Shifts in Food Preferences After Bariatric Surgery: Observational Reports and Proposed Mechanisms

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.

Mechanisms of bariatric surgery for weight loss and diabetes remission

Obesity and type 2 diabetes(T2D) lead to defects in intestinal hormones secretion, abnormalities in the composition of bile acids (BAs), increased systemic and adipose tissue inflammation, defects of branched-chain amino acids (BCAAs) catabolism, and dysbiosis of gut microbiota. Bariatric surgery (BS) has been shown to be highly effective in the treatment of obesity and T2D, which allows us to view BS not simply as weight-loss surgery but as a means of alleviating obesity and its comorbidities, especially T2D. In recent years, accumulating studies have focused on the mechanisms of BS to find out which metabolic parameters are affected by BS through which pathways, such as which hormones and inflammatory processes are altered. The literatures are saturated with the role of intestinal hormones and the gut-brain axis formed by their interaction with neural networks in the remission of obesity and T2D following BS. In addition, BAs, gut microbiota and other factors are also involved in these benefits after BS. The interaction of these factors makes the mechanisms of metabolic improvement induced by BS more complicated. To date, we do not fully understand the exact mechanisms of the metabolic alterations induced by BS and its impact on the disease process of T2D itself. This review summarizes the changes of intestinal hormones, BAs, BCAAs, gut microbiota, signaling proteins, growth differentiation factor 15, exosomes, adipose tissue, brain function, and food preferences after BS, so as to fully understand the actual working mechanisms of BS and provide nonsurgical therapeutic strategies for obesity and T2D.

Sleeve Gastrectomy-Induced Body Mass Index Reduction Increases the Intensity of Taste Perception's and Reduces Bitter-Induced Pleasantness in Severe Obesity

Background: The sense of taste is involved in food behavior and may drive food choices, likely contributing to obesity. Differences in taste preferences have been reported in normal-weight as compared to obese subjects. Changes in taste perception with an increased sweet-induced sensitivity have been reported in surgically treated obese patients, but data regarding the perception of basic tastes yielded conflicting results. We aimed to evaluate basic taste identification, induced perception, and pleasantness in normal-weight controls and obese subjects before and after bariatric surgery. Methods: Severe obese and matched normal weight subjects underwent a standardized spit test to evaluate sweet, bitter, salty, umami, and sour taste identification, induced perception, and pleasantness. A subset of obese subjects were also studied before and 12 months after sleeve gastrectomy. Results: No significant differences in basic taste-induced perceptions were observed, although a higher number of controls correctly identified umami than did obese subjects. Sleeve-gastrectomy-induced weight loss did not affect the overall ability to correctly identify basic tastes but was associated with a significant increase in taste intensities, with higher scores for sour and bitter, and a significantly reduced bitter-induced pleasantness. Conclusions: The perception of basic tastes is similar in normal-weight and severely obese subjects. Sleeve-gastrectomy-induced weight loss significantly increases basic taste-induced intensity, and selectively reduces bitter-related pleasantness without affecting the ability to identify the tastes. Our findings reveal that taste perception is influenced by body mass index changes, likely supporting the hypothesis that centrally mediated mechanisms modulate taste perception in severe obesity.

Oromotor and somatic taste reactivity during sucrose meals reveals internal state and stimulus palatability after gastric bypass in rats

After Roux-en-Y gastric bypass (RYGB), rats consume less high-energy foods and fluids, though whether this reflects a concomitant change in palatability remains unclear. By measuring behavior during intraorally delivered liquid meals across days (1 water, 8 sucrose sessions), we showed that RYGB rats (RYGB, n = 8/sex) consumed less 1.0 M sucrose than their sham surgery counterparts (SHAM, n = 8 males, n = 11 females) but displayed similarly high levels of ingestive taste reactivity responses at the start of infusions. Relative to water, both groups increased intake of sucrose, and ingestive responses were dominated by tongue protrusions rather than mouth movements. Thus, RYGB animals still found sucrose palatable despite consuming less than the SHAM group. As the intraoral infusion progressed but before meal termination, aversive behavior remained low and both RYGB and SHAM animals showed fewer ingestive responses, predominantly mouth movements as opposed to tongue protrusions. This shift in responsiveness unrelated to surgical manipulation suggests negative alliesthesia, or a decreased palatability, as rats approach satiation. Notably, only in RYGB rats, across sessions, there was a striking emergence of aversive behavior immediately after the sucrose meal. Thus, although lower intake in RYGB rats seems independent of the hedonic taste properties of sucrose, taste reactivity behavior in these animals immediately after termination of a liquid meal appears to be influenced by postoral events and reflects a state of nimiety or excessive consumption. Measurement of taste reactivity behaviors during an intraorally delivered meal represents a promising way to make inferences about internal state in nonverbal preclinical models.

