Food cue reactivity and craving predict eating and weight gain: a meta-analytic review

Food Cues and Obesity: Overpowering Hormones and Energy Balance Regulation

PURPOSE OF REVIEW

In the modern obesogenic environment, food cues play a crucial role in the development of obesity by disrupting hormone and energy balance mechanisms. Thus, it is critical to understand the neurobiology of feeding behaviors and obesity in the context of ubiquitous food cues. The current paper reviews the physiology of feeding, hormonal regulation of energy balance, and food cue responses and discusses their contributions to obesity.

RECENT FINDINGS

Food cues have strong impact on human physiology. Obese individuals have altered food cue-elicited responses in the brain and periphery, overpowering hormone and energy balance regulation. Disrupted homeostasis during food cue exposure leads to continued food intake, unsuccessful weight management, and poor treatment outcomes, which further contributes to obesity epidemic. Findings from the review emphasize the crucial role of food cues in obesity epidemic, which necessitates multidimensional approaches to the prevention and treatment of obesity, including psychosocial interventions to reduce food cue reactivity, along with conventional treatment.

Lower dopamine tone in the striatum is associated with higher body mass index

Existing literature suggests that striatal dopamine (DA) tone may be altered in individuals with higher body mass index (BMI), but evidence accrued so far only offers an incomplete view of their relationship. Here, we characterized striatal DA tone using more comprehensive measures within a larger sample than previously reported. In addition, we explored if there was a relationship between striatal DA tone and disinhibited eating. 60 healthy participants underwent a 6-[¹⁸F]fluoro-L-3,4-dihydroxyphenylalanine (¹⁸F-DOPA) positron emission tomography (PET) scan. Disinhibited eating was measured with the Three-Factor Eating Questionnaire on a baseline visit. Individual whole-brain PET parameter estimates, namely ¹⁸F-DOPA influx rate constant (k_occ i.e. DA synthesis capacity), ¹⁸F-DA washout rate (k_loss) and effective distribution volume ratio (EDVR= k_occ/ k_loss), were derived with a reversible-tracer graphical analysis approach. We then computed parameter estimates for three regions-of-interests (ROIs), namely the ventral striatum, putamen and caudate. Overweight/mildly obese individuals had lowered EDVR than normal weight individuals in all three ROIs. The most prominent of these associations, driven by lowered k_occ (r = -.28, p = .035) and heightened k_loss (r = .48, p < .001), was found in the ventral striatum (r = -.46, p < .001). Disinhibition was greater in higher-BMI individuals (r = .31, p = .015), but was unrelated to PET measures and did not explain the relationship between PET measures and BMI. In sum, our findings resonate with the notion that overweight/mildly obese individuals have lower striatal DA tone and suggest new avenues for investigating their underlying mechanisms.

Investigating the impact of a health game on implicit attitudes towards food and food choice behaviour of young adults

Improving diets by stimulating fruit and vegetable consumption might be beneficial, in particular when they substitute energy-dense products. The aim of present study was to investigate whether a health game can be used to positively affect healthy implicit attitudes (IAs) towards food and subsequent food choice behaviour of young adults. A 2 (Time: baseline vs. post-test) x 2 (Condition: health game vs. control game) x 2 (Baseline IAs: healthy IAs vs. less healthy IAs) mixed-subjects design was used with 125 participants (age: M = 20.17, SD = 1.88). IAs towards food were assessed at baseline and post-test using an Implicit Association Test (IAT). Additionally, food choice behaviour was assessed after game play. At baseline, the majority of participants had healthy IAs (i.e., favouring fruit over chocolate snacks). At post-test, significantly less healthy IAs were observed in the control condition, while this reduction was not significant in the health game condition. Regarding food choice behaviour, participants with healthy baseline IAs were more likely to select fruit in the health game condition than participants with healthy baseline IAs in the control game condition. However, participants with less healthy baseline IAs were less likely to select fruit in the health game condition than in the control condition. We found tentative support that health games can be used to influence IAs towards food and positively affect food choice behaviour. However, this influence was only observed for those with healthy baseline IAs. The current version of the health game would primarily benefit those already healthy and could negatively affect those that need the intervention most, so modifications are recommendable.

Learned Overeating: Applying Principles of Pavlovian Conditioning to Explain and Treat Overeating

PURPOSE OF REVIEW

This review provides an overview of recent findings relating to the role of Pavlovian conditioning in food cue reactivity, including its application to overeating and weight loss interventions.

RECENT FINDINGS

Both in the laboratory and in real life, cue-elicited appetitive reactivity (e.g., eating desires) can be easily learned, but (long-term) extinction is more difficult. New findings suggest impaired appetitive learning in obesity, which might be causally related to overeating. The clinical analogue of extinction-cue exposure therapy-effectively reduces cue-elicited cravings and overeating. While its working mechanisms are still unclear, some studies suggest that reducing overeating expectancies is important.

