Reported appetite, taste and smell changes following Roux-en-Y gastric bypass and sleeve gastrectomy: Effect of gender, type 2 diabetes and relationship to post-operative weight loss

Stronger control of eating 3 months after sleeve gastrectomy predicts successful weight loss outcomes at one year

Background

Weight loss response to sleeve gastrectomy (SG) is variable and predicting the effectiveness of surgery is challenging and elusive. The aim of our study was to assess and quantify the association between eating control and weight loss outcomes and identify the control of eating (CoE) attributes during the early postoperative period that might predict good vs. poor response to SG at one year.

Methods

A prospective longitudinal cohort study using the Control of Eating Questionnaire (CoEQ) was designed as a series before and at 3-, 6-, and 12-months post-SG. Primary outcomes were changes in CoE attributes and percent of total weight loss (%TWL) 12-months post-surgery. Subjects were categorized based on %TWL as good (GR, ≥25 %) or poor responders (PR, <25 %). A receiver operating characteristic and logistic regression analyses were performed.

Results

We included 41 participants (80.5% females, 51.2% Hispanic, mean age 41.7±10.6, median baseline body mass index (BMI) 43.6 kg/m2 [range 35.2-66.3]) who completed the CoEQ at all four timepoints. The "Difficulty to control eating" score at 3 months revealed the highest area under the curve (AUC) (AUC 0.711; 95%CI 0.524-0.898; p=0.032). In a trade-off between a high Youden index and high sensitivity, the "Difficulty to control eating" score of 7 at 3 months was identified as the optimal cut-off for distinguishing between GRs and PRs. Score ≤7 at 3 months was strongly independently associated with a successful weight loss target of 25%TWL at one-year post-SG (Relative Risk 4.43; 95%CI 1.06-18.54; p=0.042).

Conclusion

"Difficulty to control eating" score at 3 months post-SG is an independent early predictor of optimal response (achieving a successful TWL target of ≥25 % at one-year post-SG). Our results support the utility of this easy-to-administer validated tool for predicting the effectiveness of SG and may assist in identifying individuals with suboptimal response early and helping them with interventions to attain optimal weight loss targets.

Changes in Food Preferences Before and After Intragastric Balloon Placement

BACKGROUNDS

In recent years, numerous studies have tried to decode the way bariatric surgery works toward weight reduction by the use of food preference questionnaires. The intragastric balloon has gained popularity, mainly due to its limited invasiveness, in patients with obesity not fulfilling criteria for bariatric surgery. However, there is no study assessing the changes in food preferences [FP]. We decided to analyze the FP of individuals prior to intragastric balloon insertion and following its removal, on the strict condition that participants must complete the 6-month treatment period and attend at least 4 of the 7 follow-up interviews.

METHODS

Patients were asked to rate the frequency of consumption of 63 food items before balloon insertion, at monthly intervals and after balloon removal. The food categories were protein, carbohydrates, fruit and vegetables, and sweets and fats.

RESULTS

The questionnaires of 320 participants were analyzed. A reduced frequency in consumption of meat and meat products, high-fat, and high-carbohydrate/sugary products and an increase in raw vegetables and fruit was found in all individuals.

CONCLUSION

The intragastric balloon seems to exert analogically similar mechanisms to bariatric surgery for weight loss, both functioning through alterations in FP. These are dictated by the anatomical re-configuration of the stomach, but mainly by counseling of dieticians and the self-education of the patient after experiencing unpleasant postprandial discomfort.

Control of Eating Attributes and Weight Loss Outcomes over One Year After Sleeve Gastrectomy

PURPOSE

Sleeve gastrectomy (SG) is a commonly performed metabolic-bariatric surgery, but its effectiveness is variable and difficult to predict. Our study aimed to compare control of eating (CoE) attributes pre- and post-SG depending on the achievement of optimal weight loss target at 1 year post-SG.

MATERIALS AND METHODS

A prospective longitudinal cohort study using the CoE Questionnaire, pre-SG, and postoperatively at 3, 6, and 12 months was conducted. Total weight loss (TWL) ≥ 25% at 12 months post-SG was set as an optimal weight loss target.

RESULTS

Forty-one patients (80.5% females, mean age 41.7 ± 10.6) were included. Sex, age, baseline weight, BMI, and smoking status were all comparable. At 3 months post-SG, "difficulty to control eating" score became significantly different between ≥ 25%TWL and < 25%TWL groups (7 [0-50] vs. 17 [5-63], p = 0.042). At 6 months, it was followed by "feeling of fullness," "frequency of food cravings," and "difficulty to resist cravings" demonstrating significant differences between ≥ 25%TWL and < 25%TWL groups. At 12 months, significant differences between groups were observed in "feeling hungry," "difficulty to resist cravings," "eating in response to cravings," and difficulty to control eating scores.

CONCLUSION

Individuals with obesity who achieved a target of ≥ 25%TWL at 1 year post-SG have an early improvement in overall eating control at 3 months that steadily persists at 6 and 12 months. Improvements in other aspects tend to follow later, at 6 and 12 months. These findings may assist in identifying individuals with inadequate response to help attain optimal weight loss targets and developing a prognostic model to identify predictors of successful weight loss.

The Association Between Appetite and Quality of Life in Adults with Obesity or Severe Obesity Post-Sleeve Gastrectomy Procedure: A Cross-Sectional Study

Background

Sleeve gastrectomy (SG) is considered as the most common bariatric procedure in Saudi Arabia. It is a non-reversible procedure defined as removal of a large portion of the stomach.

Objective

The objective of the current study is to compare the appetite and quality of life (QoL) between adults' post-sleeve gastrectomy and obese/morbidly obese adults (pre-SG).

Methods

A cross-sectional study design was conducted in adults (aged between 18 and 65 years), post-sleeve gastrectomy (n = 80, 41 Males and 39 Females) and obese group (n = 60, 28 Males and 32 Females). The study population was recruited from the bariatric surgery clinic of King Abdullah Bin Abdul-Aziz University Hospital. A self-reported questionnaire was collected that included a visual analogue scale (VAS) to assess the appetite level, and SF-36 QoL questionnaire.

Results

No significant differences were found in age and gender between the study groups (p > 0.05). The median score feeling of fullness was significantly higher in the SG group (77.5, IQR: 48 and 50, IQR: 40, respectively) than in the obese group (p < 0.001). The amount of food eaten was statistically lower in the SG group (30, IQR: 20) than the obese group (50, IQR: 60) (p = 0.005). Patients post SG had significantly higher QoL scores in all physical and mental scales, physical component summary and mental component summary (p < 0.003).

Conclusion

Patients post SG have improved appetite and QoL. Satiety, less prospective food consumption, BMI, age, gender and comorbidities are associated with QoL. Future studies are needed to compare the QoL in post-SG patients with the normative values of the QoL in Saudi Arabia.

Food cravings after bariatric surgery: comparing laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass

BACKGROUND

Research suggests that food choices, preferences, and tastes change after bariatric surgery, but evidence regarding changes in food cravings is mixed.

OBJECTIVES

The primary aim of this cohort study was to compare food cravings during the first year following bariatric surgery in patients who had undergone sleeve gastrectomy (SG) versus Roux-en-Y gastric bypass (RYGB).

SETTING

Integrated multispecialty health system, United States.

METHODS

Patients aged ≥ 18 years seen between May 2017 and July 2019, provided informed consent, completed the Food Craving Inventory (FCI), and had ≥ 1 year of follow-up after undergoing primary SG or RYGB were included in the study. Secondary data captured included psychological and behavioral measures. Preoperative and postoperative (3, 6, 9, and 12 months) FCI scores of patients who underwent SG and RYGB were compared.

RESULTS

Some attrition occurred postoperatively (N = 187 at baseline, 141 at 3 months, 108 at 6 months, 89 at 9 months, and 84 at 12 months). No significant relationship between pre- or postoperative food cravings and surgery type was found except on the carbohydrate subscale. Patients with higher preoperative food addiction symptoms were not more likely to experience an earlier reoccurrence of food cravings during the first 12 months after surgery. Likewise, patients with higher levels of preoperative depression and anxiety were not more likely to have early reoccurrence of food cravings during the first 12 months after surgery; however, those with higher PHQ9 scores at baseline had uniformly higher food craving scores at all timepoints (pre-surgery, 3 m, 6 m, 9 m, and 12 m).

