Endocrine Abstracts

Introduction: Post-operative modification of the sense of smell has been suggested as contributing to the reduction in energy intake and weight loss achieved following bariatric surgery. The aim of our study was to determine the prevalence of smell changes and their impact on weight loss five years after sleeve gastrectomy.

Methods: This was a descriptive longitudinal study conducted at the obesity research unit of the National Institute of Nutrition in Tunis involving 30 obese patients who had undergone sleeve-gastrectomy with medical follow-up of at least 5 years. Changes in the sense of smell were assessed using the Tichansky "Taste and smell" questionnaire.

Results: The mean age of our patients was 43 ± 9.5 years. The average duration of obesity was 26.4 ± 7.71 years, with extremes varying from 15 to 40 years. Average weight decreased from 133.04 ±18.36 kg to 94.63 ± 19.81 kg after 5 years, corresponding to an average weight reduction of 28.8% (P<10^-3). The excess weight loss was 48.48 ± 22.72%. Mean body mass index decreased from 52.61 ± 10.07 kg/m² to 38.04 ± 9.26 kg/m² after 5 years, a reduction of 27.69% (P<10^-3). The majority of our patients (63%) reported a change in appetite after sleeve gastrectomy. This change was better than expected in 53% of patients. A change in the sense of smell 5 years after sleeve-gastrectomy was noted in 53% of patients and consisted of either an improvement (62%) or a different smell (38%). No patient had a total loss of smell. The majority of our patients (80%) confirmed that the olfactory component of food is important for food intake. According to twenty patients, the smell of food has a direct impact on food intake and weight loss. Two-thirds of the patients expected a better change in smell than that obtained after sleeve gastrectomy. Patients who had a change in their sense of smell had the greatest loss of excess weight at 2 years (P=0.04) and 5 years (P=0.001).

Conclusions: Following sleeve gastrectomy, circulating gut hormone levels are markedly altered and these changes are suggested to contribute to post-operative olfactory changes. Gut hormones are present in saliva and their cognate receptors are found on taste buds and olfactory neurons Hence, it is plausible that gut hormones mediate olfactory changes following bariatric surgery through weight-independent mechanisms.