Relative Reinforcing Value of Energy-dense Snack Foods: In Overweight and Obese Adults

Transcranial Magnetic Stimulation for Reducing the Relative Reinforcing Value of Food in Adult Patients With Obesity Pursuing Metabolic and Bariatric Surgery: Protocol for a Pilot, Within-Participants, Sham-Controlled Trial

BACKGROUND

Metabolic and bariatric surgery (MBS) is the most effective and durable obesity treatment. However, there is heterogeneity in weight outcomes, which is partially attributed to variability in appetite and eating regulation. Patients with a strong desire to eat in response to the reward of palatable foods are more likely to overeat and experience suboptimal outcomes. This subgroup, classified as at risk, may benefit from repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique that shows promise for reducing cravings and consumption of addictive drugs and food; no study has evaluated how rTMS affects the reinforcing value of food and brain reward processing in the context of MBS.

OBJECTIVE

The goal of the Transcranial Magnetic Stimulation to Reduce the Relative Reinforcing Value of Food (RESTRAIN) study is to perform an initial rTMS test on the relative reinforcing value (RRV) of food (the reinforcing value of palatable food compared with money) among adult patients who are pursuing MBS and report high food reinforcement. Using a within-participants sham-controlled crossover design, we will compare the active and sham rTMS conditions on pre- to posttest changes in the RRV of food (primary objective) and the neural modulation of reward, measured via electroencephalography (EEG; secondary objective). We hypothesize that participants will show larger decreases in food reinforcement and increases in brain reward processing after active versus sham rTMS.

METHODS

Participants (n=10) will attend 2 study sessions separated by a washout period. They will be randomized to active rTMS on 1 day and sham rTMS on the other day using a counterbalanced schedule. For both sessions, participants will arrive fasted in the morning and consume a standardized breakfast before being assessed on the RRV of food and reward tasks via EEG before and after rTMS of the left dorsolateral prefrontal cortex.

RESULTS

Recruitment and data collection began in December 2022. As of October 2023, overall, 52 patients have been screened; 36 (69%) screened eligible, and 17 (47%) were enrolled. Of these 17 patients, 3 (18%) were excluded before rTMS, 5 (29%) withdrew, 4 (24%) are in the process of completing the protocol, and 5 (29%) completed the protocol.

CONCLUSIONS

The RESTRAIN study is the first to test whether rTMS can target neural reward circuits to reduce behavioral (RRV) and neural (EEG) measures of food reward in patients who are pursuing MBS. If successful, the results would provide a rationale for a fully powered trial to examine whether rTMS-related changes in food reinforcement translate into healthier eating patterns and improved MBS outcomes. If the results do not support our hypotheses, we will continue this line of research to evaluate whether additional rTMS sessions and pulses as well as different stimulation locations produce clinically meaningful changes in food reinforcement.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05522803; https://clinicaltrials.gov/study/NCT05522803.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/50714.

THE RELATIVE REINFORCING VALUE OF SNACK FOOD IS A SIGNIFICANT PREDICTOR OF FAT LOSS IN WOMEN WITH OVERWEIGHT OR OBESITY

Reinforcing Relative Value (RRV) of food and impulsivity are associated with energy intake and obesity. The study investigated the degree to which changes in RRV and impulsivity independently or interactively predict change in body weight and composition in women with overweight or obesity engaged in either a fast or in a slow weight loss programs. Body weight, body composition, Impulsivity (Barratt Impulsiveness Scale), RRV snack (computerized Behavioural Choice Task) were measured at baseline and post-intervention in 30 women with obesity undergoing either slow (n= 14 -500 kcal/day, 20 weeks) or fast n=16 (-1000kcal/day, 10 weeks) weight reduction. No group*time effects were noted on body composition, impulsivity or RRV, so participants from both groups were pooled for analysis. Multiple regression analyses indicated that none of the impulsivity variables predicted weight- or fat mass (FM) loss. However, Δ RRV snack predicted ΔFM (r=0.40, P=0.046), whereby greater increases in RRV snack were associated with less FM loss. Results indicate that different rates of weight loss do not differentially affect RRV snack or impulsivity traits. However, changes in RRV snack predicted FM loss, suggesting that dietary interventions that either mitigate increases or foster reductions in the RRV snack may yield greater reductions in adiposity. Trial Registration clinicaltrials.gov identifier: NCT04866875 NOVELTY POINTS • No differences in RRV of food were noted between fast and slow weight loss • Weight loss from combined fast and slow groups led to a moderate-sized reduction in the total impulsivity • Greater diet-induced increases in RRV snack was associated with less body fat-loss.