CONCLUSIONS

Results suggest that food cravings in the year after bariatric surgery are equivalent by surgery type and do not appear to be related to preoperative psychological factors or eating behaviors.

LEVEL OF EVIDENCE

Level III: Evidence obtained from well-designed cohort.

The Role of the Olfactory System in Obesity and Metabolism in Humans: A Systematic Review and Meta-Analysis

Obesity, linked to chronic diseases, poses a global health challenge. While the role of the olfactory system in energy homeostasis is well-documented in rodents, its role in metabolism regulation and obesity in humans remains understudied. This review examines the interplay between olfactory function and metabolic alterations in human obesity and the effects of bariatric surgery on olfactory capabilities in humans. Adhering to PRISMA guidelines, a systematic review and meta-analysis was conducted, focusing exclusively on original human studies. From 51 articles, 14 were selected for the meta-analysis. It was found that variations in olfactory receptor genes influence the susceptibility to odors and predisposition to weight gain and poor eating habits. Bariatric surgery, particularly sleeve gastrectomy, shows significant improvements in olfactory function (SMD 2.37, 95% CI [0.96, 3.77], I = 92%, p = 0.001), especially regarding the olfactory threshold (SMD -1.65, 95% CI [-3.03, -0.27], I = 81%, p = 0.02). There is a bidirectional relationship between olfactory function and metabolism in humans. Bariatric surgery improves olfactory perception in obese patients, but it is still unclear if impacting the olfactory system directly affects eating behavior and the energy balance. However, these findings open novel avenues for future studies addressing the olfactory system as a novel target to alter systemic metabolism in humans.

Smell, taste and food habits changes along body mass index increase: an observational study

PURPOSE

To evaluate the changes in gustatory and olfactory sensitivity and dietary habits between healthy lean subjects (LS) and participants affected by overweight (OW), stage I and II obesity and to estimate possible impact of these factors on body mass index (BMI).

METHODS

After a general and ear-nose-throat evaluation, taste and olfactory function testing by means of taste strips and sniffin' stick tests, respectively, and food habits analysis by means of food frequency questionnaire (FFQ), 221 participants (68 LS [33 female; mean age = 53.01 ± 7.54 years]; 51 OW [26 female; mean age = 51.5 ± 12.16 years]; 50 stage I obesity [24 female; mean age = 50.78 ± 13.71 years] and 52 stage II obesity [24 female; mean age = 52.21 ± 13.35 years]) were enrolled in the study.

RESULTS

Significant (p < 0.008) reductions in total and subtest taste and smell scores were found in stage I and II obesity when compared to LS and OW participants. FFQ depicted a progressive intake increase of nutrients along the BMI stages. Significant associations were found between BMI and taste/smell subtests sugar taste carbs, saturated, monounsaturated and polyunsaturated fatty acids.

CONCLUSIONS

These data demonstrated for the first time a parallel impairment in smell and taste in a large sample size of participants from lean to stage II obesity and could reinforce those previous theories claiming that the greater the ability in taste or smell qualities perception, the lower the preference for them, resulting in a lower intake of specific foods.

Development and complications of nutritional deficiencies after bariatric surgery

The clinical effectiveness of bariatric surgery has encouraged the use of bariatric procedures for the treatment of morbid obesity and its comorbidities, with sleeve gastrectomy and Roux-en-Y gastric bypass being the most common procedures. Notwithstanding its success, bariatric procedures are recognised to predispose the development of nutritional deficiencies. A framework is proposed that provides clarity regarding the immediate role of diet, the gastrointestinal tract and the medical state of the patient in the development of nutritional deficiencies after bariatric surgery, while highlighting different enabling resources that may contribute. Untreated, these nutritional deficiencies can progress in the short term into haematological, muscular and neurological complications and in the long term into skeletal complications. In this review, we explore the development of nutritional deficiencies after bariatric surgery through a newly developed conceptual framework. An in-depth understanding will enable the optimisation of the post-operative follow-up, including detecting clinical signs of complications, screening for laboratory abnormalities and treating nutritional deficiencies.

Taste Function in Adult Humans from Lean Condition to Stage II Obesity: Interactions with Biochemical Regulators, Dietary Habits, and Clinical Aspects

Differences in gustatory sensitivity, nutritional habits, circulating levels of modulators, anthropometric measures, and metabolic assays may be involved in overweight (OW) development. The present study aimed at evaluating the differences in these aspects between 39 OW (19 female; mean age = 53.51 ± 11.17), 18 stage I (11 female; mean age = 54.3 ± 13.1 years), and 20 II (10 female; mean age = 54.5 ± 11.9) obesity participants when compared with 60 lean subjects (LS; 29 female; mean age = 54.04 ± 10.27). Participants were evaluated based on taste function scores, nutritional habits, levels of modulators (leptin, insulin, ghrelin, and glucose), and bioelectrical impedance analysis measurements. Significant reductions in total and subtests taste scores were found between LS and stage I and II obesity participants. Significant reductions in total and all subtests taste scores were found between OW and stage II obesity participants. Together with the progressive increase in plasmatic leptin levels, insulin, and serum glucose, decrease in plasmatic ghrelin levels, and changes in anthropometric measures and nutritional habits along with body mass index, these data for the first time demonstrated that taste sensitivity, biochemical regulators, and food habits play a parallel, concurring role along the stages evolving to obesity.

Prevalence of food addiction among patients undergoing metabolic/bariatric surgery: A systematic review and meta-analysis

Candidates for metabolic/bariatric surgery show a high prevalence of food addiction (FA). However, few studies have investigated FA prevalence after bariatric surgery, especially using longitudinal studies. This systematic review with a meta-analysis aimed to determine pre- and postoperative prevalence of FA among patients undergoing metabolic/bariatric surgery. It included both cross-sectional and longitudinal studies that used the Yale Food Addiction Scale (YFAS). The following databases were searched: MEDLINE, ScienceDirect, LILACS, PsycArticles, CENTRAL, greylit.org, and opengrey.eu. Studies that used the YFAS to evaluate FA in pre- or postoperative patients were included. A random-effects meta-analysis was performed with cross-sectional studies to calculate the weighted prevalence of FA at the pre- and postoperative moments. For longitudinal studies, which measured FA at both time points for the same individuals, absolute prevalence reduction (APR) was calculated. Of the 6626 records, 40 studies were included in the meta-analysis. The preoperative weighted prevalence of FA was 32% (95% CI: 27-37%; 33 groups), whereas the postoperative prevalence was 15% (95% CI: 12-18%; 14 groups). Seven longitudinal studies showed a weighted APR of 26 p.p. (95% CI: 10-41 p.p.). Observational data suggest a reduction in the prevalence of FA among patients that undergo bariatric surgery. Interventional studies are needed to confirm these findings.

A Literature Review of Taste Change and Zinc Deficiency After Bariatric Surgery: Could There Be a Causal Link?

In this review, we collated evidence relating to taste change and zinc deficiency in relation to bariatric surgery (BS) and effects of zinc replacement on taste perception and speculate on the possible role of zinc deficiency to induce taste change after BS. A literature search was conducted (33 studies, N = 3264). We showed that taste change and zinc deficiency are frequent complications after BS, which both typically occurred at 6 months post-surgery. Our analysis did not support a causal link between the two, but similar onset of incidences indirectly indicates a link. Supplementation with 45-50 mg of zinc sulphate, higher than current recommendation, was effective in improving taste. Further studies are required to establish the causal link between the two in the context of BS.

