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

Background: Chronic dieting syndrome can have negative physiologic and psyc hological consequences. Metabolic differences between female chronic dieter s with normal and with low resting energy expenditures (REEs) have not been fully examined. Objective: To determine whether differences existed between 2 groups (n = 1 5/group) of female chronic dieters aged 21-49 y with either normal (greater than or equal to 100% of predicted) and with low (less than or equal to 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 f itness, physical activity, glucose and insulin responses, leptin and thyroi d 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 insul in response to a test meal, higher thyroxine and reverse triiodothyronine c oncentrations, and lower dietary restraint. Within both groups, leptin decr eased significantly from baseline to 2 h after an oral-glucose-tolerance te st. 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 ra tios of abdominal to gluteal body fat in the normal-REE group. Leptin respo nse appears to be due to normal diurnal variations in leptin production rat her than a direct response to food consumption. It appears that a normal RE E does not necessarily predict positive metabolic health among chronic diet ers.