SUMMARY

Pavlovian learning theory provides a still undervalued theoretical framework of how cravings and overeating can be learned and how they might be effectively tackled. Future studies should aim to elucidate inter-individual differences in Pavlovian conditioning, study ways to strengthen (long-term) extinction, and investigate the working mechanisms of cue exposure therapy.

Sustained impact of energy-dense TV and online food advertising on children's dietary intake: a within-subject, randomised, crossover, counter-balanced trial

Background

Policies restricting children’s exposure to unhealthy food marketing have been impeded by the lack of evidence showing a direct link between food advertising exposure and children’s energy intake and body weight. Food advertising exposure increases children’s immediate food consumption, but whether this increased intake is compensated for at later eating occasions is not known; consequently the sustained effect on diets remains unclear.

Methods

We conducted a within-subject, randomised, crossover, counterbalanced study across four, six-day holiday camps in New South Wales, Australia between April 2016 and January 2017. Children (7–12 years, n = 160) were recruited via local schools, email networks and social media. Two gender- and age-balanced groups were formed for each camp (n = 20), randomised to either a multiple- or single- media condition and exposed to food and non-food advertising in an online game and/or a television cartoon. Children’s food consumption (kilojoules) was measured at a snack immediately after exposure and then at lunch later in the day. Linear mixed models were conducted to examine relationships between food advertising exposure and dietary intake, taking into account gender, age and weight status.

Results

All children in the multiple-media condition ate more at a snack after exposure to food advertising compared with non-food advertising; this was not compensated for at lunch, leading to additional daily food intake of 194 kJ (95% CI 80–308, p = 0.001, d = 0.2). Exposure to multiple-media food advertising compared with a single-media source increased the effect on snack intake by a difference of 182 kJ (95% CI 46–317, p = 0.009, d = 0.4). Food advertising had an increased effect among children with heavier weight status in both media groups.

Conclusion

Online (‘advergame’) advertising combined with TV advertising exerted a stronger influence on children’s food consumption than TV advertising alone. The lack of compensation at lunch for children’s increased snack intake after food advertising exposure suggests that unhealthy food advertising exposure contributes to a positive energy-gap, which could cumulatively lead to the development of overweight.

Trial registration

Australian New Zealand Clinical Trials Registry, number ACTRN12617001230347 (Retrospectively registered).

The computational form of craving is a selective multiplication of economic value

Craving is a specific desire state that biases choice toward the desired object. Although extremely common, and in its pathological form a major contributor to negative health outcomes as in addiction and obesity, craving is not well understood. In a laboratory model of craving, we find “craving” is reflected in people’s momentary willingness to pay for the things they desire, and for subjectively similar things, consistent with a transient, good-selective change in subjective valuation. We further find the value of the desired goods increases multiplicatively, which might explain several escalation behaviors associated with craving in real-world environments. This opens more lines of research regarding the computational form of craving in health and disease, with implications for marketing actions and consumer choice.

Craving is thought to be a specific desire state that biases choice toward the desired object, be it chocolate or drugs. A vast majority of people report having experienced craving of some kind. In its pathological form craving contributes to health outcomes in addiction and obesity. Yet despite its ubiquity and clinical relevance we still lack a basic neurocomputational understanding of craving. Here, using an instantaneous measure of subjective valuation and selective cue exposure, we identify a behavioral signature of a food craving-like state and advance a computational framework for understanding how this state might transform valuation to bias choice. We find desire induced by exposure to a specific high-calorie, high-fat/sugar snack good is expressed in subjects’ momentary willingness to pay for this good. This effect is selective but not exclusive to the exposed good; rather, we find it generalizes to nonexposed goods in proportion to their subjective attribute similarity to the exposed ones. A second manipulation of reward size (number of snack units available for purchase) further suggested that a multiplicative gain mechanism supports the transformation of valuation during laboratory craving. These findings help explain how real-world food craving can result in behaviors inconsistent with preferences expressed in the absence of craving and open a path for the computational modeling of craving-like phenomena using a simple and repeatable experimental tool for assessing subjective states in economic terms.

Neurofeedback of visual food cue reactivity: a potential avenue to alter incentive sensitization and craving

FMRI-based neurofeedback transforms functional brain activation in real-time into sensory stimuli that participants can use to self-regulate brain responses, which can aid the modification of mental states and behavior. Emerging evidence supports the clinical utility of neurofeedback-guided up-regulation of hypoactive networks. In contrast, down-regulation of hyperactive neural circuits appears more difficult to achieve. There are conditions though, in which down-regulation would be clinically useful, including dysfunctional motivational states elicited by salient reward cues, such as food or drug craving. In this proof-of-concept study, 10 healthy females (mean age = 21.40 years, mean BMI = 23.53) who had fasted for 4 h underwent a novel 'motivational neurofeedback' training in which they learned to down-regulate brain activation during exposure to appetitive food pictures. FMRI feedback was given from individually determined target areas and through decreases/increases in food picture size, thus providing salient motivational consequences in terms of cue approach/avoidance. Our preliminary findings suggest that motivational neurofeedback is associated with functionally specific activation decreases in diverse cortical/subcortical regions, including key motivational areas. There was also preliminary evidence for a reduction of hunger after neurofeedback and an association between down-regulation success and the degree of hunger reduction. Decreasing neural cue responses by motivational neurofeedback may provide a useful extension of existing behavioral methods that aim to modulate cue reactivity. Our pilot findings indicate that reduction of neural cue reactivity is not achieved by top-down regulation but arises in a bottom-up manner, possibly through implicit operant shaping of target area activity.

