PICTURE: Sensitivity to sweetness predicts weight loss in bariatric surgery
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Photo credit: Diogo Matias

A study conducted by scientists at the Champalimaud Center for Unknowns in Lisbon concludes that bariatric surgery – that is, the method of treating severe obesity by reconfiguring the gastrointestinal tract – in patients who had an increased perception of before surgery Sweet.

Although bariatric surgery is the most effective treatment for severe obesity, the outcome of the procedure in terms of weight loss varies significantly from patient to patient. Understanding why some patients benefit from bariatric surgery more than others can therefore be of paramount importance in assessing what to expect from the surgery for a particular patient – and ultimately, in deciding whether it will be performed on that patient at all shall be.

A combination of factors can play a role in inducing postoperative weight loss. It is certain that surgery leads to a reduction in food consumption, but the biological mechanisms underlying this behavior change remain unclear. For example, surgery could result in changes in the purely sensory reward experience that results from tasting high calorie and sweet foods. On the other hand, it could also be the result of changes at the psychological level where the reward that comes from eating this type of food is linked to the activation of reward centers in the brain itself. This susceptibility to environmental food stimuli has been termed “hedonic hunger”.

According to our hypothesis, the authors write in their article just published in the American Journal of Clinical Nutrition “the primary independent variables” [that were tested] were the mean intensity and comfort ratings [of sweetness] as well as the scores for hedonic hunger and addiction-like feeding behavior. “The new study asked if it was possible to predict the extent of post-surgery weight loss by performing both sensory and psychological assessments prior to surgery. Measurements of food reward.” The main aim of the study was to understand whether these preoperative measurements predicted the weight loss that was lost approximately a year after surgery, “says senior co-author Albino Oliveira-Maia, head of the neuropsychiatry department at the Champalimaud Center for that Unknown.

“A large group of obese patients who were recruited in several Portuguese hospitals (namely Espírito Santo Hospital in Évora, São Bernardo Hospital in Setúbal and São João University Hospital in Porto) had previously been rewarded with measures Food collected Oliveira-Maia adds: “These measures were both psychological and sensory, and the measurements were also repeated after the operation.”

“Measurements of food reward were made using both questionnaires and sensory assessments of taste, including the intensity and comfort of sucrose in patients who were followed up for more than a year after surgery,” said Gabriela Ribeiro, lead author of the Study further specifies. “As a control, we also examined patients who were still on the waiting list for operations and therefore received non-surgical treatment.”

The data were collected from November 2012 to June 2017. In the control group, 50 patients underwent a single control visit two to 18 months after the first visit, while in the surgical group 96 patients were examined early (3 to 6 months) and / or late (11 to 18 months) follow-up after surgery.

Several surprises

The scientists found that both sweet intensity and hedonic hunger (susceptibility to food stimuli) predicted the amount of weight lost approximately a year after surgery. “Since our main hypothesis was that the variability in reward-related feeding behavior would predict weight loss after surgery, our results confirmed our hypothesis,” says Ribeiro.

However, three surprises lurked in these novel results. First, the associations between any type of measurement and the amount of weight loss went in opposite directions. In other words, in patients with higher hedonic hunger, the operation was less effective; and for patients with higher sensory sensitivity to food reward, the surgery was more effective. “It was surprising to find that two different measures of food reward – in this case, hedonic hunger and the taste perception of sweetness – would predict the outcomes of bariatric surgery in opposite ways,” Ribeiro points out.

Second, although both hedonic hunger and sweet taste perception predicted weight loss, only changes in sweet taste intensity perception were related to the extent of weight loss, not to sweet taste comfort (which the scientists, as previously mentioned, have also measured). “This is also new and surprising,” says Ribeiro. While changes in hedonic hunger after surgery were not associated with weight loss, the patients who experienced the greatest weight loss after surgery were also those who were noted to have greater reductions in perception of sweet intensity.

According to the study’s authors, finding that increased perception of sweet intensity is a predictor of greater weight loss after bariatric surgery, along with the discovery that a decrease in this sensory area was also associated with greater weight loss, “is a” one References to the perception of sweet intensity may reflect biological mechanisms by which bariatric surgery is effective “.

“A better understanding of these mechanisms could have implications for improving bariatric outcomes – for example through personalized patient selection – as well as developing novel therapies for obese patients that target these mechanisms.” concludes Ribeiro.


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