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/m(2), 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.