Effect of Type of Carbohydrate on Energy Metabolism and Body Composition of Rats Fed Low Protein Diets

The effects of using dextrin (autoclaved cornstarch) instead of sucrose in low protein diets were investigated in growing rats. Two experiments involving metabolism studies were carried out, and differences in body composition and energy balance were evaluated. Since rats that were fed dextrin had greater food and caloric intakes than those fed sucrose, the former animals were able to maintain equivalent growth rates at lower protein levels in the diet, but retained a greater proportion of the calorie intake as fat. At the same mean body weight, the rats fed dextrin retained significantly more fat and energy in the carcass, and less nitrogen and water than those fed sucrose. At the same protein level, the use of dextrin in the diet caused an increase in the proportion of metabolized energy which was retained in the carcass; but when equivalent growth rates were obtained by lowering the protein content of the dextrin diet, the same proportion of metabolized energy was retained with each dietary treatment. However, the actual values for metabolized energy and for energy retained were higher at the same body weight for the rats fed the low protein-dextrin diet than for those fed the higher protein-sucrose diet. It is concluded that the use of dextrin instead of sucrose as the dietary source of carbohydrate alters the mechanism of food intake control and also the subsequent utilization and metabolism of the ingested calories.