The Neural Code for Taste in the Nucleus of the Solitary Tract of Rats with Obesity Following Roux-En-Y Gastric Bypass Surgery

Previous work has shown that taste responses in the nucleus tractus solitarius (NTS; the first central relay for gustation) are blunted in rats with diet-induced obesity (DIO). Here, we studied whether these effects could be reversed by Roux-en-Y gastric bypass (RYGB) surgery, an effective treatment for obesity. Rats were fed a high energy diet (60% kcal fat; HED) both before and after undergoing RYGB. Electrophysiological responses from NTS cells in unrestrained rats were recorded as they licked tastants from a lick spout. Sweet, salty, and umami tastes, as well as their naturalistic counterparts, were presented. Results were compared with those of lean rats from a previous study. As with DIO rats, NTS cells in RYGB rats were more narrowly tuned, showed weaker responses, and less lick coherence than those in lean rats. Both DIO and RYGB rats licked at a slower rate than lean rats and paused more often during a lick bout. However, unlike DIO rats, the proportion of taste cells in RYGB rats was similar to that in lean rats. Our data show that, despite being maintained on a HED after surgery, RYGB can induce a partial recovery of the deficits seen in the NTS of DIO rats.

Impact of sleeve gastrectomy compared to Roux-en-y gastric bypass upon hedonic hunger and the relationship to post-operative weight loss

'Hedonic hunger' indicates the desire to consume food in the absence of an energy requirement. Hedonic hunger can be investigated using the validated Power of Food Scale (PFS). Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are currently the most effective treatment options for severe obesity. Following RYGB, hedonic hunger diminishes, which may contribute to sustained weight loss. There are no data examining the effect of SG on hedonic hunger. We prospectively evaluated hedonic hunger using PFS in patients with severe obesity prior to and 6 months after SG (n = 95) or RYGB (n = 44) and investigated the procedure-specific relationship between percentage weight loss (%WL) and hedonic hunger. Anthropometric data were collected at baseline after 6 months, 12 months and 24 months post-operatively. PFS contains 15 items grouped into 3 domains considering when food is: available (FA), present (FP), tasted (FT) and a total score (TS). At 6 months, a significant reduction was seen in all categories post-SG (p < 0.0001) and in TS (p = 0.003), FA (p = 0.0006) and FP (p = 0.0007) post-RYGB. A significantly larger reduction in FP scores was seen post-SG (p = 0.01). Post-SG, a significant correlation with 6-month %WL was noted for changes in FP (p = 0.03) and TS (p = 0.03). Post-SG changes in FP and TS predicted 24-month %WL. Post-RYGB significant correlations were seen between 6-month %WL and dFA (p = 0.04) and dFP (p = 0.03). Changes in FA, FP and TS were predictive of 12-month %WL. HH is reduced following both SG and RYGB with a greater reduction following SG and is related to post-operative %WL. PFS may have a role as a predictive tool for post-operative outcomes following SG and RYGB.

One-Year Self-Reported Appetite Is Similar in Adolescents with Obesity Who Do or Do Not Undergo Sleeve Gastrectomy

BACKGROUND

With the growing prevalence of severe obesity in adolescents, sleeve gastrectomy (SG), a type of metabolic bariatric surgery (MBS), is increasingly being performed at a younger age. Data regarding changes in homeostatic and hedonic appetite following SG are conflicting in adults, with some studies showing no change and others showing a decrease in appetite. Data evaluating the effect of SG on appetite during adolescence, when appetite is more plastic, are currently lacking.

OBJECTIVE

To evaluate appetite changes one year after SG in adolescents with obesity vs. in non-surgical controls (NS).

METHODS

Thirty-nine subjects 13-21 years old with severe obesity were followed for a year; 19 underwent SG, and 20 were followed without surgery. Subjects had fasting blood tests for appetite-regulating hormones and completed a visual analog scale for appetite assessment (VAS).

RESULTS

The SG group had a decrease in body mass index (BMI) at one-year (baseline: 48.2 ± 1.7 kg/m2; one-year follow-up: 42.6 ± 1.0 kg/m2 (p ≤ 0.0001)). No within- or between-group differences were noted in the one-year change in appetite in the SG and NS groups. After SG, fasting ghrelin decreased (p ≤ 0.0001); however, no changes were noted in peptide YY (PYY) levels. Changes in one homeostatic appetite measure following SG were inversely associated with changes in fasting PYY (r = -0.583, p = 0.011). Appetite changes were not associated with weight loss or final BMI.

CONCLUSIONS

There were no changes in appetite measures one-year after SG from pre-surgery levels in adolescents with obesity, and appetite changes were not associated with changes in BMI. It is important to evaluate the impact of long-term appetite changes, if any, on weight loss after SG.

Changes in Food Choice, Taste, Desire, and Enjoyment 1 Year after Sleeve Gastrectomy: A Prospective Study

Obesity is a well-recognized global health problem, and bariatric surgery (BS)-induced weight reduction has been demonstrated to improve survival and obesity-related conditions. Sleeve gastrectomy (SG) is actually one of the most performed bariatric procedures. The underlying mechanisms of weight loss and its maintenance after SG are not yet fully understood. However, changes to the taste function could be a contributing factor. Data on the extent of the phenomenon are limited. The primary objective was to assess, through validated questionnaires, the percentage of patients who report an altered perception of post-SG taste and compare the frequency of intake of the different food classes before SG and after 1 year follow-up. The secondary objective was to evaluate the total body weight change. Materials and Methods: We prospectively investigated the changes in food choice and gustatory sensitivity of 52 patients (55.8% females) 12 months after SG. The mean initial weight and body mass index (BMI) were 130.9 ± 24.7 kg and 47.4 ± 7.1 kg/m2, respectively. The frequency of food intake was assessed by food-frequency questionnaire, while changes in taste perception were assessed using the taste desire and enjoyment change questionnaire. The change in total body weight was also assessed. Results: A significant decrease in the intake frequency of bread and crackers (p < 0.001), dairy products and fats (p < 0.001), sweets and snacks (p < 0.001) and soft drinks (p < 0.001), and a significant increase in the frequency of vegetable and fruit consumption (p < 0.001) were observed at 12 months after SG in both genders. On the contrary, we found no significant changes in the frequency of meat and fish intake in females (p = 0.204), whereas a significant change was found in males (p = 0.028). Changes in perceived taste intensity of fatty foods (p = 0.021) and tart foods (p = 0.006) for females and taste of bitter foods for females and males (p = 0.002; p = 0.017) were found. Regarding the change in food desire for both genders, there was a decrease in the desire for sweet, fatty, and salty foods, whereas there was an increasing trend in the desire for tart foods, especially for females. Significant reduction in total body weight and BMI was observed in both genders at the time of follow-up. Conclusions: Based on our findings, we are able to support the evidence that changes in taste, desire, and enjoyment of taste are very common after SG, with a reduced preference for food with high sugar and fat content and an increased postoperative preference for low-sugar and -fat foods. However, further investigation is needed to clarify this issue. The molecular, hormonal, and central mechanisms underlying these changes in taste perception need to be further elucidated, as they could identify new targets able to modify obesogenic eating behavior, opening up a novel personalized therapeutic approach to obesity.

Early Postoperative Exposure to High-Fat Diet Does Not Increase Long-Term Weight Loss or Fat Avoidance After Roux-en-Y Gastric Bypass in Rats

Background

Bariatric surgery alters food preferences in rats and reportedly decreases desire to consume high-fat high-sugar food in humans. The aim of this study was to investigate whether early post-operative exposure to high-fat food could increase body weight loss after Roux-en-Y gastric bypass (RYGB) by triggering fat avoidance.

Methods

Male Wistar rats underwent either RYGB (n = 15) or sham-operations (n = 16). Preoperatively a standardized 4-choice cafeteria diet [dietary options: low-fat/low-sugar (LFLS), low-fat/high-sugar (LFHS), high-fat/low-sugar (HFLS), high-fat/high-sugar (HFHS)] was offered. First, each option was available for 4 days, thereafter rats were offered the 4 options simultaneously for 3 days preoperatively. Post-surgery, 8 rats in the RYGB- and 8 in the sham-group were exposed to a high-fat content diet (Oatmeal + 30% lard, OM+L) for 10 days, while 7 RYGB rats and 8 sham-rats received OM alone. From the 11th postoperative day, the 4-choice cafeteria diet was reintroduced for 55-days. The intake of all available food items, macronutrients and body weight changes were monitored over 8 weeks. Main outcomes were long-term body-weight and daily change in relative caloric intake during the postoperative cafeteria period compared to the preoperative cafeteria.

