Changes in appetite after bypass aids weight loss

It has been known for some time that changes in appetite, taste and smell are par for the course for people who have undergone Roux-en-Y gastric bypass surgery however, a UK study has found that patients who experienced food aversions enjoyed significantly more postoperative weight loss and reduction in their BMI compared to their counterparts without such dislikes.

The study by researchers from Leicester Royal Infirmary, UK, stated that patients frequently report sensory changes after gastric bypass surgery and these changes could lead to further weight loss.

The paper, published in the journal Obesity Surgery, indicates that subjective changes in appetite, taste and smell are very common after Roux-en-Y gastric bypass, and patients should be routinely counselled about these changes as part of the informed consent process for surgery.

It is apparent from day-to-day practice that patients frequently report changes to their appetite, taste and smell after weight loss surgery. There has been surprisingly little written in the literature on this. The aim of the study was to assess these parameters in a cohort of patients undergoing Roux-en-Y gastric bypass surgery.

The research team sent questionnaires 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 and 73 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 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, the researchers believe the sensory changes are due to a combination of gut hormone and central nervous system effects.