Systematically testing the effects of promotion techniques on children's fruit and vegetables intake on the long term: a protocol study of a multicenter randomized controlled trial

Background

Eating a diet rich in fruit and vegetables is essential for healthy development, protects against chronicle diseases, and increases mental well-being. Numerous studies have consistently shown that children do not consume enough fruit and vegetables, especially among children from low socioeconomic status, while foods high in fat, sugar and salt are over-consumed. In order to improve children’s eating behavior, there is an urgent need to systematically test novel and effective methods to make fruit and vegetables more appealing and increase the intake among children. Therefore, the main aim of the proposed project is to test if food promotion techniques increase children’s fruit and vegetable intake, both on the short- and long-term.

Methods

Three studies will be conducted. First, to develop the vlogs in co-creation, multiple focus groups will be held with (1) children (N = 25, between 8 and 13 years), (2) parents (N = 10), (3) vloggers (N = 5), and (4) fruit and vegetable producers and marketers (N = 5). Second, a multicenter randomized clinical trial will be conducted among 10 primary schools. A mixed repeated measure design with three different conditions will be used: (1) control, (2) a vlog unboxing fruit and vegetables (preparing and tasting), and (3) a vlog doing a challenge with the fruit and vegetables (e.g., contests, tricks, games). Children between 7 and 13 will participate in the experiments (N = 350). Third, after 6 and 12 months follow-up measurements will take place.

Discussion

HFSS foods have higher intrinsically rewarding properties that make them more “wanted” and “liked” than fruit and vegetables, thereby inducing unhealthy eating behavior among children. Additionally, promotion for HFSS foods is omnipresent and increases the rewarding value of these foods. Moreover, some studies showed that the promotion of fruit and vegetables affects the intake, although a recent systematic review shows that evidence is inconclusive and a theoretical understanding for the underlying mechanism is missing. The current study aims to improve the existing knowledge by experimentally testing a newly developed theoretical model.

Trial registration

Netherlands Trial registration:NL8077, received on 12 October 2019.

Feasibility and impact study of a reward-based mobile application to improve adolescents' snacking habits

OBJECTIVE

Adolescents' snacking habits are driven by both explicit reflective and implicit hedonic processes. Hedonic pathways and differences in sensitivity to food rewards in addition to reflective determinants should be considered. The present study evaluated the feasibility and impact of a mobile phone-delivered intervention, incorporating explicit reflective and implicit rewarding strategies, on adolescents' snack intake.

DESIGN

Adolescents (n 988; mean age 14·9 (sd 0·70) years, 59·4 % boys) completed a non-randomized clustered controlled trial. Adolescents (n 416) in the intervention schools (n 3) were provided with the intervention application for four weeks, while adolescents (n 572) in the control schools (n 3) followed the regular curriculum. Outcomes were differences in healthy snacking ratio and key determinants (awareness, intention, attitude, self-efficacy, habits and knowledge). Process evaluation data were collected via questionnaires and through log data of the app.

RESULTS

No significant positive intervention effects on the healthy snack ratio (b=-3·52 (se 1·82), P>0·05) or targeted determinants were observed. Only 268 adolescents started using the app, of whom only fifty-five (20·5 %) still logged in after four weeks. Within the group of users, higher exposure to the app was not significantly associated with positive intervention effects. App satisfaction ratings were low in both high and low user groups. Moderation analyses revealed small positive intervention effects on the healthy snack ratio in high compared with low reward-sensitive boys (b=1·38 (se 0·59), P<0·05).

CONCLUSIONS

The intervention was not able to improve adolescents' snack choices, due to low reach and exposure. Future interventions should consider multicomponent interventions, teacher engagement, exhaustive participatory app content development and tailoring.

