Metabolic assessment of female chronic dieters with either normal or low resting energy expenditures.

BACKGROUND Chronic dieting syndrome can have negative physiologic and psychological consequences. Metabolic differences between female chronic dieters with normal and with low resting energy expenditures (REEs) have not been fully examined. OBJECTIVE To determine whether differences existed between 2 groups (n = 15/group) of female chronic dieters aged 21-49 y with either normal (>/=100% of predicted) and with low (</=85% of predicted) REEs based on the equation of Mifflin et al. DESIGN The sample was a nonrandomized convenience sample and the 2 groups were compared in an observational study design. Body composition, aerobic fitness, physical activity, glucose and insulin responses, leptin and thyroid hormone status, dietary intake, and dietary restraint were measured. RESULTS Both groups were similar with respect to age, height, weight, and body mass index. The normal-REE group had a higher lean body mass and insulin response to a test meal, higher thyroxine and reverse triiodothyronine concentrations, and lower dietary restraint. Within both groups, leptin decreased significantly from baseline to 2 h after an oral-glucose-tolerance test. The groups did not differ significantly with respect to dietary intake, aerobic fitness, or physical activity. CONCLUSIONS Differences in insulin response were associated with higher ratios of abdominal to gluteal body fat in the normal-REE group. Leptin response appears to be due to normal diurnal variations in leptin production rather than a direct response to food consumption. It appears that a normal REE does not necessarily predict positive metabolic health among chronic dieters.