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OBJECTIVE The aim of this study was to investigate the effect of bariatric surgery on sweet taste sensitivity and the hedonic evaluation of sweet, savory, and fatty food stimuli as well as associations with weight loss and food preferences assessed at a buffet meal test. METHODS The detection and recognition threshold for sweet taste and the hedonic rating of sweet, savory, and fatty food stimuli were assessed before and after a preoperative diet-induced weight loss and 6 weeks, 6 months, and 18 months after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) (n = 29). RESULTS The detection threshold for sweet taste decreased after the diet-induced weight loss and 6 weeks after RYGB (both P ≤ 0.03). The hedonic rating of high-fat food stimuli decreased 6 weeks after RYGB and SG (all P ≤ 0.02). Changes in the hedonic rating of high-fat food stimuli were associated with increased preferences for high-fat foods at the buffet meal (P = 0.03) and tended to be associated with weight loss (P = 0.05). No changes were detected for sweet and savory food stimuli. CONCLUSIONS RYGB increased sweet taste sensitivity; however, this effect was already seen after the diet-induced weight-loss. RYGB and SG decreased the hedonic evaluation of high-fat food stimuli, but this effect did not translate into decreased preferences for high-fat food.

Purpose: Bariatric surgery may shift food preferences towards less energy-dense foods. Eating behavior is multifactorial, and the mechanisms driving changes in food preferences could be a combination of a physiological response to surgery and social and psychological factors. This exploratory study aimed to identify potential factors explaining the variation in changes in food preferences after bariatric surgery. Materials and methods: Physiological, social, and psychological data were collected before, 6 weeks or 6 months after surgery. All variables were analyzed in combination using LASSO regression to explain the variation in changes in energy density at an ad libitum buffet meal 6 months after bariatric surgery (n=39). Results: The following factors explained 69% of the variation in changes in food preferences after surgery and were associated with more favorable changes in food preferences (i.e., a larger decrease in energy density): female gender, increased secretion of glicentin, a larger decrease in the hedonic rating of sweet and fat and a fatty cocoa drink, a lower number of recent life crises, a low degree of social eating pressure, fulfilling the diagnostic criteria for binge eating disorder, less effort needed to obtain preoperative weight loss, a smaller household composition, a lower degree of self-efficacy and a higher degree of depression, nutritional regime competence, and psychosocial risk level. Conclusion: Factors explaining the variation in altered food preferences after bariatric surgery not only include a physiological response to surgery but also social and psychological factors. Graphical Abstract: [Figure not available: see fulltext.]

Bariatric surgery may shift food preferences towards less energy-dense foods. Eating behavior is multifactorial, and the mechanisms driving changes in food preferences could be a combination of a physiological response to surgery and social and psychological factors. This exploratory study aimed to identify potential factors explaining the variation in changes in food preferences after bariatric surgery.Physiological, social, and psychological data were collected before, 6 weeks or 6 months after surgery. All variables were analyzed in combination using LASSO regression to explain the variation in changes in energy density at an ad libitum buffet meal 6 months after bariatric surgery (n=39).The following factors explained 69% of the variation in changes in food preferences after surgery and were associated with more favorable changes in food preferences (i.e., a larger decrease in energy density): female gender, increased secretion of glicentin, a larger decrease in the hedonic rating of sweet and fat and a fatty cocoa drink, a lower number of recent life crises, a low degree of social eating pressure, fulfilling the diagnostic criteria for binge eating disorder, less effort needed to obtain preoperative weight loss, a smaller household composition, a lower degree of self-efficacy and a higher degree of depression, nutritional regime competence, and psychosocial risk level.Factors explaining the variation in altered food preferences after bariatric surgery not only include a physiological response to surgery but also social and psychological factors.