Results

During the first 12 days of postoperative cafeteria access, RYGB-rats exposed to OM+L had a higher mean caloric intake per day than RYGB rats exposed to OM alone (Δ10 kCal, P_adj = 0.004), but this difference between the RYGB groups disappeared thereafter. Consequently, in the last 33 days of the postoperative cafeteria diet, the mean body weight of the RYGB+OM+L group was higher compared to RYGB+OM (Δ51 g, P_adj < 0.001). RYGB rats, independently from the nutritional intervention, presented a progressive decrease in daily consumption of calories from fat and increased their daily energy intake mainly from non-sugar carbohydrates. No such differences were detected in sham-operated controls exposed to low- or high fat postoperative interventions.

Conclusion

A progressive decrease in daily fat intake over time was observed after RYGB, independently from the nutritional intervention. This finding confirms that macronutrient preferences undergo progressive changes over time after RYGB and supports the role of ingestive adaptation and learning. Early postoperative exposure to high-fat food failed to accentuate fat avoidance and did not lead to superior weight loss in the long-term.

Associations of physical activity and sedentary behavior with appetite sensations and eating regulation behaviors before and during the initial year following bariatric surgery

Background

Bariatric surgery produces weight loss in part by impacting appetite and eating behavior. Research suggests physical activity (PA) assists with regulation of appetite and eating during non-surgical weight loss, although whether PA carries similar benefits in the context of bariatric surgery is unknown.

Objective

Evaluate associations of moderate-to-vigorous intensity PA (MVPA) and sedentary time (ST) with appetite sensations (hunger [homeostatic/hedonic], satiety) and eating regulation behaviors (restraint, disinhibition) before and during the initial year following bariatric surgery.

Method

Adult bariatric patients received an accelerometer to measure MVPA/ST and a smartphone to complete appetite/eating ratings at four semi-random times daily for 10 days at pre- and 3-, 6-, and 12-months post-surgery. Data were analyzed using generalized linear mixed models.

Results

Higher MVPA levels related to more satiety across time (p = 0.045) and more restraint at 3-months post-surgery (p < 0.001). At pre-surgery, higher MVPA levels also related to more disinhibition (p's < 0.01), although participants reported more disinhibition on days they performed less MVPA than usual (p = 0.017). MVPA did not relate to hunger. Lower ST levels related to more hedonic hunger (p = 0.003), especially at 12-months post-surgery (p < 0.001), and participants reported more homeostatic hunger on days they accumulated more ST than usual (p = 0.044). Additionally, higher ST levels related to more disinhibition at 3-months post-surgery (p's < 0.01) and lower restraint at pre-surgery (p's < 0.05). ST did not relate to satiety.

Conclusions

This study is the first to show that MVPA and ST each associate with appetite and eating regulation in daily life before and during post-surgical weight loss. Results, while preliminary and requiring experimental confirmation, highlight potential for targeting bariatric patients' activity behaviors to enhance modulation of appetite, control of food intake, and resistance to overeating.

The Influence of Roux-en-Y Gastric Bypass and Diet on NaCl and Sucrose Taste Detection Thresholds and Number of Circumvallate and Fungiform Taste Buds in Female Rats

Roux-en-Y gastric bypass (RYGB) in rats attenuates preference for, and intake of, sugar solutions. Additionally, maintenance on a high-fat diet (HFD) reportedly alters behavioral responsiveness to sucrose in rodents in short-term drinking tests. Due to the fact that the behavioral tests to date rely on the hedonic value of the stimulus to drive responsiveness, we sought to determine whether taste detection thresholds to sucrose and NaCl are affected by these manipulations as measured in an operant two-response signal detection paradigm. Female rats were maintained on HFD or chow for 10 weeks, at which point animals received either RYGB or SHAM surgery followed by a gel-based diet and then powdered chow. Upon recovery, half of the rats that were previously on HFD were switched permanently to chow, and the other rats were maintained on their presurgical diets (n = 5–9/diet condition x surgery group for behavioral testing). The rats were then trained and tested in a gustometer. There was a significant interaction between diet condition and surgery on NaCl threshold that was attributable to a lower value in RYGB vs. SHAM rats in the HFD condition, but this failed to survive a Bonferroni correction. Importantly, there were no effects of diet condition or surgery on sucrose thresholds. Additionally, although recent evidence suggests that maintenance on HFD alters taste bud number in the circumvallate papillae (CV) of mice, in a subset of rats, we did not find that diet significantly influenced taste pores in the anterior tongue or CV of female rats. These results suggest that any changes in sucrose responsiveness in intake/preference or hedonically oriented tests in rats as a function of HFD maintenance or RYGB are not attributable to alterations in taste sensitivity.

The Effects of Roux-en-Y Gastric Bypass on Glucose- vs. Fructose-Associated Conditioned Flavor Preference

In rodents, repeated single-bottle exposures to distinctly flavored isocaloric glucose and fructose solutions, two sugars with different metabolic pathways, eventually lead to a preference for the former. Because Roux-en-Y gastric bypass (RYGB) surgery decreases preference for and intake of sugar solutions in rats, we tested whether RYGB would curtail the conditioning of a preference for a glucose-paired vs. fructose-paired flavor. RYGB (♂ n=11; ♀ n=10) and sham-operated (SHAM; ♂ n=9; ♀ n=10) rats were trained with a single bottle (30 min/day) containing 8% glucose solution flavored with either 0.05% grape or cherry Kool-Aid (Glu/CS^G) or 8% fructose solution with the alternative Kool-Aid flavor (Fru/CS^F) in an alternating fashion for 8 days. To determine baseline preferences, a 4-day 30-min two-bottle test was used to assess preference for Glu/CS^G vs. Fru/CS^F before training. After training, 2-day 30-min two-bottle tests assessed preference for the a) Glu/CS^G (CS^G-flavored 8% glucose solution) vs Fru/CS^F (CS^F-flavored 8% fructose solution), b) CS^G- vs. CS^F-flavored mixture of 4% glucose & 4% fructose (isocaloric), c) CS^G- vs. CS^F-flavored 0.2% saccharin ("sweet", no calories), and d) CS^G- vs. CS^F-flavored water. During training, only male SHAM rats demonstrated progressively increased intake of Glu/CS^G over Fru/CS^F, and female SHAM rats displayed a trend. RYGB eliminated any difference in single-bottle intake of these solutions during training, regardless of sex. Like their male and female SHAM counterparts, male RYGB rats displayed a conditioned preference for the CS^G-associated stimulus in Tests 1-3. Although female RYGB rats displayed acquisition of the conditioned flavor preference in Test 1, unlike the other groups, when the differential sugar cue between the two solutions was removed in Tests 2 and 3, female rats did not display a CS^G preference. When the sugar and sweetener cues were both removed on Test 4, all groups displayed some generalization decrement. Thus, RYGB does not compromise the ability of rats to learn and express a glucose- vs. fructose-associated conditioned flavor preference when the exact CS used in training is presented in testing. The mechanistic basis for the sex difference in the effect of RYGB on the generalization decrement observed in this type of flavor preference learning warrants further study.

The Problem of Appetite Loss After Major Abdominal Surgery

Objective:

To systematically review the problem of appetite loss after major abdominal surgery.

Summary of Background Data:

Appetite loss is a common problem after major abdominal surgery. Understanding of etiology and treatment options is limited.

Methods:

We searched Medline, Cochrane Central Register of Controlled Trials, and Web of Science for studies describing postoperative appetite loss. Data were extracted to clarify definition, etiology, measurement, surgical influence, pharmacological, and nonpharmacological treatment. PROSPERO registration ID: CRD42021224489.