Cue exposure therapy reduces overeating of exposed and non-exposed foods in obese adolescents

BACKGROUND AND OBJECTIVES

This study tested whether two sessions of food cue exposure therapy reduced eating in the absence of hunger (EAH), specified for exposed and non-exposed food, in overweight and obese adolescents, and whether habituation of food cue reactivity and reduced CS-US expectancies predicted a decrease in EAH.

METHODS

41 overweight adolescents (aged 12-18 years) were randomly assigned to a cue exposure intervention or a lifestyle intervention (control condition). Habituation of food cue reactivity (self-reported desire to eat and salivation) and CS-US expectancy were measured during both sessions, and EAH was measured at the end of session two.

RESULTS

Compared to the control condition, the cue exposure condition showed less EAH for the exposed food item as well as for the non-exposed food items. Larger within-session (WSH) and between-session habituation (BSH) of cue reactivity were not related to less EAH, change in CS-US expectancy was unrelated to EAH.

LIMITATIONS

The study was underpowered, and compliance to homework instructions between sessions was poor, intervention effects might have been larger when participants adhered to daily homework exercises.

CONCLUSIONS

Food cue exposure was effective to reduce EAH of exposed and non-exposed food items, indicating generalisability of the exposure effect. In line with exposure effects in anxiety disorders, habituation was not found to benefit outcome, though the present data do also not provide evidence that CS-US expectancy violation predicts EAH.

Trace Amine Associated Receptor 1 (TAAR1) Modulation of Food Reward

Eating disorders and some forms of obesity are characterized by addictive-like, compulsive eating behavior which contains numerous similarities with compulsive drug use. Food intake is in part mediated by reward and reinforcement processes that can become dysregulated in these disorders. Additionally, impairments in inhibitory control regulation of reward-related responding can cause or further exacerbate binge and compulsive eating. Dysfunctions in two neurotransmitter systems in the mesocorticolimbic pathway, dopamine and glutamate, are thought to contribute to maladaptive eating behaviors. The trace amine associated receptor 1 (TAAR1) system is a promising therapeutic target for compulsive eating behavior due to the role of TAAR1 in synaptic transmission and in the modulation of dopaminergic and glutamatergic signaling. In support of this notion, the TAAR1 agonist RO5256390 was found to decrease the reinforcing effects of palatable food-cues and to reduce binge-like and compulsive-like eating of palatable food. Additionally, prolonged, intermittent access to palatable food was shown to downregulate TAAR1 in the prefrontal cortex, suggesting a potential role for TAAR1 signaling in inhibitory control processes. Research into the role of TAAR1 in addiction, including TAAR1’s ability to modulate psychostimulant reward and reinforcement, bolsters support for TAAR1 agonism as a pharmacological treatment for compulsive eating and other addictive behaviors. This review summarizes the evidence for TAAR1 agonism as a promising therapeutic for compulsive eating behavior as well as the hypothesized mechanism responsible for these effects.

Contributions of Pavlovian incentive motivation to cue-potentiated feeding

Cues signaling the availability of palatable food acquire the ability to potentiate food seeking and consumption. The current study employed a combination of behavioral, pharmacological, and analytical techniques to probe the role of Pavlovian incentive motivation in cue-potentiated feeding. We show that a cue paired with sucrose solution (CS+) can transfer its control over feeding to stimulate sucrose consumption at a new receptacle, and that this effect depends on activation of D1 dopamine receptors, which is known to modulate other forms of cue-motivated behavior but not taste palatability. Microstructural analyses of sucrose-licking behavior revealed that the CS+ tended to increase the frequency with which rats engaged in active bouts of licking behavior without having a reliable effect on the duration of those licking bouts, a measure that was instead associated with sucrose palatability. Furthermore, we found that individual differences in CS+ elicited increases in bout frequency were associated with total sucrose intake at test, supporting the view that this process was related to meaningful dysregulation of eating behavior. The current study, therefore, (1) demonstrates that a dopamine-dependent Pavlovian incentive motivational process can mediate cue-potentiated feeding, and (2) lays out an experimental and analytical approach for parsing this aspect of behavior.

