Changes in appetite, taste and smell are par for the course for people who have undergone Roux-en-Y gastric bypass surgery during which one's stomach is made smaller and small intestines shortened. These sensory changes are not all negative, and could lead to more weight loss among patients, says Lisa Graham, lead author of a study by researchers from Leicester Royal Infirmary in the UK. Their findings, published in Springer's journal Obesity Surgery showed that after gastric bypass surgery, patients frequently report sensory changes.
Graham and her colleagues say their day-to-day experience with patients who have undergone gastric bypass surgery suggested these changes, but surprisingly little has yet been written about it in scientific literature. To this end, questionnaires were sent out to patients who had undergone the procedure at the University Hospitals of Leicester between 2000 and 2011. In total, 103 patients answered the 33 questions about appetite, taste and smell set to them.
Of the respondents, almost all (97 percent) reported changes to their appetite after having the surgery. Their experiences varied, with subjects reporting that their sense of smell and taste were either unchanged, heightened or reduced. Forty-two percent of respondents said their sense of smell changed. Seventy-three percent of patients noted change in the way food tasted, and especially in their sweet and sour palate. Respondents especially noted a change in the taste of chicken, beef, pork, roast meat, lamb or sausages, while fish, fast foods, chocolate, greasy foods, pasta and rice were also high on the list.
Three out of every four (73 percent) patients noted that they had developed an aversion to specific foods after the surgery. Meat products topped the list, with one in every three patients steering away from chicken, minced beef, beef steak, sausages, lamb, ham or bacon. Starches such as pasta, rice, bread and pastry and dairy products such as cream, ice cream, cheese and eggs were a no-no for almost 12 percent of respondents. Only 4 percent of respondents reported having an aversion for vegetables, 3 percent for fruit, and 1 percent for tinned fish.
Interestingly, patients who experienced food aversions enjoyed significantly more postoperative weight loss and reduction in their body mass index (BMI) compared to their counterparts without such dislikes. They typically experienced weight loss of around 8 kilograms and a loss of BMI of 3 kg/m2 greater than their counterparts.
It is still unclear what the role is that perceptual changes in the taste and smell of food play to influence calorie intake, meal composition and subsequent weight loss following bariatric surgery. However, Graham believes the sensory changes are due to a combination of gut hormone and central nervous system effects.
"This study indicates that subjective changes in appetite, taste and smell are very common after Roux-en-Y gastric bypass," Graham summarizes the findings of the study, which are in line with that of other ones done. Patients are routinely counselled about the potential loss of taste and smell in consenting for surgery.
Graham, L. et al (2014). Taste, Smell and Appetite Change After Roux-en-Y Gastric Bypass Surgery, Obesity Surgery, DOI: 10.1007/s11695-014-1221-2