Results:

Out of 6144 articles, we included 165 studies, 121 of which were also analyzed quantitatively. A total of 19.8% were randomized, controlled trials (n = 24) and 80.2% were nonrandomized studies (n = 97). The studies included 20,506 patients undergoing the following surgeries: esophageal (n = 33 studies), gastric (n = 48), small bowel (n = 6), colon (n = 27), rectal (n = 20), hepatobiliary (n = 6), and pancreatic (n = 13). Appetite was mostly measured with the Quality of Life Questionnaire of the European Organization for Research and Treatment of Cancer (EORTC QLQ C30, n = 54). In a meta-analysis of 4 randomized controlled trials gum chewing reduced time to first hunger by 21.2 hours among patients who had bowel surgery. Other reported treatment options with positive effects on appetite but lower levels of evidence include, among others, intravenous ghrelin administration, the oral Japanese herbal medicine Rikkunshito, oral mosapride citrate, multidisciplin-ary-counseling, and watching cooking shows. No studies investigated the effect of well-known appetite stimulants such as cannabinoids, steroids, or megestrol acetate on surgical patients.

Conclusions:

Appetite loss after major abdominal surgery is common and associated with increased morbidity and reduced quality of life. Recent studies demonstrate the influence of reduced gastric volume and ghrelin secretion, and increased satiety hormone secretion. There are various treatment options available including level IA evidence for postoperative gum chewing. In the future, surgical trials should include the assessment of appetite loss as a relevant outcome measure.

Taste of Fat and Obesity: Different Hypotheses and Our Point of View

Obesity results from a temporary or prolonged positive energy balance due to an alteration in the homeostatic feedback of energy balance. Food, with its discriminative and hedonic qualities, is a key element of reward-based energy intake. An alteration in the brain reward system for highly palatable energy-rich foods, comprised of fat and carbohydrates, could be one of the main factors involved in the development of obesity by increasing the attractiveness and consumption of fat-rich foods. This would induce, in turn, a decrease in the taste of fat. A better understanding of the altered reward system in obesity may open the door to a new era for the diagnosis, management and treatment of this disease.

Behavioral Interventions to Attenuate Driven Overeating and Weight Regain After Bariatric Surgery

Weight regain after bariatric surgery is associated with problematic eating behaviors that have either recurred after a period of improvement or are new-onset behaviors. Problematic eating behaviors after bariatric surgery have been conceptualized in different ways in the literature, such as having a food addiction and experiencing a loss of control of eating. The intersection of these constructs appears to be driven overeating defined as patients' experiences of reduced control of their eating which results in overeating behavior. The purpose of this review is to define patient experiences of driven overeating through the behavioral expression of emotion-based eating, reward-based eating, and executive functioning deficits-namely impulsivity-which is associated with weight regain after having bariatric surgery. Delineating concepts in this way and determining treatment strategies accordingly may reduce distress related to the inevitable return of increased hunger, cravings, portion sizes, and tolerance for highly palatable foods after surgery. Along with standard behavioral weight maintenance strategies, topics including acceptance, motivation, emotion-based eating, reward-based/impulsive eating, physical activity, and self-compassion are discussed. These concepts have been adapted for patients experiencing weight regain after having bariatric surgery and may be particularly helpful in attenuating driven overeating and weight regain.

Olfaction in the context of obesity and diabetes: Insights from animal models to humans

The olfactory system is at the crossroad between sensory processing and metabolic sensing. In addition to being the center of detection and identification of food odors, it is a sensor for most of the hormones and nutrients responsible for feeding behavior regulation. The consequences of modifications in body homeostasis, nutrient overload and alteration of this brain network in the pathological condition of food-induced obesity and type 2 diabetes are still not elucidated. The aim of this review was first to use both humans and animal studies to report on the current knowledge of the consequences of obesity and type 2 diabetes on odorant threshold and olfactory perception including identification discrimination and memory. We then discuss how olfactory processing can be modified by an alteration of the metabolic homeostasis of the organism and available elements on pharmacological treatments that regulate olfaction. We focus on data within the olfactory system but also on the interactions between the olfactory system and other brain networks impacted by metabolic diseases.

A systematic review and meta-analyses of food preference modifications after bariatric surgery

This systematic review and meta-analyses aimed to synthesize evidence of the link between bariatric surgery and changes in food preferences, considering the method of assessment. MEDLINE, Cochrane Library, Web of Science, Cinahl, PsychINFO, ProQuest, and Open grey were searched incorporating two blocks of terms ("Intervention" and "Food Preferences"). Interventional or observational studies involving patients (BMI ≥ 35 kg m^-2 ) with sleeve gastrectomy (SG) or Roux-en-Y Gastric Bypass (RYGB) and a control group were included. Meta-analyses were performed comparing the standardized daily mean percentage energy from proteins, carbohydrates, and lipids between preoperative and postoperative patients. Fifty-seven studies concerning 2,271 patients with RYGB and 903 patients with SG met the inclusion criteria, of which 24 were eligible for meta-analysis. Despite a total reduction in macronutrient intakes, the meta-analyses revealed a postoperative increase in percentage energy from proteins at 12 months (0.24, 95% CI: 0.03, 0.46, {I² } = 73%) and a decrease in percentage energy from fat at 1 month (-0.47, 95% CI: 0.86, 0.09, {I² } = 72%), up to 24 months (-0.20, 95% CI: -0.31, 0.08, {I² } = 0%). In conclusion, the present systematic review and meta-analyses showed changes of food preferences in terms of macronutrient, food selection and, overall food appreciation up to 5 years following bariatric surgery.

Secretin as a Satiation Whisperer With the Potential to Turn into an Obesity-curbing Knight

The obesity pandemic requires effective preventative and therapeutic intervention strategies. Successful and sustained obesity treatment is currently limited to bariatric surgery. Modulating the release of gut hormones is considered promising to mimic bariatric surgery with its beneficial effects on food intake, body weight, and blood glucose levels. The gut peptide secretin was the first molecule to be termed a hormone; nevertheless, only recently has it been established as a legitimate anorexigenic peptide. In contrast to gut hormones that crosstalk with the brain either directly or by afferent neuronal projections, secretin mediates meal-associated brown fat thermogenesis to induce meal termination, thereby qualifying this physiological mechanism as an attractive, peripheral target for the treatment of obesity. In this perspective, it is of pivotal interest to deepen our as yet superficial knowledge on the physiological roles of secretin as well as meal-associated thermogenesis in energy balance and body weight regulation. Of note, the emerging differences between meal-associated thermogenesis and cold-induced thermogenesis must be taken into account. In fact, there is no correlation between these 2 entities. In addition, the investigation of potential effects of secretin in hedonic-driven food intake, bariatric surgery and chronic treatment using suitable application strategies to overcome pharmacokinetic limitations will provide further insight into its potential to influence energy balance. The aim of this article is to review the facts on secretin's metabolic effects, address prevailing gaps in our knowledge, and provide an overview on the opportunities and challenges of the therapeutic potential of secretin in body weight control.

What Is Weight Loss After Bariatric Surgery Expressed in Percentage Total Weight Loss (%TWL)? A Systematic Review

Percentage total weight loss (%TWL) might be better than percentage excess weight loss to express weight loss in bariatric surgery. In this systematic review, performed according to the PRISMA statement, results of laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB) are assessed in %TWL. A total of 13,426 studies were screened and 49 included, reporting data of 24,760 patients. The results show that, despite limiting data, LRYGB is favorable over LSG in terms of weight loss in short-term follow-up. Although recent guidelines recommend to use %TWL when reporting outcome in bariatric surgery, this study shows that there is still insufficient quality data in %TWL, especially on LSG. The use of %TWL as the primary outcome measure in bariatric surgery should be encouraged.

Do Gut Hormones Contribute to Weight Loss and Glycaemic Outcomes after Bariatric Surgery?