Ventromedial prefrontal cortex mediates sex differences in persistent cognitive drive for food

Contemporary environments are saturated with food cues that stimulate appetites in the absence of hunger, which leads to maladaptive eating. These settings can induce persistent drive to eat, as learned behaviors can reappear after extinction. Behavioral paradigms of responding renewal provide a valuable framework to study how food cues contribute to the inability to resist palatable foods and change maladaptive eating habits. Using a rat model for this persistent food motivation, we determined sex differences in the causal function for the ventromedial prefrontal cortex (vmPFC) during context-mediated renewal of responding to food cues. Previously, we found behavioral sex differences (only males exhibited renewal) and differential recruitment within the vmPFC (increased Fos induction in males but decreased in females). Here, we used DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) to silence vmPFC neurons in males and to stimulate vmPFC neurons in females specifically during renewal. Silencing vmPFC neurons in males disrupted renewal of responding to a food cue, while stimulating vmPFC neurons in females induced this behavior. These findings demonstrate sex differences in the vmPFC function in a model of food seeking relevant to environmentally driven appetites contributing to obesity and eating disorders.

Appetitive drives for ultra-processed food products and the ability of text warnings to counteract consumption predispositions

OBJECTIVE

The present study aimed to (i) assess the appetitive drives evoked by the visual cues of ultra-processed food and drink products and (ii) investigate whether text warnings reduce appetitive drives and consumers' reported intentions to eat or drink ultra-processed products.

DESIGN

In Study I, a well-established psychometric tool was applied to estimate the appetitive drives associated with ultra-processed products using sixty-four image representations. Sixteen product types with four exemplars of a given product were included. Pictures from the International Affective Picture System (IAPS) served as controls. The two exemplars of each product type rated as more appetitive were selected for investigation in the second study. Study II assessed the impact of textual warnings on the appetitive drive towards these thirty-two exemplars. Each participant was exposed to two picture exemplars of the same product type preceded by a text warning or a control text. After viewing each displayed picture, the participants reported their emotional reactions and their intention to consume the product.

SETTING

Controlled classroom experiments SUBJECTS: Undergraduate students (Study I: n 215, 135 women; Study II: n 98, 52 women).

RESULTS

In Study I, the pictures of ultra-processed products prompted an appetitive motivation associated with the products' nutritional content. In Study II, text warnings were effective in reducing the intention to consume and the appetitive drive evoked by ultra-processed products.

CONCLUSIONS

This research provides initial evidence favouring the use of text warnings as a public policy tool to curb the powerful influence of highly appetitive ultra-processed food cues.

Children's food and satiety responsiveness in association with post-prandial glucose following a standardized liquid meal

Children's responsiveness to food cues and satiety may put them at greater risk for obesity; however, little is known about the physiological mechanisms underlying children's responsiveness to food and satiety. The objective of this study was to examine the association between children's post-prandial glucose responses and maternal report of their eating behaviours. A secondary data analysis was conducted using partial correlation analyses adjusted for gender in a sample of children aged 5-10 years and their mothers (N = 28 dyads). Standardized liquid meal tests were administered to children and blood samples were obtained over the following 4 h. Mothers completed the Children's Eating Behaviour Questionnaire. An earlier post-prandial peak glucose concentration was associated with greater food responsiveness (r = -0.39, P = 0.04) but not satiety responsiveness. The percent increase in glucose from fasting to peak also tended to be inversely associated with greater food responsiveness (r = -0.38, P = 0.05). Results suggest that earlier and smaller post-prandial glucose excursions may be related to children's response to food cues. Future research should use objective methods to examine whether the association of post-prandial glucose with food responsiveness prospectively contributes to weight gain.

Effect of Lorcaserin Alone and in Combination with Phentermine on Food Cravings After 12-Week Treatment: A Randomized Substudy

OBJECTIVE

This study evaluated the effect of lorcaserin 10 mg twice daily (LOR BID), or with phentermine 15 mg once daily (LOR BID + PHEN QD) and 15 mg twice daily (LOR BID + PHEN BID), in conjunction with energy restriction on food cravings.

METHODS

Two hundred and thirty-five patients without diabetes but with obesity or overweight and ≥ 1 comorbidity received LOR BID, LOR BID + PHEN QD, or LOR BID + PHEN BID for 12 weeks in a randomized double-blind study. The Food Craving Inventory (FCI) and the Control of Eating Questionnaire (COEQ) were administered over 12 weeks.

RESULTS

The FCI total score and the subscale scores reduced from baseline in all groups. The least squares means (95% confidence intervals) for the total scores were -0.65 (-0.75 to -0.55), -0.75 (-0.84 to -0.65), and -0.84 (-0.95 to -0.74) in the LOR BID, LOR BID + PHEN QD, and LOR BID + PHEN BID groups, respectively. Cravings assessed by COEQ reduced from baseline in all groups. In general, the combination treatments were more effective than lorcaserin alone. At week 12, except for fruit juice and dairy products, general and specific cravings reduced in LOR BID + PHEN BID compared with LOR BID (P < 0.05).

