1. Does Scheduled Intermittent Access to a Highly Palatable Carbohydrate-Rich Food Trigger Binge Eating in Laboratory Rats? Robynn Mackechnie, Kishan Govind, and G.R. Davis, Department of Biology, Wofford College, Spartanburg, SC 29303 Binge eating is defined as eating a larger than normal amount of food in a distinct period of time. Corwin et al. (2003) showed that rats binge eat on Crisco ® (100% fat, 9.2 kcal/g) if the highly palatable food is offered 3 times per week. Here we replicate that study substituting a high carbohydrate food (Froot Loops ® ; 84% carbo- hydrate, 3% fat, 3% protein, 3.8kca/g.) The purpose of this study is to determine if intermittent access to a highly palatable carbohydrate-rich food, Froot Loops ®, triggers binge eating. Methods Introduction Summary Acknowledgements Results Scheduled regular and irregular intermittent access to highly palatable carbohydrate-rich food (Froot Loops ® ) triggers binge eating in laboratory rats. Hypothesis Subjects: Forty male Sprague-Dawley rats (Charles River), 81 days old, 368  18 g at the start of the study were housed individually in standard plastic shoebox cages with bedding on a 12:12 light:dark cycle (lights off at 4 pm.) Feeding schedule: Ad libitum commercial rodent chow (RC) (Harland Teklad 8604; 3.3 kcal/g) and tap water. Ad libitum access to Froot Loops (FL) from 2-4 pm according to a schedule (Table 1). FL were threaded onto Plexiglas ® rods placed on top of cages to ensure the modality of eating FL was similar to RC. Groups: Based on 24 hr FL intake and body weight, rats were assigned to four balanced groups of n=10 described in Table 1. Measurements: Body mass recorded twice weekly on M & Th. RC intake measured daily at 4 pm. FL intake measured for 2 hr period (2-4 pm.) Food intake represented in kcal. Statistics: Differences were analyzed using one way ANOVA, Student- Newman-Keuls post hoc testing. A p-value of < 0.05 was considered significant. Status of Hypothesis Discussion FIGURE 1: Caloric intake of RC and FL for 24 hr. periods. Graph A: R7 caloric intake does not differ significantly on any day from C. Graphs B & C: R3 and I groups matched caloric intake of C when FL were available but consumed fewer calories on days when FL were not available. In bottom graph “+” indicates days in which FL were available to I group. “ * ” indicates significant differences (p < 0.5). FIGURE 2: 2 hour intake on Day 28: By the end of the 4 weeks, patterns of FL intake had stabilized for each group. When FL were available, R7, R3, and I rats ate large amounts (~25kcal) relative to Control animals which consumed ~5kcal of chow during the 2 hr interval. Rats with access to FL reduced their intake of chow during the 2 hour period. FIGURE 3: Body Mass: All groups of rats gained weight throughout the 28 day experiment. However, on day 27, R3 and I rats weighed less than the C and R7 rats. * = different from C.. FIGURE 4: Cumulative Caloric Intake: R3 and I consumed fewer calories than R7 and C animals over 28 experimental days. * = different from C. Scheduled regular and irregular intermittent access to a highly palatable food that consists primarily of carbohydrates did not trigger binge eating..  The R7 caloric intake was no more than C on any day suggesting that rats do not over-eat or under-eat when a highly palatable food is available daily.  Rats compensate for intake of highly palatable food by reducing intake of chow. This shows that laboratory rats exhibit remarkable daily caloric intake regulation.  One might expect that rats with access to FL would gain weight at a faster rate than C animals. They did not. Rats exposed to FL may have anticipated or expected FL and reduced RC intake and thereby consume fewer calories on days when FL were not available.  Under-eating on multiple days explains why R3 and I rats weighed less at the conclusion of the study. There was a direct correlation between the body mass and 28 day cumulative caloric intake.  In this study, rats did not consume extra calories when provided highly palatable foods, thus behaving quite differently from humans under similar circumstances. At least in this respect, rats are not an ideal model for human feeding behaviors.  The working definition of binge eating is the consumption of a larger than normal amount of food in a short time. Food intake may be expressed in terms of volume (ml) or mass (g) or energy (kcal.) On a per gram basis, Crisco ® (100%) fat has 2.4 times the caloric content of Froot Loops ®. Thus, relatively small increases in the consumption of an energy dense food would result in large increases in energy intake which could be interpreted as binge eating.  Corwin (2003) reported that intermittent access to 100% fat triggered episodes of binge eating. Using an identical protocol, we find that rats do not binge eat on Froot Loops ®. This suggests that the propensity to binge eat depends at least in part on the nature of the palatable food provided. Results continued Support was provided by a Fullerton Foundation grant which funds student-faculty collaborations in the Community of Scholars summer research program at Wofford College. We found no clear evidence of binge eating. Rats given FL every day (R7) did not weigh more than control rats maintained exclusively on rodent chow. Surprisingly, rats given intermittent access to FL on an irregular schedule (I) or 3 days per week (R3) cumulatively consumed fewer calories and gained less weight than other groups of rats. A B C Schedule for Access to FL Day of WeekSSMTWThFSSMTW FSSMTW FSSMTW F Experiment Day12345678910111213141516171819202122232425262728 Control (No Access) C Regular Access 7d/wk R7 Regular Access 3d/wk R3 Irregular Access (12x total) I