Abstract
<title>Abstract</title> <p> <bold>Introduction:</bold> Bariatric surgery alters eating behavior through mechanisms beyond gastric restriction, yet whether olfactory hedonic perception undergoes selective postoperative reorganization independent of odor identification remains unknown. The objective of this study was to evaluate whether Roux-en-Y gastric bypass (RYGB) is associated with descriptor-specific changes in olfactory hedonic perception over six months compared with waiting-list controls. <bold>Methods:</bold> In this prospective controlled cohort study conducted at a tertiary academic medical center, adults with obesity undergoing RYGB or remaining on a surgical waiting list were assessed at baseline and 180 days using an olfactory perceptual fingerprint (OPF) protocol rating pleasantness, intensity, familiarity, edibility, and irritability across eight odorants. The primary endpoint was the group-by-time-by-descriptor interaction in a linear mixed-effects model adjusted for age, sex, baseline BMI, and education. <bold>Results:</bold> Of 77 enrolled participants (49 surgical, 28 control), 61 (40 surgical, 21 control) completed OPF assessments at baseline and 180 days (retention: 82% surgical, 75% control). The global mixed model revealed a significant group-by-time-by-descriptor interaction (F = 4.280, p = 0.002). In emmeans difference-in-differences contrasts, irritability showed the largest between-group divergence (+24.3; 95% CI, 15.5 to 33.1; FDR-adjusted p < 0.001). Edibility showed a nominal signal (+10.7; p_raw = 0.049, p_FDR = 0.123). Odor identification remained stable (UPSIT p = 0.161; Multiscent-20 p = 0.102). <bold>Conclusion:</bold> RYGB was associated with descriptor-specific hedonic divergence in olfactory perception without parallel changes in odor identification. These findings are consistent with sensory-affective remodeling after bariatric surgery. </p>