Restrained eating behavior and the metabolic response to dietary energy restriction in women

Objective: To determine whether prior eating behavior characterized by dietary restraint alters responses in energy expenditure and substrate oxidation associated with a short-term, energy-restricted diet. Research Methods and Procedures: A repeated-measures, 3-day diet-intervention study of adequate (125 kJ/kg of body, weight) or restricted (62.5 kJ/kg) energy intake was conducted with 30 women, 20 to 46 years, BMI 25 to 45 kg/m², whose prior eating behavior was "restrained" or "unrestrained." The Eating Inventory (cognitive restraint subscale) was used to measure restrained eating behavior. Energy expenditure and substrate oxidation were measured after a 12-hour fast and during the first and fourth hours after a standard meal. Plasma glucose, nonesterified fatty acids, and insulin were measured at corresponding times. Body composition was determined by total body electrical conductivity. Results: Resting energy expenditure was not affected by 3 days of energy restriction. Short-term energy restriction resulted in lower respiratory-exchange ratios, higher rates of fat oxidation, and lower rates of carbohydrate oxidation. Subjects classified as restrained eaters had higher postprandial respiratory-exchange ratios and carbohydrate-oxidation rates compared with unrestrained eaters. Fasting insulin concentrations were lower in restrained eaters. These effects associated with prior eating behavior were independent of the diet intervention. Discussion: Metabolic outcomes associated with a 3-day energy-restricted diet (i.e., increased fat oxidation and decreased carbohydrate oxidation) were not affected by prior restrained eating behavior. However, restrained eating behavior was associated with increased carbohydrate oxidation after a mixed meal. This effect of restrained eating behavior may be attributable to increased insulin sensitivity.