Adding a reward increases the reinforcing value of fruit

Adolescents' snack choices could be altered by increasing the reinforcing value (RV) of healthy snacks compared with unhealthy snacks. This study assessed whether the RV of fruit increased by linking it to a reward and if this increased RV was comparable with the RV of unhealthy snacks alone. Moderation effects of sex, hunger, BMI z-scores and sensitivity to reward were also explored. The RV of snacks was assessed in a sample of 165 adolescents (15·1 (sd 1·5) years, 39·4 % boys and 17·4 % overweight) using a computerised food reinforcement task. Adolescents obtained points for snacks through mouse clicks (responses) following progressive ratio schedules of increasing response requirements. Participants were (computer) randomised to three experimental groups (1:1:1): fruit (n 53), fruit+reward (n 60) or unhealthy snacks (n 69). The RV was evaluated as total number of responses and breakpoint (schedule of terminating food reinforcement task). Multilevel regression analyses (total number of responses) and Cox's proportional hazard regression models (breakpoint) were used. The total number of responses made were not different between fruit+reward and fruit (b -473; 95 % CI -1152, 205, P=0·17) or unhealthy snacks (b410; 95 % CI -222, 1043, P=0·20). The breakpoint was slightly higher for fruit than fruit+reward (HR 1·34; 95 % CI 1·00, 1·79, P=0·050), whereas no difference between unhealthy snacks and fruit+reward (HR 0·86; 95 % CI 0·62, 1·18, P=0·34) was observed. No indication of moderation was found. Offering rewards slightly increases the RV of fruit and may be a promising strategy to increase healthy food choices. Future studies should however, explore if other rewards, could reach larger effect sizes.

Cookie or fruit? Relative reinforcing value of snack foods among preschoolers with overweight/obesity compared to healthy weight

The reinforcing value of food is an important determinant of food intake. Research has yet to examine the relative reinforcing value (RRV) of snack foods in young children with overweight and obesity (OW/OB). The current study compared the RRV of high-energy dense foods (cookies) to low-energy dense foods (fruits) between preschoolers with OW/OB and healthy weight (HW). RRV of cookies and fruits in preschoolers with OW/OB (n = 30; M_age = 4.4 ± 0.84; 60% male) and HW (n = 30; M_age = 4.5 ± 0.85; 70% male) was assessed with a developmentally-tailored computer program which used a progressive fixed ratio reward schedule. The results showed that the RRV of cookies was significantly higher for preschoolers with OW/OB compared to HW while the RRV of fruits was significantly higher for preschoolers with HW compared to OW/OB. These results suggest that cookies are more reinforcing for preschoolers with OW/OB and less reinforcing for preschoolers with HW. Finding ways to reduce the reinforcing value of high-energy dense snack foods and identify alternatives that are as reinforcing for preschoolers is a challenge for weight control treatments.

Association of the dopamine D2 receptor rs1800497 polymorphism and eating behavior in Chilean children

OBJECTIVES

Studies have established a strong genetic component in eating behavior. The TaqI A1 polymorphism (rs1800497) has previously been associated with obesity and eating behavior. Additionally, this polymorphism has been associated with diminished dopamine D2 receptor (DRD2) density, higher body mass, and food reinforcement. The aim of this study was to evaluate the association between the DRD2 rs1800497 polymorphism and eating behavior in Chilean children.

METHODS

This was a cross-sectional study in which we selected 258 children (44% girls, 56% boys; ages 8-14 y) with a wide variation in body mass index. Anthropometric measurements were performed by standard procedures. Eating behavior was assessed using the Eating in Absence of Hunger Questionnaire (EAHQ), Child Eating Behavior Questionnaire, and the Food Reinforcement Value Questionnaire. Genotype of the rs1800497 was determined by polymerase chain reaction-restriction fragment length polymorphism. Association of the TaqI A1 variant (T allele) with eating behavior was assessed using nonparametric tests.

RESULTS

Compared with normal-weight children, the obese group demonstrated higher scores on the External Eating and Fatigue/Boredom subscales of the EAHQ. Higher scores were assessed in Food Responsiveness, Emotional Overeating, Enjoyment to Food and Desire to Drink subscales (P < 0.001) and lower scores of the Satiety Responsiveness and Slowness in Eating (P < 0.05). In the sex-specific analysis, the TaqI A1 allele was associated with higher scores on Satiety Responsiveness and Emotional Undereating subscales in obese girls, and higher scores of Enjoyment of Food subscale in boys.

CONCLUSION

The TaqI A1 polymorphism may be a risk factor for eating behavior traits that may predispose children to greater energy intake and obesity.

