BACKGROUND: The interaction between motivation to eat, eating behavior traits, and gut peptides after Roux-en-Y gastric bypass (RYGB) surgery is not fully understood. METHODS: Appetite and hormone responses to a fixed liquid preload were assessed in 12 obese (body mass index 45±1.9 kg/m(2)) participants immediately before and 3 days, 2 months, and 1 year after RYGB surgery. Subjective appetite and plasma levels of ghrelin, leptin, insulin, and glucagon-like peptide-1 (GLP-1) were measured for a 3-hour postprandial period. Eating behavior traits were also measured using the Three Factor Eating Questionnaire 18 (TFEQR18). RESULTS: There was a decrease in TFEQR18 emotional eating (EE) and uncontrolled eating (UE) from presurgery to 1 year postsurgery but no significant change in cognitive restraint (CR). These changes occurred independently of change in weight. In addition, there was a reduction in subjective appetite ratings and alterations in appetite peptides favoring an anorectic response. Presurgery EE was significantly related to fasting and area under the curve (AUC) ghrelin; UE was associated with AUC desire to eat, and there was a significant association between fasting desire to eat and ghrelin (fasting and AUC). One year postsurgery, UE was positively related to fasting insulin, and CR was negatively associated with GLP-1. UE and subjective hunger were positively correlated, while the relationship between desire to eat and ghrelin remained. CONCLUSION: The relationships among subjective appetite ratings, eating behavior traits, and appetite peptides in obese patients both before and at 1 year after RYGB surgery may contribute to the reduction in a propensity to overeat (as measured by TFEQR18 factors) and weight loss.