Taste and odor preferences following Roux-en-Y surgery in humans

Abstract

It is well established that bariatric surgery, the most effective method to achieve long-term weight loss in obese subjects, reverses enhanced preference and intake of sweet/fatty foods. Although taste and odor preference changes following bariatric surgery have been previously described, their time course and relationship to weight loss remains an issue. The aim of this study was to determine the relationship between taste and odor preference changes and successful weight loss following bariatric surgery. A cross-sectional study was performed on 195 human subjects with body mass index (BMI) above 30 (at least class I obesity), who were scheduled to receive (n = 54) or had previously received (n = 141) Roux-en-Y gastric bypass (RYGB). A Self-Assessment Manikin test was used to measure each participant's affective reaction (ranging from pleasure to displeasure) to a variety of food-related and odor-related pictures. Results confirmed earlier reports about changes in sweet/fatty foods preference after surgery and revealed a shift in preference toward less calorie-dense foods. Relatedly, endorsements of "favorite" foods were mostly sweet/fatty foods in subjects awaiting surgery but were shifted toward more healthy choices, particularly vegetables, in subjects post-RYGB surgery. However, food preference ratings trended toward pre-surgical levels as the time since surgery increased. Answers to open-ended questions about why their diet changed post-surgery revealed that changes in cravings, rather than changes in taste per se, were the major factor. Surprisingly, patients rating a coffee taste as more pleasing after surgery had a lower post-surgical BMI. No associations of odors with change in BMI were apparent. Results showed that following bariatric surgery taste preferences are significantly altered and that these changes correlate with lowered BMI. However, these changes fade as time since surgery lengthens. These results may suggest diagnostic criteria to identify people at risk for less than optimal changes in BMI following bariatric surgery.

Fig 1. SAM rating guide.

Fig 2. Relationship between time since RYGB surgery and change (reduction) in BMI.

Results of a moving average of change in BMI across the sample. Each point was the average of 10 subjects; the average was then advanced by one subject and recalculated. The point at which the slope of this curve changed was at 12 months post-surgery.

Fig 3. Responses to open ended question about favorite foods prior to and after surgery.

Fig 4. Median preference ratings for all pictures representing taste and odor stimuli for those awaiting RYGB surgery and those who have had RYGB surgery.

A. Subjects who had RYGB surgery less than 12 months prior to the survey. B. Subjects who had RYGB surgery more than 12 months prior to the survey. **p < 0.01.