Does bariatric surgery change olfactory perception? Results of the early postoperative course

Changes of food preference toward foods with low caloric density have been demonstrated after bariatric surgery and may contribute to sustained body weight loss. It has been hypothesized that olfactory perception as an integral part of food selection might be altered after bariatric surgery.

Sniffin' Sticks® were used to investigate the olfactory perception of morbidly obese patients undergoing either Roux-en-Y gastric bypass (RYGB, n = 15) or sleeve gastrectomy (SG, n = 15) before 1, 6, 12, and 24 weeks after surgery. Obese patients without surgical intervention served as controls (CG, n = 12). Results are presented using the testing odor threshold, discrimination, and identification score (TDI; higher scores indicate better olfactory perception). Body weight loss was recorded.

Initial BMI of the SG group (56.04 ± 7.096 kg m(-2)) was higher compared to the BMI of the RYGB (48.71 ± 6.49 kg m(-2)) and CG (50.35 ± 6.78 kg m(-2)); p = 0.011. Body weight loss among the surgical groups was not different (p = 0.011) while controls did not lose weight. Mean baseline TDI scores were significantly lower in the SG group 27.1 ± 3.9 vs. 32.6 ± 3.6 (RYGB) and 32.1 ± 5.3 (CG), respectively, whereas there were after 24 weeks no changes in RYGB and CG patients; the TDI score in the SG group increased significantly to 31.1 ± 3.5 (p < 0.01).

Our data suggest that a substantial body weight loss per se does not affect olfactory perception. However, our results point towards improved olfactory perception after sleeve gastrectomy but not Roux-en-Y gastric bypass.