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Change in appetite, taste, smell expected with gastric bypass contributes to weight loss
Patients who have recently undergone gastric bypass surgery can anticipate changes in their appetite, as well as the taste and smell of food, according to findings published in Obesity Surgery.
Lisa Graham, RN, and colleagues from the Leicester Royal Infirmary in the United Kingdom collected responses to 33 questions from 103 patients (14 men, 89 women; mean age, 45 years) who had Roux-en-Y surgery at the institution from 2000 to 2011. Patients’ BMI ranged from 36 to 97, with a median of 51.
Respondents reported changes —heightened or reduced — in appetite (97%), taste (73%) and smell (42%). Aversion to specific foods after surgery was reported by 73% of patients, especially in their sweet and sour palate. Meat products were cited most often (33%), followed by starch (12%).
Patients who reported food aversions achieved significantly greater postoperative weight loss compared with those who did not report food aversions, with a median weight loss of 8 kg and BMI loss of 3 kg/m² greater than their counterparts.
The role of perceptual changes in appetite, taste and smell of food in influencing caloric intake, meal composition and weight loss after surgery remains unclear. But the researchers concluded it is “multifaceted and includes physical factors, gut neuroendocrine actions and central nervous system effects.”
“In the longer term, being able to harness the food aversions (with the better weight loss achieved in these patients) is an avenue to explore to try and maximize the benefits of weight loss surgery,” David Bowrey, MD, told Endocrine Today.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Weight loss surgery used to be seen as “enforcing a good diet.” The idea was that as a result of a reduction in gastric volume and in the case of the gastric bypass operation, bypassing the proximal intestine, people were “forced” to eat less. What has increasingly become clear is that gastric bypass surgery is a complex neurohumoral treatment that alters appetite in a fundamental way by changing the signals that communicate information about food intake from the gastrointestinal (GI) tract to the brain and peripheral tissues. Taste and smell along with appearance not only identify a stimulus as being food but impart the food with rewarding or aversive qualities which in turn promote or inhibit intake. Over the last 10 years there have been tremendous advances in our understanding of taste stimuli with the identification of a number of taste receptors that are the molecular mediators of taste sensation. While the mouth plays an important role in taste, it is clear that taste receptors are distributed widely in the GI tract from the small intestine to the colon. New research also has shown that nutritional state plays an important role in setting the “gain” on the rewarding properties of food tastes. This study provides new evidence that gastric bypass surgery affects weight in part by changing the taste and smell perceptions of those who have had the surgery. These results reinforce the idea that the mechanisms by which weight loss surgery works are numerous and complex. Future research will look to understand the molecular mechanisms that underlie these changes in taste and smell.