Bariatric surgery is an effective intervention for management of obesity through treating dysregulated appetite and achieving long-term weight loss maintenance. Moreover, significant changes in glucose homeostasis are observed after bariatric surgery including, in some cases, type 2 diabetes remission from the early postoperative period and postprandial hypoglycaemia. Levels of a number of gut hormones are dramatically increased from the early period after Roux-en-Y gastric bypass and sleeve gastrectomy—the two most commonly performed bariatric procedures—and they have been suggested as important mediators of the observed changes in eating behaviour and glucose homeostasis postoperatively. In this review, we summarise the current evidence from human studies on the alterations of gut hormones after bariatric surgery and their impact on clinical outcomes postoperatively. Studies which assess the role of gut hormones after bariatric surgery on food intake, hunger, satiety and glucose homeostasis through octreotide use (a non-specific inhibitor of gut hormone secretion) as well as with exendin 9–39 (a specific glucagon-like peptide-1 receptor antagonist) are reviewed. The potential use of gut hormones as biomarkers of successful outcomes of bariatric surgery is also evaluated.

Changes of Taste, Smell and Eating Behavior in Patients Undergoing Bariatric Surgery: Associations with PROP Phenotypes and Polymorphisms in the Odorant-Binding Protein OBPIIa and CD36 Receptor Genes

Bariatric surgery is the most effective long-term treatment for severe obesity and related comorbidities. Although patients who underwent bariatric surgery report changes of taste and smell perception, results from sensory studies are discrepant and limited. Here, we assessed taste and smell functions in 51 patients before, one month, and six months after undergoing bariatric surgery. We used taste strip tests to assess gustatory function (including sweetness, saltiness, sourness, umaminess, bitterness and oleic acid, a fatty stimulus), the “Sniffin’ Sticks” test to assess olfactory identification and the 3-Factor Eating Questionnaire to assess eating behavior. We also explored associations between these phenotypes and flavor-related genes. Results showed an overall improvement in taste function (including increased sensitivity to oleic acid and the bitterness of 6-n-propylthiouracil (PROP)) and in olfactory function (which could be related to the increase in PROP and oleic acid sensitivity), an increase in cognitive restraint, and a decrease in disinhibition and hunger after bariatric surgery. These findings indicate that bariatric surgery can have a positive impact on olfactory and gustatory functions and eating behavior (with an important role of genetic factors, such PROP tasting), which in turn might contribute to the success of the intervention.

Brain-gut-microbiome interactions in obesity and food addiction

Normal eating behaviour is coordinated by the tightly regulated balance between intestinal and extra-intestinal homeostatic and hedonic mechanisms. By contrast, food addiction is a complex, maladaptive eating behaviour that reflects alterations in brain-gut-microbiome (BGM) interactions and a shift of this balance towards hedonic mechanisms. Each component of the BGM axis has been implicated in the development of food addiction, with both brain to gut and gut to brain signalling playing a role. Early-life influences can prime the infant gut microbiome and brain for food addiction, which might be further reinforced by increased antibiotic usage and dietary patterns throughout adulthood. The ubiquitous availability and marketing of inexpensive, highly palatable and calorie-dense food can further shift this balance towards hedonic eating through both central (disruptions in dopaminergic signalling) and intestinal (vagal afferent function, metabolic endotoxaemia, systemic immune activation, changes to gut microbiome and metabolome) mechanisms. In this Review, we propose a systems biology model of BGM interactions, which incorporates published reports on food addiction, and provides novel insights into treatment targets aimed at each level of the BGM axis.

COVID-19 and Obesity: Is Bariatric Surgery Protective? Retrospective Analysis on 2145 Patients Undergone Bariatric-Metabolic Surgery from High Volume Center in Italy (Lombardy)

INTRODUCTION

On February 20, 2020, a severe case of pneumonia due to SARS-CoV-2 was diagnosed in northern Italy (Lombardy). Some studies have identified obesity as a risk factor for severe disease in patients with COVID-19. The purpose of this study was to investigate the incidence of SARS-CoV-2 infection and its severity in patients who have undergone bariatric surgery.

MATERIAL AND METHODS

During the lockdown period (until May 2020), we contacted operated patients by phone and social networks (e.g., Facebook) to maintain constant contact with them; in addition, we gave the patients a dedicated phone number at which to call us for emergencies. We produced telemedicine and educational videos for obese and bariatric patients, and we submitted a questionnaire to patients who had undergone bariatric surgery in the past.

RESULTS

A total of 2145 patients (313 male; 1832 female) replied to the questionnaire. Mean presurgical BMI: 44.5 ± 6.8 kg/m². Mean age: 44.0 ± 10.0 year. Mean BMI after surgery: 29.3 ± 5.5 kg/m² (p < 0.05). From February to May 2020, 8.4% of patients reported that they suffered from at least one symptom among those identified as related to SARS-CoV-2 infection. Thirteen patients (0.6%) tested positive for COVID-19. Six patients (0.3%) were admitted to the COVID Department, and 2 patients (0.1%) were admitted to the ICU.

CONCLUSIONS

Although the reported rates of symptoms and fever were high, only 0.6% of patients tested positive for COVID-19. Among more than 2000 patients who underwent bariatric surgery analyzed in this study, only 0.1% needed ICU admission.

The Implication of Gut Hormones in the Regulation of Energy Homeostasis and Their Role in the Pathophysiology of Obesity

PURPOSE OF REVIEW

This review provides an update on the role of gut hormones and their interactions in the regulation of energy homeostasis, describes gut hormone adaptations in obesity and in response to weight loss, and summarizes the current evidence on the role of gut hormone-based therapies for obesity treatment.

RECENT FINDINGS

Gut hormones play a key role in regulating eating behaviour, energy and glucose homeostasis. Dysregulated gut hormone responses have been proposed to be pathogenetically involved in the development and perpetuation of obesity. Summarizing the major gut hormone changes in obesity, obese individuals are characterized by blunted postprandial ghrelin suppression, loss of premeal ghrelin peaks, impaired diurnal ghrelin variability and reduced fasting and postprandial levels of anorexigenic peptides. Adaptive alterations of gut hormone levels are implicated in weight regain, thus complicating hypocaloric dietary interventions, and can further explain the profound weight loss and metabolic improvement following bariatric surgery. A plethora of compounds mimicking gut hormone changes after bariatric surgery are currently under investigation, introducing a new era in the pharmacotherapy of obesity. The current trend is to combine different gut hormone receptor agonists and target multiple systems simultaneously, in order to replicate as closely as possible the gut hormone milieu after bariatric surgery and circumvent the counter-regulatory adaptive changes associated with dietary energy restriction. An increasing number of preclinical and early-phase clinical trials reveal the additive benefits obtained with dual or triple gut peptide receptor agonists in reducing body weight and improving glycaemia. Gut hormones act as potent regulators of energy and glucose homeostasis. Therapeutic strategies targeting their levels or receptors emerge as a promising approach to treat patients with obesity and hyperglycaemia.

Diet approach before and after bariatric surgery

Bariatric surgery (BS) is today the most effective therapy for inducing long-term weight loss and for reducing comorbidity burden and mortality in patients with severe obesity. On the other hand, BS may be associated to new clinical problems, complications and side effects, in particular in the nutritional domain. Therefore, the nutritional management of the bariatric patients requires specific nutritional skills. In this paper, a brief overview of the nutritional management of the bariatric patients will be provided from pre-operative to post-operative phase. Patients with severe obesity often display micronutrient deficiencies when compared to normal weight controls. Therefore, nutritional status should be checked in every patient and correction of deficiencies attempted before surgery. At present, evidences from randomized and retrospective studies do not support the hypothesis that pre-operative weight loss could improve weight loss after BS surgery, and the insurance-mandated policy of a preoperative weight loss as a pre-requisite for admission to surgery is not supported by medical evidence. On the contrary, some studies suggest that a modest weight loss of 5-10% in the immediate preoperative period could facilitate surgery and reduce the risk of complications. Very low calories diet (VLCD) and very low calories ketogenic diets (VLCKD) are the most frequently used methods for the induction of a pre-operative weight loss today. After surgery, nutritional counselling is recommended in order to facilitate the adaptation of the eating habits to the new gastro-intestinal physiology. Nutritional deficits may arise according to the type of bariatric procedure and they should be prevented, diagnosed and eventually treated. Finally, specific nutritional problems, like dumping syndrome and reactive hypoglycaemia, can occur and should be managed largely by nutritional manipulation. In conclusion, the nutritional management of the bariatric patients requires specific nutritional skills and the intervention of experienced nutritionists and dieticians.