OBJECTIVE Using an ad libitum buffet meal targeting direct behavior, the authors of the current study previously reported no effect of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) surgery on food preferences 6 months after surgery. The current study investigated changes in food preferences at 18 months after surgery and whether changes in food preferences at 6 months predicted weight loss. METHODS Twenty food items separated into the following food categories were served at the buffet meal: high-fat, low-fat, sweet, savory, high-fat savory, high-fat sweet, low-fat savory, and low-fat sweet. Energy intake and intake from each of the food items were registered. Energy intake prior to the meal was standardized. RESULTS Thirty-nine subjects completed visits before surgery and 18 months following RYGB (n = 29) and SG (n = 10) surgery. Energy intake decreased 41% (4,470 ± 209 kJ vs. 2,618 ± 209 kJ, P

Background: Bariatric surgery leads to a substantial weight loss (WL), however, a subset of patients undergoing surgery fails to achieve adequate WL. The reason for the individual variation in WL remains unexplained. Using an exploratory cross-disciplinary approach, we aimed to identify preoperative and early postoperative factors explaining the variation in WL after bariatric surgery. Methods: Sixty-one subjects were recruited. Eighteen subjects did not receive surgery and three subjects dropped out, leaving a total sample of 40 subjects. Physiological, social, and psychological data were collected before and 6 months after surgery. All variables were analyzed in combination using a least absolute shrinkage and selection operator (LASSO) regression to explain the variation in WL 18 months after Roux-en-Y gastric bypass (n = 30) and sleeve gastrectomy (n = 10). Results: Mean WL was 31% (range: 10–52%). The following preoperative factors predicted 59% of the variation in WL: type of surgery (14%), diabetes status (12%), economic resources (9%), sex (7%), binge eating disorder (7%), degree of depression (5%), household type (3%), and physical activity (1%). Including information on early responses after surgery increased the ability to predict WL to 78% and was explained by early WL (47%), changes in energy density of food consumed from a buffet meal (9%), changes in glicentin (5%), degree of depression (5%), sex (5%), type of surgery (2%), economic resources (2%), and changes in drive for thinness (1%). Conclusions: Using a cross-disciplinary approach, a substantial part of the individual variation in WL was explained by a combination of basic patient characteristics, psychological profile, and social conditions as well as physiological, psychological and behavioral responses to surgery. These results suggest that patient characteristics collected in a cross-disciplinary approach may help determine predictors for less successful WL after bariatric surgery. If verified in larger cohorts this may form the basis for individualized postoperative support to optimize WL outcome.

BACKGROUND: Hypoglycemia is an increasingly recognized complication of bariatric surgery. Mechanisms contributing to glucose lowering remain incompletely understood. We aimed to identify differentially abundant plasma proteins in patients with post-bariatric hypoglycemia (PBH) after roux-en-Y gastric bypass (RYGB), compared to asymptomatic post-RYGB. METHODS: Proteomic analysis of blood samples collected after overnight fast and mixed meal challenge in individuals with PBH, asymptomatic RYGB, severe obesity, or overweight recruited from outpatient hypoglycemia or bariatric clinics. RESULTS: The top-ranking differentially abundant protein at 120 minutes after mixed meal was fibroblast growth factor 19 (FGF-19), an intestinally-derived hormone regulated by bile acid/FXR signaling; levels were 2.4-fold higher in PBH vs. asymptomatic post-RYGB (mean ± SEM: 1094±141 vs. 428±45, P

Bariatric surgery leads to a substantial decrease in energy intake. It is unclear whether this decrease in energy intake is simply due to eating smaller portions of the same food items or a shift in food preference towards less energy-dense foods. This review evaluates the existing literature on changes in food preferences after bariatric surgery and the potential mechanisms involved. Changes in food preferences have been reported; however, the evidence is mainly based on indirect measurements, such as self-reporting. When changes in food preferences are directly assessed, results contradict previous findings, indicating that results based on self-reporting must be interpreted with caution as they do not necessarily reflect actual behaviour. However, it seems that there could be inter-individual differences in the response to surgery. Future studies investigating changes in food preferences should not only focus on direct measured of behaviour but should also consider the heterogeneity of the response after bariatric surgery.

Lay summary: Human and animal studies have shown that chronic stress interfers with both homeostatic and hedonic appetite control. Here, we investigated the effect of chronic stress on food preferences and eating behavior in real life settings. In random order, fifty healthy students participated in two test periods of 4–5 days; a stressful period (one week prior to an examination) and a nonstressful period (four weeks after an examination). Food preferences were assessed by counting money spent on highly rewarding foods bought with gift certificates, and changes in eating behavior was further assessed by the Three Factor Eating Questionnaire. Cohen’s Perceived Stress Scale, the Recovery-Stress Questionnaire, heart rate variability and Cortisol awakening response were used to evaluate the level of stress. Data on glycemic control, blood pressure, physical activity and sleep were also collected. Forty-four subjects had complete data on the primary outcome. Self-perceived stress was higher and recovery lower in the exam period (p ≤.001). Subjects were less cognitively restrained (p =.037), less moderately-to-vigorously and lightly physically active (p ≤.037) and were more sedentary (p =.009) in the examination period. However, no difference was found in money spent on high reward foods, disinhibition or hunger between the examination and control condition. Furthermore, no differences in the physiological markers of stress, glycemic measures and sleep were found. Data does not convincingly support the hypothesis that perceived stress increases the preference for highly palatable foods or leads to adverse effects on different markers of health. However, the stressor might have been to mild to induce obesogenic behaviors.

