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

The purpose of this study was to better define a nutritional regime fo r the DMBA-induced rat mammary tumor model for studying the interdepen dent effects of fats, carbohydrates, and fiber on mammary tumor develo pment. Female Sprague-Dawley rats were administered (ad libitum) a mod ified AIN-76A diet containing different ratios of dietary fat, carbohy drate, and fiber for 6 weeks. Food consumption was decreased in the hi gher fat groups, but the decrease did not compensate completely for th e higher caloric density of the diets. Calorie consumption and body we ight gain were greater in both the mid and high than in the low fat gr oups. Dietary fiber had only a marginally significant effect on food c onsumption but did decrease both calorie consumption and body weight g ain in the high fat groups. There was no significant interaction betwe en fat and fiber with respect to food or calorie consumption, but ther e was a marginally significant interaction between these two dietary c omponents on body weight gain. Food utilization, with respect to weigh t gain, was increased by fat and decreased by fiber, with a significan t antagonistic interaction between the two. Calorie utilization (g wei ght gain/100 kcal) was increased by increased fat but the effect of fi ber was not significant. Dry fecal weight was increased by dietary fib er 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 interacti on of dietary fat and fiber. Animals administered the low fat/high fib er diet consumed the least number of calories and thus would be the co ntrol group in a pair fed, isocaloric study.