Consequences of Obesity on the Sense of Taste: Taste Buds as Treatment Targets?

Premature obesity-related mortality is caused by cardiovascular and pulmonary diseases, type 2 diabetes mellitus, physical disabilities, osteoarthritis, and certain types of cancer. Obesity is caused by a positive energy balance due to hyper-caloric nutrition, low physical activity, and energy expenditure. Overeating is partially driven by impaired homeostatic feedback of the peripheral energy status in obesity. However, food with its different qualities is a key driver for the reward driven hedonic feeding with tremendous consequences on calorie consumption. In addition to visual and olfactory cues, taste buds of the oral cavity process the earliest signals which affect the regulation of food intake, appetite and satiety. Therefore, taste buds may play a crucial role how food related signals are transmitted to the brain, particularly in priming the body for digestion during the cephalic phase. Indeed, obesity development is associated with a significant reduction in taste buds. Impaired taste bud sensitivity may play a causal role in the pathophysiology of obesity in children and adolescents. In addition, genetic variation in taste receptors has been linked to body weight regulation. This review discusses the importance of taste buds as contributing factors in the development of obesity and how obesity may affect the sense of taste, alterations in food preferences and eating behavior.

Revisiting the Ghrelin Changes Following Bariatric and Metabolic Surgery

Since the description of ghrelin in 1999, several studies have dug into the effects of this hormone and its relationship with bariatric surgery. While some aspects are still unresolved, a clear connection between ghrelin and the changes after metabolic surgery have been established. Besides weight loss, a significant amelioration in obesity-related comorbidities following surgery has also been reported. These changes in patients occur in the early postoperative period, before the weight loss appears, so that amelioration may be mainly due to hormonal changes. The purpose of this review is to go through the current body of knowledge of ghrelin's physiology, as well as to update and clarify the changes that take place in ghrelin concentrations following bariatric/metabolic surgery together with their potential consolidation to outcomes.

Missing Something? Comparisons of Effectiveness and Outcomes of Bariatric Surgery Procedures and Their Preferred Reporting: Refining the Evidence Base

Comparisons of effectiveness of bariatric surgery (BS) procedures encompass weight loss, metabolic/clinical outcomes, and improvements or worsening of comorbidities. Post-operative physical activity (PA) and diet influence such outcomes but are frequently not included in comparisons of effectiveness. We assessed the value and necessity of including post-operative PA/diet data when comparing effectiveness of BS. Including post-operative PA/diet data has significant benefits for BS and patients. The paper proposes an explicit preferred reporting system (Preferred REporting of post-operative PHYsical activity and Diet data in comparisons of BS effectiveness: PRE-PHYD Bariatric). Including post-operative PA/diet data could result in more accurate appraisals of effectiveness of BS procedures. This could translate into better 'individualized' BS by achieving a better 'fit' between patient and procedure.

Alteration Pattern of Taste Perception After Bariatric Surgery: a Systematic Review of Four Taste Domains

BACKGROUND

Efforts continue to understand the underlying mechanism of weight loss after bariatric surgery. Taste perception has shown to be a contributing factor. However, the alteration pattern in different taste domains and among bariatric procedures has not been sufficiently investigated.

OBJECTIVES

To study the alteration pattern in the perception of four taste domains after different bariatric procedures.

SETTINGS

Private Research Institute, USA.

METHODS

A systematic review was conducted to pool available data in the literature on post-operative changes in the perception of sensitivity to four taste domains after Roux-en-Y gastric bypass (RYGB), laparoscopic sleeve gastrectomy (LSG), and adjustable gastric banding (AGB).

RESULTS

Our study showed that bariatric surgery is associated with significant change in sensitivity to all four taste domains especially salt taste, sweetness, and sourness. LSG patients showed an increased sensitivity to all four taste domains. However, RYGB patients had a variable alteration pattern of taste perception but more commonly a decreased sensitivity to sweetness and an increased sensitivity to salt taste and sourness. Additionally, AGB patients had a decreased sensitivity to sweetness, salt taste, and sourness.

CONCLUSION

Bariatric surgery is associated with taste change in a way which results in less preference for high-calorie food and possibly reduced calorie intake. This may explain one of the mechanisms by which bariatric surgery produces weight loss. However, data are heterogeneous, the potential effect dilutes over time, and the alteration varies significantly between different procedures.

Pre-operative Restraint and Post-operative Hunger, Disinhibition and Emotional Eating Predict Weight Loss at 2 Years Post-laparoscopic Adjustable Gastric Banding

INTRODUCTION

A principal mechanism of action in bariatric surgery is reduction in calorie consumption due to decreased hunger and increased satiety. Patients' ability to perceive post-operative changes to their hunger is therefore central to optimal results. This study examined factors that may impact how patients perceive post-operative hunger and how perception of hunger impacts eating and subsequent weight loss after laparoscopic adjustable gastric banding (LAGB).

METHODS

Patients undertaking LAGB (n = 147) provided pre-surgery and 2-year weight loss data and pre-surgery and 12-month psychological data (perception of hunger, disinhibition related to eating, emotional eating).

RESULTS

Path analysis demonstrated that patients with lower levels of pre-surgery cognitive restraint over eating experienced significantly greater reduction in perception of hunger at 12 months post-surgery. Perceived reduction in hunger was significantly associated with lower levels of both emotional eating and disinhibited eating. Finally, reduced emotional eating at 12 months significantly predicted 9% of the variance in percentage of total weight loss (%TWL) at 2 years after surgery.

CONCLUSION

These initial findings suggest that preparation for bariatric surgery may be enhanced by psychoeducation regarding cognitive restraint over eating and its effect on hunger perception. In addition, psychological treatment that focuses on identifying and responding to changes in hunger may contribute to improved outcomes for those who have difficulty adjusting to post-operative eating behaviours.

Weight Loss, Dietary Preferences, and Reduction in the Sense of Smell with the Use of a Novel Nasal Device

INTRODUCTION

Exposure to food odors are known to increase food intake. Olfaction declines from age 50 years.

OBJECTIVE

We examined changes in the sense of smell, body weight, food preferences, and parameters of metabolic status, following the use of a specially designed nasal device.

METHODS

This is a randomized, placebo-controlled study. Participants wore a nasal device (soft silicone insert) for 5-12 h daily (device group) or inserted 2 drops of normal saline into each nostril daily (control group). Follow-up visits occurred every 2 weeks. All participants were given a 500 kcal/day reduced diet and instructed not to change their regular physical activity. Weight, food preferences, olfactory sensitivity, and blood tests were performed at baseline and after 12 weeks.

RESULTS

Of 156 participants, 65 (42%) completed the study. Sense of smell decreased in the device group (from 6.4 ± 0.9 to 4.4 ± 1.5, on a scale of 0-7, p < 0.001), and did not change in the control group. Weight loss decreased by 6.6 ± 3.7% (p = 0.001) and by 5.7 ± 3.5% (p = 0.001) in the respective groups (between-group difference, p > 0.05). Among participants aged ≤50 years, weight loss was greater in the device than in the control group (7.7 ± 4.2% vs. 4.1 ± 2.9%, p = 0.02). Insulin level and the homeostatic model assessment of insulin resistance (HOMA-IR) were significantly reduced in the device group (p = 0.02 and p = 0.01, respectively), but not in the control group. Food preferences for sugar (p < 0.02), sweet beverages (p < 0.001), and artificial sweeteners (p < 0.02) were significantly reduced in the device group compared to the control group.

CONCLUSIONS

The use of a novel self-administrated nasal device led to reduced olfactory sensitivity, improved insulin sensitivity, weight loss, and lesser preference for sweets in adults aged ≤50 years.