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.

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.

A Comparison of Total Food Intake at a Personalised Buffet in People with Obesity, before and 24 Months after Roux-en-Y-Gastric Bypass Surgery

Long-term reductions in the quantity of food consumed, and a shift in intake away from energy dense foods have both been implicated in the potent bariatric effects of Roux-en-Y gastric bypass (RYGB) surgery. We hypothesised that relative to pre-operative assessment, a stereotypical shift to lower intake would be observed at a personalised ad libitum buffet meal 24 months after RYGB, driven in part by decreased selection of high energy density items. At pre-operative baseline, participants (n = 14) rated their preference for 72 individual food items, each of these mapping to one of six categories encompassing high and low-fat choices in combination with sugar, complex carbohydrate or and protein. An 18-item buffet meal was created for each participant based on expressed preferences. Overall energy intake was reduced on average by 60% at the 24-month buffet meal. Reductions in intake were seen across all six food categories. Decreases in the overall intake of all individual macronutrient groups were marked and were generally proportional to reductions in total caloric intake. Patterns of preference and intake, both at baseline and at follow-up appear more idiosyncratic than has been previously suggested by verbal reporting. The data emphasise the consistency with which reductions in ad libitum food intake occur as a sequel of RYGB, this being maintained in the setting of a self-selected ad libitum buffet meal. Exploratory analysis of the data also supports prior reports of a possible relative increase in the proportional intake of protein after RYGB.

Meal Patterns and Food Choices of Female Rats Fed a Cafeteria-Style Diet Are Altered by Gastric Bypass Surgery

After Roux-en-Y gastric bypass surgery (RYGB), rats tend to reduce consumption of high-sugar and/or high-fat foods over time. Here, we sought to investigate the behavioral mechanisms underlying these intake outcomes. Adult female rats were provided a cafeteria diet comprised of five palatable foodstuffs varying in sugar and fat content and intake was monitored continuously. Rats were then assigned to either RYGB, or one of two control (CTL) groups: sham surgery or a nonsurgical control group receiving the same prophylactic iron treatments as RYGB rats. Post-sur-gically, all rats consumed a large first meal of the cafeteria diet. After the first meal, RYGB rats reduced intake primarily by decreasing the meal sizes relative to CTL rats, ate meals more slowly, and displayed altered nycthemeral timing of intake yielding more daytime meals and fewer nighttime meals. Collectively, these meal patterns indicate that despite being motivated to consume a cafeteria diet after RYGB, rats rapidly learn to modify eating behaviors to consume foods more slowly across the entire day. RYGB rats also altered food preferences, but more slowly than the changes in meal patterns, and ate proportionally more energy from complex carbohydrates and protein and proportionally less fat. Overall, the pattern of results suggests that after RYGB rats quickly learn to adjust their size, eating rate, and distribution of meals without altering meal number and to shift their macronutrient intake away from fat; these changes appear to be more related to postingestive events than to a fundamental decline in the palatability of food choices.

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.

Methodological issues in assessing change in dietary intake and appetite following gastric bypass surgery: A systematic review

Gastric bypass surgery is an effective long-term treatment for individuals with severe obesity. Changes in appetite, dietary intake, and food preferences have all been postulated to contribute to postoperative body weight regulation, however, findings are inconsistent. The aim of this systematic review was to evaluate the current literature on changes in dietary intake and appetite following gastric bypass surgery, in the context of the methodology used and the analysis, interpretation, and presentation of results. Four databases were systematically searched with terms related to "gastric bypass surgery," "appetite," and "dietary intake," and 49 papers (n = 2384 patients after gastric bypass) were eligible for inclusion. The evidence indicated that only a reduction in overall energy intake and an increase in postprandial satiety are maintained beyond 6-month post-surgery, whereas relative macronutrient intake and premeal hunger remain unchanged. However, available data were limited by inconsistencies in the methods, analysis, presentation, and interpretation of results. In particular, there was a reliance on data collected by subjective methods with minimal acknowledgment of the limitations, such as misreporting of food intake. There is a need for further work employing objective measurement of appetite and dietary intake following gastric bypass surgery to determine how these mechanisms may contribute to weight regulation in the longer term.

Factors Associated with Favorable Changes in Food Preferences After Bariatric Surgery

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.