Using an ad libitum buffet meal targeting direct behavior, the authors of the current study previously reported no effect of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) surgery on food preferences 6 months after surgery. The current study investigated changes in food preferences at 18 months after surgery and whether changes in food preferences at 6 months predicted weight loss.Twenty food items separated into the following food categories were served at the buffet meal: high-fat, low-fat, sweet, savory, high-fat savory, high-fat sweet, low-fat savory, and low-fat sweet. Energy intake and intake from each of the food items were registered. Energy intake prior to the meal was standardized.Thirty-nine subjects completed visits before surgery and 18 months following RYGB (n = 29) and SG (n = 10) surgery. Energy intake decreased 41% (4,470 ± 209 kJ vs. 2,618 ± 209 kJ, P 0.001), but no change occurred in relative energy intake from any of the food categories (all P ≥ 0.23), energy density (P = 0.20), or macronutrient intake (all P ≥ 0.28). However, changes in high-fat food intake, protein intake, energy intake, and energy density at 6 months predicted weight loss at 18 months (P ≤ 0.02).RYGB surgery and SG surgery do not affect food preferences. However, changes in food preferences seem to be predictive of weight loss.

Increased energy expenditure (EE) has been proposed as an important mechanism for weight loss following Roux-en-Y gastric bypass (RYGB). However, this has never been investigated in a controlled setting independent of changes in energy balance. Similarly, only few studies have investigated the effect of RYGB on glycaemic control per se. Here, we investigated the effect of RYGB on EE, appetite, glycaemic control and specific signalling molecules compared with a control group in comparable negative energy balance. Obese normal glucose-tolerant participants were randomized to receive RYGB after 8 (n=14) or 12 weeks (n=14). The protocol included a visit at week 0 and three visits (weeks 7, 11 and 78) where 24-h EE, appetite and blood parameters were assessed. Participants followed a low-calorie diet from weeks 0–11, with those operated at week 12 serving as a control group for those operated at week 8. Compared with controls, RYGB-operated participants had lower body composition-adjusted 24-h EE and basal EE 3 weeks postoperatively (both P

Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) lead to a reduction in energy intake. It is uncertain whether this reduction is simply due to eating smaller portions or if surgery changes food preferences towards less energy-dense food. Previous results rely on verbal reports, which may be prone to recall bias and underestimation of especially unhealthy foods. Using an ad libitum buffet meal targeting direct behavior, we investigated if RYGB and SG surgery leads to changes in food preferences. In addition, we assessed food preferences by a picture display test to explore differences between a method relying on verbal report and a method assessing direct behavior. Forty-one subjects (BMI 45.0 ± 6.8 kg/m2) completed a visit pre- and 6 months post-RYGB (n = 31) and SG (n = 10). Mean BMI decreased with 11.7 ± 0.6 kg/m2 and total energy intake at the buffet meal with 54% (4491 ± 208 kJ vs. 2083 ± 208 kJ, P

