Individual differences in behavioral responses to palatable food or to CCK predict subsequent diet-induced obesity

OBJECTIVE: This study investigated whether individual differences in behavioral responses to palatable food and to the satiation signal cholecystokinin (CCK) in outbred chow-maintained Sprague Dawley rats enabled prediction of individual differences in weight gained after subsequent high-fat/high-sugar diet (HFHSD) maintenance. METHODS: Meal size, meal number and early dark cycle intake during initial HFHSD exposure were measured as was early dark cycle sucrose solution and chow intake, chow meal size and meal number, the intake suppressive effect of 0.5μg/kg CCK injection, and CCK-induced c-Fos activation in the nucleus tractus solitarius (NTS). Subsequently, rats were maintained on HFHSD for five weeks and weight gain determined. RESULTS: Rats that took larger and less frequent meals on the first day of HFHSD exposure, whose early dark cycle intake (HFHSD and sucrose) was larger during initial HFHSD exposure, gained more weight after HFHSD maintenance. Rats with lesser sucrose intake suppression in response to CCK gained more weight after HFHSD maintenance and also displayed reduced CCK-induced c-Fos activation in the NTS. CONCLUSIONS: Together, these data identify individual differences in behavioral responses to palatable food and to CCK as novel predictors of diet-induced obesity.