Author
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Keim, Nancy |
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Horn, William |
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Submitted to: Obesity Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/18/2003 Publication Date: 1/1/2004 Citation: Keim, N.L., Horn, W.F. 2004. Restrained eating behavior and the metabolic response to dietary energy restriction in women. Obesity Research. 12(1), 2004. Interpretive Summary: Previous studies have found that there are considerable differences in the individual¿s metabolic response to a calorie-restricted diet, with some people reducing their use of energy more than others. This suggests that one individual¿s ability to conserve energy varies a lot from another¿s, which, in turn, could affect the amount of weight loss that can be achieved with such diets. We proposed that some of this variation in response to restrictive dieting might be the result of an individual¿s past eating behavior. There is a belief that people who purposely reduce their food intake to avoid weight gain become more efficient in adjusting their metabolism in response to restrictive dieting, and therefore may experience more difficulty in losing weight or more ease in regaining lost weight. We found that women who possess restrained eating behavior responded to short-term dieting in a fashion similar to women who were not restrained eaters. However, after eating a mixed meal, restrained eaters favored the use of carbohydrate for energy. We conclude that restrained eating behavior does not appear to alter the total calories burned, but does affect the preferred source of calories used following meal ingestion. This finding may be indicative of a metabolism that favors storage of fat and contributes to the ease of weight gain. Technical Abstract: This study was conducted to determine if restrained eating behavior alters the responses in energy expenditure and substrate oxidation associated with a short-term restricted diet. A repeated measures, 3-d diet intervention study of adequate (125 kJ/kg body weight) or restricted (62.5 kJ/kg body weight) energy intake was conducted with 30 women, 20-46 y, BMI 25-45 kg/m2, who were restrained or unrestrained eaters. The Eating Inventory was used to measure dietary restraint. Energy expenditure and substrate oxidation were measured after a 12-h fast and during the 1st and 4th h following a standard test meal. Plasma glucose, non-esterified fatty acids, and insulin were measured at corresponding times by standard techniques. Body composition was determined by total body electrical conductivity. Resting energy expenditure was not affected by 3-d of energy restriction. Short-term energy restriction resulted in higher respiratory exchange ratios (RER), higher fat oxidation and lower carbohydrate oxidation. The restrained eaters had higher postprandial RERs and carbohydrate oxidation rates compared to the unrestrained eaters. Fasting insulin concentrations were lower in restrained eaters. All dietary restraint effects were independent of diet intervention. The metabolic outcomes associated with a short bout of restrictive dieting, increased fat oxidation and decreased carbohydrate oxidation, were not altered by dietary restraint. The main effect of dietary restraint was to increase carbohydrate oxidation following a mixed meal. This effect of restraint may be attributable to increased insulin sensitivity. |
