Effects of limiting access to diets with different composition on binge-like eating
Lee, Harrison Sunjoon
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Binge Eating Disorder (BED) is a deadly, psychiatric condition which affects about 10 million people in the USA. It is characterized by discrete and recurrent binge eating episodes consisting of rapid consumption of excessive amounts of highly palatable, energy-dense food (e.g. rich in sugars and fats) within discrete periods of time. Our laboratory has been focusing on the understanding of the behavioral, metabolic, and neurobiological factors underlying BED, through the development of an animal model of binge-like eating. This model is based on a limited access schedule in which rats are exposed 1-hour/day to a high-sucrose diet (HSD) in operant conditioning self-administration boxes. However, the consummatory and metabolic outcomes of exposing rats to a high-fat diet (HFD) in the same procedure are unknown. The aim of this thesis was to test the consummatory and metabolic effects of 1-hour limited access to either a HSD or a HFD in an operant rat model of binge-like eating. For this purpose, female rats were subjects of the binge-like eating procedure by limiting access to a HSD, a HFD, or a standard Chow diet. Our results show that limiting access to either a HSD or a HFD promoted binge-like eating as compared to control Chow diet. HSD binge-like eating was based on a true increase in the amount of food consumed, that is, an increased eating rate. Such suggests increase in palatability and a decrease in the home-cage standard chow intake, likely due to a negative contrast effect. Conversely, binge-like eating of the high-fat diet resulted from passive energy consumption due to the high energy-density of the food. Also, HFD binge-like eating was accompanied by neither increased eating rate nor rejection of the home-cage chow. Moreover, while HSD rats consumed less energy than HFD rats, the former were more energy efficient and gained more body weight than the latter. These results provide information on how the quality of food can deeply influence the behavioral and metabolic outcomes of binge-like eating.