CONCLUSIONS

Lorcaserin in combination with phentermine improves control of food cravings during short-term energy restriction.

Preliminary evidence for genetic overlap between body mass index and striatal reward response

The reward-processing network is implicated in the aetiology of obesity. Several lines of evidence suggest obesity-linked genetic risk loci (such as DRD2 and FTO) may influence individual variation in body mass index (BMI) through neuropsychological processes reflected in alterations in activation of the striatum during reward processing. However, no study has tested the broader hypotheses that (a) the relationship between BMI and reward-related brain activation (measured through the blood oxygenation-dependent (BOLD) signal) may be observed in a large population study and (b) the overall genetic architecture of these phenotypes overlap, an assumption critical for the progression of imaging genetic studies in obesity research. Using data from the Human Connectome Project (N = 1055 healthy, young individuals: average BMI = 26.4), we first establish a phenotypic relationship between BMI and ventral striatal (VS) BOLD during the processing of rewarding (monetary) stimuli (β = 0.44, P = 0.013), accounting for potential confounds. BMI and VS BOLD were both significantly influenced by additive genetic factors (H2r = 0.57; 0.12, respectively). Further decomposition of this variance suggested that the relationship was driven by shared genetic (ρ g = 0.47, P = 0.011), but not environmental (ρ E = -0.07, P = 0.29) factors. To validate the assumption of genetic pleiotropy between BMI and VS BOLD, we further show that polygenic risk for higher BMI is also associated with increased VS BOLD response to appetitive stimuli (calorically high food images), in an independent sample (N = 81; P FWE-ROI < 0.005). Together, these observations suggest that the genetic factors link risk to obesity to alterations within key nodes of the brain's reward circuity. These observations provide a basis for future work exploring the mechanistic role of genetic loci that confer risk for obesity using the imaging genetics approach.

Triethylene glycol-like effects of Ashwagandha (Withania somnifera (L.) Dunal) root extract devoid of withanolides in stressed mice

Background

The objective of the study is to compare stress resistance-promoting effect of triethylene glycol (TEG) and root extract of Ashwagandha (Withania somnifera) i.e. withanolide-free root extract of Withania somnifera (WFWS).

Materials and Methods

Mice groups treated orally with 10 mg/kg TEG or WFWS (3.3, 10, 33.3, or 100 mg/kg) for 12 consecutive days were subjected to foot shock stress-triggered hyperthermia test on the 1^st, 5^th, 7^th and 10^th day and to marble-burying test on the following 2 days. Effects of treatment on stress-triggered alteration in body weight, core temperature, blood glucose, insulin and cortisol level were quantified and statistically analyzed.

Results

WFWS doses up to 10 mg/kg/day were as effective as TEG in affording protection against stress-triggered alteration in body weight, core temperature and marble-burying behavior. Protection against stress-triggered alteration in blood glucose and insulin level, as well as antidepressants or anxiolytic-like activities in the behavioral test, were observed in the higher two WFWS doses (33.3 and 100 mg/kg) treated groups only.

Conclusion

Ashwagandha metabolites other than withanolides contribute to its stress resistance increasing effects. The observations suggest that modulation of physiological functions of gut microbiota may be involved in the mode of action of Withania somnifera root extracts.

The real deal: Willingness-to-pay and satiety expectations are greater for real foods versus their images

Laboratory studies of human dietary choice have relied on computerized two-dimensional (2D) images as stimuli, whereas in everyday life, consumers make decisions in the context of real foods that have actual caloric content and afford grasping and consumption. Surprisingly, few studies have compared whether real foods are valued more than 2D images of foods, and in the studies that have, differences in the stimuli and testing conditions could have resulted in inflated bids for the real foods. Moreover, although the caloric content of food images has been shown to influence valuation, no studies to date have investigated whether 'real food exposure effects' on valuation reflect greater sensitivity to the caloric content of real foods versus images. Here, we compared willingness-to-pay (WTP) for, and expectations about satiety after consuming, everyday snack foods that were displayed as real foods versus 2D images. Critically, our 2D images were matched closely to the real foods for size, background, illumination, and apparent distance, and trial presentation and stimulus timing were identical across conditions. We used linear mixed effects modeling to determine whether effects of display format were modulated by food preference and the caloric content of the foods. Compared to food images, observers were willing to pay 6.62% more for (Experiment 1) and believed that they would feel more satiated after consuming (Experiment 2), foods displayed as real objects. Moreover, these effects appeared to be consistent across food preference, caloric content, as well as observers' estimates of the caloric content of the foods. Together, our results confirm that consumers' perception and valuation of everyday foods is influenced by the format in which they are displayed. Our findings raise important new insights into the factors that shape dietary choice in real-world contexts and highlight potential avenues for improving public health approaches to diet and obesity.

