Flavor-calorie relationships: effect on weight gain in rats

The effects of flavor variety, caloric density variety, and inconsistency of flavor-caloric density relationships on caloric intake and weight gain were studied in 36 young male rats. Lab chow was diluted with cellulose to produce three foods that differed in caloric density while having identical nutritional composition. High-density (HD) food contained 3.33 kcal/g; mid-density (MD) food contained 2.64 kcal/g; low-density (LD) food contained 2.06 kcal/g. These foods were flavored with nonnutritive powders and were used in four different feeding regimens. For 15 days, group FLAV ate MD with one of 3 flavors added daily in a 3-day rotation. Groups DENS and NOVEL rotated daily among LD, HD, and MD. One of three flavors was added to each food. For group DENS, LD always contained one flavor, MD always contained another flavor, and HD always contained the third flavor. For group NOVEL, flavor-density pairings were not consistent. A control group, CONT, ate only MD with a single flavor. Weight gain was greatest in group NOVEL. Neither density variety nor flavor variety alone enhanced weight gain relative to control. In a subsequent experiment, group NOVEL did not display a preference for a glucose-paired flavor. These results suggest that reduced orosensory control of energy balance induced by uncoupling of flavor-calorie relationships contributes to weight gain.