Gastric bypass in female rats lowers concentrated sugar solution intake and preference without affecting brief-access licking after long-term sugar exposure

In rodents, Roux-en-Y gastric bypass (RYGB) decreases intake of, and preference for, foods or fluids that are high in sugar. Whether these surgically induced changes are due to decreases in the palatability of sugar stimuli is controversial. We used RYGB and sham-operated (SHAM) female rats to test the influence of prolonged ingestive experience with sugar solutions on the motivational potency of these stimuli to drive licking in brief-access (BA) tests. In experiment 1, RYGB attenuated intake of, and caloric preference for, 0.3 M sucrose during five consecutive, 46-h two-bottle tests (TBTs; sucrose). A second series of TBTs (5 consecutive, 46-h tests) with 1.0 M sucrose revealed similar results, except fluid preference for 1.0 M sucrose also significantly decreased. Before, between, and after the two series of TBTs, two sessions of BA tests (30 min; 10-s trials) with an array of sucrose concentrations (0 and 0.01-1.0 M) were conducted. Concentration-dependent licking and overall trial initiation did not differ between surgical groups in any test. In a similar experimental design in a second cohort of female rats, 0.6 and 2.0 M glucose (isocaloric with sucrose concentrations in experiment 1) were used in the TBTs; 0 and 0.06-2.0 M glucose were used in the BA tests. Outcomes were similar to those for experiment 1, except RYGB rats initiated fewer trials during the BA tests. Although RYGB profoundly affected intake of, and caloric preference for, sugar solutions and, with high concentrations, fluid preference, RYGB never influenced the motivational potency of sucrose or glucose to drive concentration-dependent licking in BA tests.

Gut Microbiota Profile of Obese Diabetic Women Submitted to Roux-en-Y Gastric Bypass and Its Association with Food Intake and Postoperative Diabetes Remission

Gut microbiota composition is influenced by environmental factors and has been shown to impact body metabolism. Objective: To assess the gut microbiota profile before and after Roux-en-Y gastric bypass (RYGB) and the correlation with food intake and postoperative type 2 diabetes remission (T2Dr). Design: Gut microbiota profile from obese diabetic women was evaluated before (n = 25) and 3 (n = 20) and 12 months (n = 14) after RYGB, using MiSeq Illumina-based V4 bacterial 16S rRNA gene profiling. Data on food intake (7-day record) and T2Dr (American Diabetes Association (ADA) criteria) were recorded. Results: Preoperatively, the abundance of five bacteria genera differed between patients with (57%) and without T2Dr (p < 0.050). Preoperative gut bacteria genus signature was able to predict the T2Dr status with 0.94 accuracy ROC curve (receiver operating characteristic curve). Postoperatively (vs. preoperative), the relative abundance of some gut bacteria genera changed, the gut microbial richness increased, and the Firmicutes to Bacteroidetes ratio (rFB) decreased (p < 0.05) regardless of T2Dr. Richness levels was correlated with dietary profile pre and postoperatively, mainly displaying positive and inverse correlations with fiber and lipid intakes, respectively (p < 0.05). Conclusions: Gut microbiota profile was influenced by RYGB and correlated with diet and T2Dr preoperatively, suggesting the possibility to assess its composition to predict postoperative T2Dr.

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.

IS THERE ANY CHANGE IN PHENOTYPIC CHARACTERISTICS COMPARING 5 TO 10 YEARS OF FOLLOW-UP IN OBESE PATIENTS UNDERGOING ROUX-EN-Y GASTRIC BYPASS?

Background

: Bariatric surgery promotes significant weight loss and improvement of associated comorbidities; however, nutrients deficiencies and weight regain may occur in the middle-late postoperative period.

Aim:

To investigate nutritional status in 10 years follow-up.

Methods

: Longitudinal retrospective study in which anthropometric, biochemical indicators and nutritional intake were assessed before and after one, two, three, four, five and ten years of Roux-en Y gastric bypass through analysis of medical records.

Results

: After ten years there was a reduction of 29.2% of initial weight; however, 87.1% of patients had significant weight regain. Moreover, there was an increase of incidence of iron (9.2% to 18.5%), vitamin B12 (4.2% to 11.1%) and magnesium deficiency (14.1% to 14.8%). Folic acid concentrations increased and the percentage of individuals with glucose (40.4% to 3.7%), triglycerides (38% to 7.4%), HDL cholesterol (31 % to 7.4%) and uric acid (70.5% to 11.1%) abnormalities reduced. Also, there is a reduction of food intake at first year postoperative. After 10 years, there was an increase in energy, protein and lipid intake, also a reduction in folid acid intake.

Conclusions

: Roux-en Y gastric bypass is an effective procedure to promote weight loss and improve comorbidities associated with obesity. However, comparison between postoperative period of five and 10 years showed a high prevalence of minerals deficiency and a significant weight regain, evidencing the need for nutritional follow-up in the postoperative period.

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.

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.

Bariatric Surgery Does Not Affect Food Preferences, but Individual Changes in Food Preferences May Predict Weight Loss

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 < 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).

CONCLUSIONS

RYGB surgery and SG surgery do not affect food preferences. However, changes in food preferences seem to be predictive of weight loss.