The Effects of Experimental Manipulation of Sleep Duration on Neural Response to Food Cues

Despite growing literature on neural food cue responsivity in obesity, little is known about how the brain processes food cues following partial sleep deprivation and whether short sleep leads to changes similar to those observed in obesity. We used functional magnetic resonance imaging (fMRI) to test the hypothesis that short sleep leads to increased reward-related and decreased inhibitory control-related processing of food cues.In a within-subject design, 30 participants (22 female, mean age = 36.7 standard deviation = 10.8 years, body mass index range 20.4-40.7) completed four nights of 6 hours/night time-in-bed (TIB; short sleep) and four nights of 9 hours/night TIB (long sleep) in random counterbalanced order in their home environments. Following each sleep condition, participants completed an fMRI scan while viewing food and nonfood images.A priori region of interest analyses revealed increased activity to food in short versus long sleep in regions of reward processing (eg, nucleus accumbens/putamen) and sensory/motor signaling (ie, right paracentral lobule, an effect that was most pronounced in obese individuals). Contrary to the hypothesis, whole brain analyses indicated greater food cue responsivity during short sleep in an inhibitory control region (right inferior frontal gyrus) and ventral medial prefrontal cortex, which has been implicated in reward coding and decision-making (false discovery rate corrected q = 0.05).These findings suggest that sleep restriction leads to both greater reward and control processing in response to food cues. Future research is needed to understand the dynamic functional connectivity between these regions during short sleep and whether the interplay between these neural processes determines if one succumbs to food temptation.

Altered appetitive conditioning in overweight and obese women

Overweight and obese individuals show increased psychological and physiological reactivity to food cues and many of them have difficulties in achieving long-term weight loss. The current study tests whether abnormalities in the learning and extinction of appetitive responses to food cues might be responsible for this. Overweight/obese and healthy weight women completed a differential appetitive conditioning task using food as rewards, while eating expectancies, eating desires, conditioned stimulus evaluations, salivation, and electrodermal responses were assessed during an acquisition and extinction phase. Results suggested reduced discriminative conditioning in the overweight/obese group, as reflected by a worse acquisition of differential eating desires and no successful acquisition of differential evaluative responses. Some evidence was also found for impaired contingency learning in overweight and obese individuals. No group differences in conditioned salivation and skin conductance responses were found and no compelling evidence for differences in extinction was found as well. In sum, the current findings indicate that overweight and obesity may be characterized by reduced appetitive conditioning. It is suggested that this could be causally related to overeating via stronger context conditioning or a tendency towards overgeneralization in overweight and obese individuals.

Processing of visual food cues during bitter taste perception in female patients with binge-eating symptoms: A cross-modal ERP study

OBJECTIVE

In healthy individuals, the perception of an intense bitter taste decreased the reward value of visual food cues, as reflected by the reduction of a specific event-related brain potential (ERP), frontal late positivity. The current cross-modal ERP study investigated responses of female patients with binge-eating symptoms (BES) to this type of visual-gustatory stimulation.

METHODS

Women with BES (n=36) and female control participants (n=38) viewed food images after they rinsed their mouth with either bitter wormwood tea or water.

RESULTS

Relative to controls, the patients showed elevated late positivity (LPP: 400-700ms) to the food images in the bitter condition. The LPP source was located in the medial prefrontal cortex. Both groups did not differ in the ratings for the fluids (intensity, bitterness, disgust).

CONCLUSIONS

This ERP study showed that a bitter taste did not decrease late positivity to visual food cues (reflecting food reward) in women with BES.

SIGNIFICANCE

The atypical bitter responding might be a biological marker of this condition and possibly contributes to overeating. Future studies should additionally record food intake behavior to further investigate this mechanism.

Dapagliflozin once daily plus exenatide once weekly in obese adults without diabetes: Sustained reductions in body weight, glycaemia and blood pressure over 1 year

AIMS

Dapagliflozin and exenatide reduce body weight by differing mechanisms. Dual therapy with these agents reduces body weight, adipose tissue volume, glycaemia and systolic blood pressure (SBP) over 24 weeks. Here, we examined these effects over 1 year in obese adults without diabetes.

MATERIALS AND METHODS

Obese adults without diabetes (N = 50; aged 18-70 years; body mass index, 30-45 kg/m² ) were initially randomized to double-blind oral dapagliflozin 10 mg once daily plus subcutaneous long-acting exenatide 2 mg once weekly or to placebo. They entered an open-label extension from 24 to 52 weeks during which all participants received active treatment.

RESULTS

Of the original 25 dapagliflozin + exenatide-treated and 25 placebo-treated participants, respectively, 21 (84%) and 17 (68%) entered the open-label period and 16 (64%) and 17 (68%) completed 52 weeks of treatment. At baseline, mean body weight was 104.6 kg, and 73.5% of participants had prediabetes (impaired fasting glucose or impaired glucose tolerance). Reductions with dapagliflozin + exenatide at 24 weeks were sustained at 52 weeks, respectively, for body weight (-4.5 and -5.7 kg), total adipose tissue volume (-3.8 and -5.3 L), proportion with prediabetes (34.8% and 35.3%), and SBP (-9.8 and -12.0 mm Hg). Effects on body weight, SBP and glycaemia at 52 weeks with placebo → dapagliflozin + exenatide were similar to those observed with continuation of dapagliflozin + exenatide. Nausea and injection-site reactions were more frequent with dapagliflozin + exenatide than with placebo and diminished over time. Safety and tolerability were similar to that in previous diabetes trials with these agents. No clear difference in adverse event-related withdrawals between placebo and active treatment periods was observed.

