The differential effects of high-fat and high-fructose diets on physiology and behavior in male rats.

OBJECTIVES: The purpose of the current study is to directly compare a diet high in fat with a diet high in fructose. This side-by-side comparison will allow us to determine the physiological and behavioral effects resulting from the consumption of a diet dominated by one macronutrient.

METHODS: Rats were fed pelletized food containing either 60% fat or 55% fructose diet, or control chow (5.8% kcal of fat, 44.3% kcal carb) for 9 weeks. Animals performed a classic Morris Water Maze (MWM) and a reversal MWM to assess spatial and working memory near the end of the feeding period. At termination, tissue samples were collected including trunk blood, livers, fat pads, and brain punches.

RESULTS: Animals maintained on the high-fat diet weighed more by the end of the feeding period, had a higher percent body weight change and had higher fat pad weight than the high-fructose and control group. The high-fructose group had higher serum insulin levels than the high-fat group and higher total triglycerides than control or high-fat groups. Additionally, the high-fructose group entered the target quadrant significantly less than high-fat fed animals in the reverse MWM task.

DISCUSSION: These data suggest that fat accumulation and weight gain are influenced by the high-fat component of the Western-style diet. However, insulin resistance and elevated serum triglycerides are impacted more by high levels of fructose in the diet. Comparative data between a high-fat and high-fructose diet in a single study are novel and shed light on two of the individual components of a Western-style diet.