Alcohol consumption after laparoscopic sleeve gastrectomy: 1-year results

INTRODUCTION

Laparoscopic sleeve gastrectomy (SG) represents, at present, the most performed bariatric procedure worldwide with excellent long-term results on weight loss and comorbidities control. After the gastrectomy procedure, together with hormonal modification, several changes in taste and habits occur, including the potential modification in alcohol consumption. The aim of this prospective study was to determine the frequency and the amount of alcohol use before and after SG using a modified version of the Alcohol Use Disorder Identification Test (AUDIT) at 1-year follow-up and eventually to evaluate relationships between different ages and sexes.

MATERIALS AND METHODS

A total of 142 patients were prospectively enrolled and evaluated before and 1 year after SG with a modified AUDIT. The exclusion criteria were as follows: history of alcohol abuse, presence of psychopathology or cognitive impairments, diabetes mellitus type II decompensated, or previous gastrointestinal, liver, and pancreatic resective surgery. Subgroup analyses were performed between male and female and between under and over 40 years old.

RESULTS

The median AUDIT score decreased from 2.70 (range 1-18) before surgery to 1.38 (range 1-7) after 1 year of SG, indicating a marked reduction in alcohol use. The most consumed alcoholic drink was beer (36.6%/n = 52) while after surgery the consumption of beer decreased considerably (21.1%/n = 30). The frequency of alcohol consumption also decreased: at baseline 45% of patients consumed alcoholic drinks "from 2 to 4 times per month", whereas 26 and 39.4% consumed alcohol "never" and "less than once a month," respectively. After surgery, nobody consumed more then six alcoholic drinks. No differences were found between the subgroups in terms of alcohol consumption and social behavior.

CONCLUSIONS

The alcohol preference is modified and decreased 1 year after SG and this could be related to the strict nutritional follow-up and to the hormonal changes. Studies with large samples and long-term follow-up are needed to confirm our data.

LEVEL OF EVIDENCE

IV.

Bariatric Surgery Leads to Short-Term Effects on Sweet Taste Sensitivity and Hedonic Evaluation of Fatty Food Stimuli

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.

RYGB and flavor-consequence learning

Flavor-consequence learning refers to learned associations between flavor stimuli and post-oral consequences of food that affect food selection, amount eaten and affect. Forms of flavor-consequence learning include flavor aversions, flavor avoidance, conditioned satiety, expected satiety and appetition. Roux-en-Y gastric bypass surgery (RYGB) and other bariatric procedures alter gastrointestinal processing of food in a number of ways. Thus, it is plausible that these procedures alter post-oral unconditioned stimuli that support flavor-consequence learning, leading to altered food selection, amount eaten, and affect. Surprisingly, however, there is almost no research on the role of flavor-consequence learning in the effects of bariatric surgery on appetite. This issue urgently warrants investigation.

Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on Food Preferences and Potential Mechanisms Involved

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

Changes in taste function and ingestive behavior following bariatric surgery

Bariatric surgery is the most effective treatment for severe obesity and its related comorbidities. Roux-en-Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) are currently the most popular weight-loss surgeries used worldwide. Following these surgeries, many patients self-report changes in taste perception and decreased preference for unhealthy foods. These reported changes might account for increased adherence to healthier diets and successful weight loss after surgeries. However, researchers have used a variety of methodologies to assess patients' reported changes andresults are discrepant. The goal of this review is to summarize the literature regarding changes to taste function and ingestive behavior following RYGB and SG to examine differences in findings by methodology (indirect vs. direct measurements). We focused our review around changes in sweets, fats, and alcohol because most of the documented changes in ingestive behavior post-surgery are related to changes in these dietary items. We found that studies using surveys and questionnaires generally find that subjects self-report changes in taste and decrease their preference and cravings for energy-dense foods (particularly, sweets and high-fats). However, studies using validated sensory techniques that include oral sampling or by using direct food intake measurements find little to no change in subjects' ability to perceive taste or their preference for energy-dense foods. Therefore, reported changes in taste and food preferences are unlikely to be explained by alterations in taste intensity and diet selection, and are rather related to changes in the rewarding value of food. Further, that RYGB, and likely SG, is associated with increased alcohol consumption and arisk to develop an alcohol use disorder) supports the notion that these surgeries alter central circuits of reward that are critical in the regulation of ingestive behavior.

Does taste preference predict weight regain after bariatric surgery?

BACKGROUND

While bariatric surgery is well established as a means of inducing sustained weight loss, the rate of weight loss typically declines after a year, and weight regain has been observed. Preoperative taste preferences have been suspected to play a role in weight regain, possibly by influencing post-operative dietary practices. We sought to investigate the association between preoperative taste preferences and weight regain following bariatric surgery.

METHODS

Patients who underwent bariatric surgery with at least 2 years of follow-up were included. Demographics and weight were collected in follow-up visits; while patient recall of preoperative taste preference was assessed, using a multiple-choice question in the study survey administered at least 6 months post-surgery. Weight regain was calculated as weight at 2 years minus weight at 1 year post-surgery, with weight regain denoted by positive values and weight loss by negative. Linear regression models were utilized to study associations between weight regain and preoperative taste preferences with and without adjusting for demographic factors and surgery type.

RESULTS

Patients undergoing RYGB had less weight regain (- 4.5 kg, p = 0.033) compared to patients undergoing VSG. Compared to patients with no preferences, patients with sweet food or salty food preferences had 5.5 kg (p = 0.038) and 6.1 kg (p = 0.048) weight regain, respectively, at 2 years post-surgery. After adjustment, patients with salty food preference had 6.8 kg (p = 0.027) weight regain compared to patients with no preferences.

CONCLUSIONS

Preoperative salty taste preference was associated with weight regain at 2 years post-surgery in patients undergoing bariatric surgery. Findings of this project might have implications for predicting long-term weight loss maintenance for patients with known preoperative taste preferences. Our study suggests that patients with preoperative salty taste preference may need further post-operative psychosocial support and resources to prevent weight regain and to ensure healthy and sufficient weight loss.

Mechanisms for the metabolic success of bariatric surgery

To date, bariatric surgery remains the most effective strategy for the treatment of obesity and its comorbidities. However, given the enormity of the obesity epidemic, and sometimes variable results, it is not a feasible strategy for the treatment of all obese patients. A simple PubMed search for 'bariatric surgery' reveals over 28 000 papers that have been published since the 1940s when the first bariatric surgeries were performed. However, there is still an incomplete understanding of the mechanisms for the weight loss and metabolic success of surgery. An understanding of the mechanisms is important because it may lead to greater understanding of the pathophysiology of obesity and thus surgery-alternative strategies for the treatment of all obese patients. In this review, the potential mechanisms that underlie the success of surgery are discussed, with a focus on the potential endocrine, neural and other circulatory factors (eg, bile acids) that have been proposed to play a role.

Associations between Weight Loss, Food Likes, Dietary Behaviors, and Chemosensory Function in Bariatric Surgery: A Case-Control Analysis in Women

We tested the hypothesis that successful weight loss post-bariatric surgery would be associated with healthier chemosensory function, food likes, and dietary behaviors than either unsuccessful weight loss or pre-surgery morbid obesity. In a case-control design, pre-surgical women with morbid obesity (n = 49) were compared with those 1-year post-surgery (24 Roux-en-Y Bypass, 24 Sleeve Gastrectomy) and defined by excess or percent weight loss as successful/unsuccessful. For self-reported smell/taste perception, more post-surgery than pre-surgery reported improved/distorted perception, especially if weight loss successful. Measured taste function (perceived quinine and NaCl intensity) was lower among weight loss unsuccessful versus pre-surgery patients, yet a genetic variation in taste probe (propylthiouracil bitterness) matched expected frequencies without significant pre/post-surgery difference. Regarding survey-reported liking, higher diet quality was seen in the weight loss successful (independent of surgery type) versus pre-surgical patients, with differences driven by lower sweet and refined carbohydrate liking. The post versus pre-surgical patients had greater restraint but less hunger and disinhibition. Patients reporting both higher diet quality and lower hunger showed greater % weight loss, independent of surgery type. Thus, successful weight loss 1-year post-bariatric surgery was associated with improved or distorted chemosensation and patterns of liking associated with healthier diets, especially if coupled with less hunger.