CONCLUSIONS

Dapagliflozin + exenatide dual therapy produced sustained reductions in body weight, prediabetes and SBP over 52 weeks and was well tolerated in obese adults without diabetes.

A Randomised Controlled Comparison of Second-Level Treatment Approaches for Treatment-Resistant Adults with Bulimia Nervosa and Binge Eating Disorder: Assessing the Benefits of Virtual Reality Cue Exposure Therapy

A question that arises from the literature on therapy is whether second-level treatment is effective for patients with recurrent binge eating who fail first-level treatment. It has been shown that subjects who do not stop binge eating after an initial structured cognitive-behavioural treatment (CBT) programme benefit from additional CBT (A-CBT) sessions; however, it has been suggested that these resistant patients would benefit even more from cue exposure therapy (CET) targeting features associated with poor response (e.g. urge to binge in response to a cue and anxiety experienced in the presence of binge-related cues). We assessed the effectiveness of virtual reality-CET as a second-level treatment strategy for 64 patients with bulimia nervosa and binge eating disorder who had been treated with limited results after using a structured CBT programme, in comparison with A-CBT. The significant differences observed between the two groups at post-treatment in dimensional (behavioural and attitudinal features, anxiety, food craving) and categorical (abstinence rates) outcomes highlighted the superiority of virtual reality-CET over A-CBT. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Decision-making in obesity without eating disorders: a systematic review and meta-analysis of Iowa gambling task performances

BACKGROUND

There is evidence that obesity is associated with impairments in executive functions, such as deficits in decision-making, planning or problem solving, which might interfere with weight loss in obese individuals. We performed a systematic review and meta-analysis of decision-making abilities, as measured with the Iowa gambling task (IGT), in obesity without eating disorders.

METHODS

A systematic search was conducted to identify studies comparing IGT performances between groups of obese patients without eating disorders and groups of healthy control groups. The standardized mean differences were calculated for the total IGT scores and for the course of IGT scores. Meta-regression analyses were performed to explore the influence of clinical variables on standardized mean differences.

RESULTS

Total IGT scores were significantly lower in obese patients compared with normal-weight healthy controls. IGT performances did not differ between groups for the first trials of the task. Significant effect sizes for the last trials of the task were subjected to a high degree of heterogeneity.

CONCLUSION

Risky decision-making is impaired in obesity. The clinical importance of non-food-related decision-making impairments remains to be assessed especially in terms of consequences in daily life or the achievement of weight loss. This meta-analysis has been registered in the Prospero database (CRD42016037533).

Frequency of Consuming Foods Predicts Changes in Cravings for Those Foods During Weight Loss: The POUNDS Lost Study

OBJECTIVE

Food cravings are thought to be the result of conditioning or pairing hunger with consumption of certain foods.

METHODS

In a 2-year weight loss trial, subjects were randomized to one of four diets that varied in macronutrient content. The Food Craving Inventory (FCI) was used to measure cravings at baseline and at 6 and 24 months. Food intake was also measured at those time points. To measure free-living consumption of food items measured in the FCI, items on the FCI were matched to the foods consumed from the food intake assessments. Secondarily, the amount of food consumed on food intake assessments from foods on the FCI was analyzed.

RESULTS

Three hundred and sixty-seven subjects with overweight and obesity were included. There was an association between change from baseline FCI item consumption and change in cravings at months 6 (P < 0.001) and 24 (P < 0.05). There was no association between change from baseline amount of energy consumed per FCI item and change in cravings.

CONCLUSIONS

Altering frequency of consuming craved foods is positively associated with cravings; however, changing the amount of foods consumed does not appear to alter cravings. These results support the conditioning model of food cravings and provide guidance on how to reduce food cravings.

A brief review of salient factors influencing adult eating behaviour

A better understanding of the factors that influence eating behaviour is of importance as our food choices are associated with the risk of developing chronic diseases such as obesity, CVD, type 2 diabetes or some forms of cancer. In addition, accumulating evidence suggests that the industrial food production system is a major contributor to greenhouse gas emission and may be unsustainable. Therefore, our food choices may also contribute to climate change. By identifying the factors that influence eating behaviour new interventions may be developed, at the individual or population level, to modify eating behaviour and contribute to society’s health and environmental goals. Research indicates that eating behaviour is dictated by a complex interaction between physiology, environment, psychology, culture, socio-economics and genetics that is not fully understood. While a growing body of research has identified how several single factors influence eating behaviour, a better understanding of how these factors interact is required to facilitate the developing new models of eating behaviour. Due to the diversity of influences on eating behaviour this would probably necessitate a greater focus on multi-disciplinary research. In the present review, the influence of several salient physiological and environmental factors (largely related to food characteristics) on meal initiation, satiation (meal size) and satiety (inter-meal interval) are briefly discussed. Due to the large literature this review is not exhaustive but illustrates the complexity of eating behaviour. The present review will also highlight several limitations that apply to eating behaviour research.