To work or not to work: Neural representation of cost and benefit of instrumental action

By definition, instrumental actions are performed in order to obtain certain goals. Nevertheless, the attainment of goals typically implies obstacles, and response vigor is known to reflect an integration of subjective benefit and cost. Whereas several brain regions have been associated with cost/benefit ratio decision-making, trial-by-trial fluctuations in motivation are not well understood. We review recent evidence supporting the motivational implications of signal fluctuations in the mesocorticolimbic system. As an extension of "set-point" theories of instrumental action, we propose that response vigor is determined by a rapid integration of brain signals that reflect value and cost on a trial-by-trial basis giving rise to an online estimate of utility. Critically, we posit that fluctuations in key nodes of the network can predict deviations in response vigor and that variability in instrumental behavior can be accounted for by models devised from optimal control theory, which incorporate the effortful control of noise. Notwithstanding, the post hoc analysis of signaling dynamics has caveats that can effectively be addressed in future research with the help of two novel fMRI imaging techniques. First, adaptive fMRI paradigms can be used to establish a time-order relationship, which is a prerequisite for causality, by using observed signal fluctuations as triggers for stimulus presentation. Second, real-time fMRI neurofeedback can be employed to induce predefined brain states that may facilitate benefit or cost aspects of instrumental actions. Ultimately, understanding temporal dynamics in brain networks subserving response vigor holds the promise for targeted interventions that could help to readjust the motivational balance of behavior.

Is it Worth the Effort? Novel Insights into Obesity-Associated Alterations in Cost-Benefit Decision-Making

Cost-benefit decision-making entails the process of evaluating potential actions according to the trade-off between the expected reward (benefit) and the anticipated effort (costs). Recent research revealed that dopaminergic transmission within the fronto-striatal circuitry strongly modulates cost-benefit decision-making. Alterations within the dopaminergic fronto-striatal system have been associated with obesity, but little is known about cost-benefit decision-making differences in obese compared with lean individuals. With a newly developed experimental task we investigate obesity-associated alterations in cost-benefit decision-making, utilizing physical effort by handgrip-force exertion and both food and non-food rewards. We relate our behavioral findings to alterations in local gray matter volume assessed by structural MRI. Obese compared with lean subjects were less willing to engage in physical effort in particular for high-caloric sweet snack food. Further, self-reported body dissatisfaction negatively correlated with the willingness to invest effort for sweet snacks in obese men. On a structural level, obesity was associated with reductions in gray matter volume in bilateral prefrontal cortex. Nucleus accumbens volume positively correlated with task induced implicit food craving. Our results challenge the common notion that obese individuals are willing to work harder to obtain high-caloric food and emphasize the need for further exploration of the underlying neural mechanisms regarding cost-benefit decision-making differences in obesity.

Food packaging cues influence taste perception and increase effort provision for a recommended snack product in children

Food marketing research shows that child-directed marketing cues have pronounced effects on food preferences and consumption, but are most often placed on products with low nutritional quality. Effects of child-directed marketing strategies for healthy food products remain to be studied in more detail. Previous research suggests that effort provision explains additional variance in food choice. This study investigated the effects of packaging cues on explicit preferences and effort provision for healthy food items in elementary school children. Each of 179 children rated three, objectively identical, recommended yogurt-cereal-fruit snacks presented with different packaging cues. Packaging cues included a plain label, a label focusing on health aspects of the product, and a label that additionally included unknown cartoon characters. The children were asked to state the subjective taste-pleasantness of the respective food items. We also used a novel approach to measure effort provision for food items in children, namely handgrip strength. Results show that packaging cues significantly induce a taste-placebo effect in 88% of the children, i.e., differences in taste ratings for objectively identical products. Taste ratings were highest for the child-directed product that included cartoon characters. Also, applied effort to receive the child-directed product was significantly higher. Our results confirm the positive effect of child-directed marketing strategies also for healthy snack food products. Using handgrip strength as a measure to determine the amount of effort children are willing to provide for a product may explain additional variance in food choice and might prove to be a promising additional research tool for field studies and the assessment of public policy interventions.

Demographic and psychographic associations of consumer intentions to purchase healthier food products

OBJECTIVE

This study investigated the associations of nutrition concerns, demographics, universalism (community oriented) values, perceived control over personal health and food buying, and perceived influence over the food system with intentions to purchase low fat, sugar and salt (LFSS) food products.

METHODS

A national online survey of 2204 Australian consumers administered in November 2011. Structural equation modeling was used to examine associations of LFSS purchasing intentions with demographic, values, perceived control, and influence factors.

RESULTS

Nutrition concern, perceived influence over the food system, and universalism values were key predictors of LFSS purchasing intentions. Almost two thirds (64.6%) of the variance associated with LFSS purchasing was explained by the structural equation model.

CONCLUSION

Communication programs which focus on universalism values, nutrition concern and perceived influence over the food system are likely to increase LFSS purchasing and perhaps reduce the demand for energy dense, nutrient poor foods.