and its possible association with health in older women. This research addressed this gap by exploring cognitive dietary restraint in postmenopausal women aged 45-75 years. A broad survey of 1071 women assessed dietary restraint and other characteristics, and 78 respondents with high or low dietary restraint were recruited to complete measures of cortisol excretion, perceived stress, dietary intake, lifetime physical activity, and body composition. Study 1 examined cortisol excretion and body composition in women with high (n=41) versus low (n=37) dietary restraint. Groups were similar in age, body mass index (BMI), waist-to-hip ratio, current exercise, energy intake, perceived stress, body fat, BMC, and bone mineral density (BMD). However, cortisol excretion was higher in the high restraint group (248.2 ± 61.7 nmol/day versus 204.3 ± 66.1 nmol/day, P=0.01). Lifetime physical activity and current BMD were investigated in those participants in Study 2. Teenage physical activity, but not activity during other age periods, predicted postmenopausal BMD at both the lumbar spine (R²=0.110, P=0.004) and mean proximal femora (ΔR²=0.106, P=0.002). In Study 3, dietary restraint and ’dieting’ were compared in the 1071 survey respondents. Controlling for dietary restraint, dieters had higher BMI than non-dieters (+4.1 kg/m²; 95% CI: 3.6, 4.6). Conversely, controlling for dieting status, restrained eaters had lower BMI than unrestrained eaters (-1.0 kg/m²; 95% CI: -1.6, -0.5). Additional differences in food choice motives and psychosocial characteristics indicate that dietary restraint and dieting are not analogous. Finally, in Study 4, eating attitudes and weight-related characteristics were explored in survey respondents grouped according to 10-year weight history (maintenance, loss, gain, cycling). Disinhibition of eating control was the strongest predictor of current BMI in each weight history group, accounting for 11-20% of the variance. Dietary restraint predicted BMI only among women who had experienced weight cycling. Together, these studies suggest subtle differences in eating and activity characteristics contribute to the health of postmenopausal women.
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