Our aim was to examine the effects of GLP-1 and PYY3–36, separately and in combination, on energy intake, energy expenditure, appetite sensations, glucose and fat metabolism, ghrelin, and vital signs in healthy overweight men. Twenty-five healthy male subjects participated in this randomized, double-blinded, placebo-controlled, four-arm crossover study (BMI 29 ± 3 kg/m2, age 33 ± 9 yr). On separate days they received a 150-min intravenous infusion of 1) 0.8 pmol·kg−1·min−1 PYY3–36, 2) 1.0 pmol·kg−1·min−1 GLP-1, 3) GLP-1 + PYY3–36, or 4) placebo. Ad libitum energy intake was assessed during the final 30 min. Measurements of appetite sensations, energy expenditure and fat oxidation, vital signs, and blood variables were collected throughout the infusion period. No effect on energy intake was found after monoinfusions of PYY3–36 (−4.2 ± 4.8%, P = 0.8) or GLP-1 (−3.0 ± 4.5%, P = 0.9). However, the coinfusion reduced energy intake compared with placebo (−30.4 ± 6.5%, P < 0.0001) and more than the sum of the monoinfusions ( P < 0.001), demonstrating a synergistic effect. Coinfusion slightly increased sensation of nausea ( P < 0.05), but this effect could not explain the effect on energy intake. A decrease in plasma ghrelin was found after all treatments compared with placebo (all P < 0.05); however, infusions of GLP-1 + PYY3–36 resulted in an additional decrease compared with the monoinfusions (both P < 0.01). We conclude that coinfusion of GLP-1 and PYY3–36 exerted a synergistic effect on energy intake. The satiating effect of the meal was enhanced by GLP-1 and PYY3–36 in combination compared with placebo. Coinfusion was accompanied by slightly increased nausea and a decrease in plasma ghrelin, but neither of these factors could explain the reduction in energy intake.

It has been suggested that a shift in food choices leading to a diet with a lower energy density plays an important role in successful weight loss after Roux-en-Y gastric bypass (RYGB) surgery. A decreased hedonic drive to consume highly palatable foods may explain these changes in eating behavior. Here, we review the literature examining postoperative changes in mechanisms contributing to hedonic drive (food preferences, reinforcing value of food, dopamine signaling, and activity reward-related brain regions). The majority of studies reviewed support that RYGB decrease the hedonic drive to consume highly palatable foods. Still, in order to fully understand the complexity of these changes, we need studies combining sociological and psychological approaches with objective measures of actual food choices examining different measures of hedonic drive.

A preoperative weight loss of 8 % is a prerequisite to undergo bariatric surgery (BS) in Denmark. The aim of the present study was to evaluate the efficacy of a 7- or an 11-week low-energy diet (LCD) for achieving preoperative target weight before BS. A total of thirty obese patients (BMI 46·0 (sd 4·4) kg/m2) followed an LCD (Cambridge Weight Plan®, 4184 kJ/d (1000 kcal/d)) for 7 or 11 weeks as preparation for BS. Anthropometric measurements including body composition (dual-energy X-ray absorptiometry), blood parameters and blood pressure were assessed at weeks 0, 7 and 11. At week 7, the majority of patients (77 %) had reached their target weight, and this was achieved after 5·4 (sem 0·3) weeks. Mean weight loss was 9·3 (sem 0·5) % (P sem 2·3) and 7·3 (sem 1·8) mmHg, respectively, all P sem 1·8) % decrease in fasting glucose (P sem 6·4) % decrease in fasting insulin (P sem 2·2) % decrease in LDL (P sem 4·7) % decrease in TAG (P P

To examine the effect on serum lipase activity and protein concentration of intravenous infusions of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY3-36) and of an ad libitum meal in healthy overweight men. Twenty-five healthy, male subjects participated in this randomized, double-blinded, placebo-controlled 4-arm crossover study (Body Mass Index (BMI): 29 ± 3 kg/m(2), age: 33 ± 9 years). On separate days, the subjects received a 150-min intravenous infusion of either (1) 0.8 pmol/kg/min PYY3-36, (2) 1.0 pmol/kg/min GLP-1, (3) 1 + 2, or (4) placebo. Samples were collected throughout the infusion and after intake of an ad libitum meal for measurement of serum lipase. Serum lipase levels measured by enzyme-linked immunosorbent assay (ELISA) following mono-infusions of GLP-1 and PYY3-36 were comparable to serum lipase levels following placebo (P = 0.054 and P = 0.873, respectively). Following the co-infusion of GLP-1 and PYY3-36, serum lipase levels measured by ELISA decreased over time compared to placebo (P = 0.012). However, the between-group difference was not consistent when each time point was analyzed separately. On the placebo day, serum lipase levels measured by ELISA after an ad libitum meal rose slightly compared to the preprandial values (P = 0.003). There was strong correlation between serum lipase levels measured by ELISA and LIPC Lipase colorimetric assay (COBAS) (0.94 < r

We briefly reviewed one definition of dose addition, which is applicable within the framework of generalized linear models. We established how this definition of dose addition corresponds to effect addition in case only two doses per compound are considered for evaluating synergistic effects. The link between definitions was exemplified for an appetite study where two appetite hormones were studied.