Interactions of varying levels of dietary fat, carbohydrate, and fiber on food consumption and utilization, weight gain and fecal fat contents in female sprague-dawley rats

Abstract

The purpose of this study was to better define a nutritional regime for the DMBA-induced rat mammary tumor model for studying the interdependent effects of fats, carbohydrates, and fiber on mammary tumor development. Female Sprague-Dawley rats were administered ( ad libitum) a modified AIN-76A diet containing different ratios of dietary fat, carbohydrate, and fiber for 6 weeks. Food consumption was decreased in the higher fat groups, but the decrease did not compensate completely for the higher caloric density of the diets. Calorie consumption and body weight gain were greater in both the mid and high than in the low fat groups. Dietary fiber had only a marginally significant effect on food consumption but did decrease both calorie consumption and body weight gain in the high fat groups. There was no significant interaction between fat and fiber with respect to food or calorie consumption, but there was a marginally significant interaction between these two dietary components on body weight gain. Food utilization, with respect to weight gain, was increased by fat and decreased by fiber, with a significant antagonistic interaction between the two. Calorie utilization (g weight gain/100 kcal) was increased by increased fat but the effect of fiber was not significant. Dry fecal weight was increased by dietary fiber and decreased by dietary fat. The amount of fecal fat excreted was increased by dietary fiber but the effects of dietary fat on fecal fat excretion were inconsistent. The results indicate a complex interaction of dietary fat and fiber. Animals administered the low fat/high fiber diet consumed the least number of calories and thus would be the control group in a pair fed, isocaloric study.