Impact of Weight Loss on Olfaction in Patients Undergoing Bariatric Surgery

Olfaction plays a vital role in regulating nutrition, avoiding potentially dangerous situations, and modulating behavior along with interpersonal relationships. Many common disorders can have a negative impact on olfaction; one of these is obesity. Bariatric surgery induces weight loss, and current evidence suggests that it can cause improvement in olfaction. However, more information is needed regarding this topic.

One hundred eighty-five patients who underwent bariatric surgery and 184 age- and gender-matched control group who did not undergo any surgery have completed a questionnaire including items from the validated Self-Reported Mini Olfactory Questionnaire.

Final analysis was based on 369 patients. There was a statistically significant difference between patients before and after surgery (p < 0.05). However, there was a statistically significant difference between people who underwent surgery with < 50% excess body weight loss and the control group but none with those > 50% excess body weight loss. No significant differences were found when comparing people with and without chronic illnesses, head and neck surgery, anti-allergy drug use, and COVID-19. Before surgery, there were statistically significant differences between patients with allergic rhinitis and polyps and those without, but no significant differences were observed after surgery.

Patients had significantly improved olfactory scores post-surgery compared to before surgery. Patients who had > 50% excess body weight loss after surgery showed olfactory function as good as the general population represented by the control group. However, those with < 50% excess body weight loss had significantly worse olfactory scores compared to the general population.