The purpose of the present study was to better understand the role of sweet taste perception in dietary behavior and body weight in outbred Sprague-Dawley phenotypic obesity-prone and obesity-resistant rats by measuring sucrose taste sensitivity using a conditioned taste aversion paradigm. Rats were given a high fat diet for 2 weeks and were assigned as obesity-prone (P, upper tertile) or obesity-resistant (R, lower tertile) based on weight gain. Each group was then given either chow (C, 10% fat) or the high fat diet (F, 46% fat) for the remainder of the experiment (similar to 18 weeks) such that there were four groups - obesity-prone on chow (C-P), obesity-prone on high fat (H-P), obesity-resistant on chow (C-R), obesity resistant on high fat (H-R). The sucrose sensitivity of phenotypic obesity-prone rats is lower than that of obesity-resistant rats in either H-fed or C-fed group, and all H-fed rats were more sensitivity than their C-fed counterparts (H-P vs. C-P; H-R vs. C-R). Body weight gain and total calories intake of phenotypic obesity-prone rats are more than that of obesity-resistant rats. The results suggest that lower sucrose taste sensitivity may contribute to body weight gain and total calories intake of phenotypic obesity prone rats compared to obesity-resistant rats, and there is correlation between the change in the sweet taste threshold and diet treatment. (C) 2017 Elsevier Inc. All rights reserved.