Overlapping Neural Endophenotypes in Addiction and Obesity

Impulsivity refers to a tendency to act rapidly without full consideration of consequences. The trait is thought to result from the interaction between high arousal responses to potential rewards and poor self-control. Studies have suggested that impulsivity confers vulnerability to both addiction and obesity. However, results in this area are unclear, perhaps due to the high phenotypic complexity of addictions and obesity. Focusing on impulsivity, the aim of this review is to tackle the putative overlaps between addiction and obesity in four domains: (1) personality research, (2) neurocognitive tasks, (3) brain imaging, and (4) clinical evidence. We suggest that three impulsivity-related domains are particularly relevant for our understanding of similarities between addiction and obesity: lower self-control (high Disinhibition/low Conscientiousness), reward sensitivity (high Extraversion/Positive Emotionality), and negative affect (high Neuroticism/Negative Emotionality). Neurocognitive studies have shown that obesity and addiction are both associated with increased impulsive decision-making and attention bias in response to drug or food cues, respectively. Mirroring this, obesity and different forms of addiction seem to exhibit similar alterations in functional MRI brain activity in response to reward processing and during self-control tasks. Overall, our review provides an integrative approach to understand those facets of obesity that present similarities to addictive behaviors. In addition, we suggest that therapeutic interventions targeting inhibitory control may represent a promising approach for the prevention and/or treatment of obesity.

Emotional Eating, Binge Eating and Animal Models of Binge-Type Eating Disorders

PURPOSE OF REVIEW

The objective of this paper is to review the role that hedonic factors, emotions and self-regulation systems have over eating behaviours from animal models to humans.

RECENT FINDINGS

Evidence has been found to suggest that for some high-risk individuals, obesity/binge eating may develop as an impulsive reaction to negative emotions that over time becomes a compulsive habit. Animal models highlight the neural mechanisms that might underlie this process and suggest similarities with substance use disorders. Emotional difficulties and neurobiological factors have a role in the aetiology of eating and weight disorders. Precise treatments targeted at these mechanisms may be of help for people who have difficulties with compulsive overeating.

Improving Assessment of the Spectrum of Reward-Related Eating: The RED-13

A diversity of scales capture facets of reward-related eating (RRE). These scales assess food cravings, uncontrolled eating, addictive behavior, restrained eating, binge eating, and other eating behaviors. However, these scales differ in terms of the severity of RRE they capture. We sought to incorporate the items from existing scales to broaden the 9-item Reward-based Eating Drive scale (RED-9; Epel et al., 2014), which assesses three dimensions of RRE (lack of satiety, preoccupation with food, and lack of control over eating), in order to more comprehensively assess the entire spectrum of RRE. In a series of 4 studies, we used Item Response Theory models to consider candidate items to broaden the RED-9. Studies 1 and 2 evaluated the abilities of additional items from existing scales to increase the RED-9's coverage across the spectrum of RRE. Study 3 evaluated candidate items identified in Studies 1 and 2 in a new sample to assess the extent to which they accounted for more variance in areas less well-covered by the RED-9. Study 4 tested the ability of the RED-13 to provide consistent coverage across the range of the RRE spectrum. The resultant RED-13 accounted for greater variability than the RED-9 by reducing gaps in coverage of RRE in middle-to-low ranges. Like the RED-9, the RED-13 was positively correlated with BMI. The RED-13 was also positively related to a diagnosis of type 2 diabetes as well as cravings for sweet and savory foods. In summary, the RED-13 is a brief self-report measure that broadly captures the spectrum of RRE and may be a useful tool for identifying individuals at risk for overweight or obesity.

Validation of prospective portion size and latency to eat as measures of reactivity to snack foods

In experimental studies that investigate reactivity to the sight and smell of highly palatable snack foods, ad libitum food intake is commonly used as a behavioural outcome measure. However, this measure has several drawbacks. The current study investigated two intake-related measures not yet validated for food cue exposure research involving common snack foods: prospective portion size and latency to eat. We aimed to validate these measures by assessing prospective portion size and eating latencies in female undergraduate students who either underwent snack food exposure or a control exposure. Furthermore, we correlated prospective portion size and latency to eat with commonly used measures of food cue reactivity, i.e., self-reported desire to eat, salivation, and ad libitum food intake. Results showed increases in prospective portion size after food cue exposure but not after control exposure. Latency to eat did not differ between the two conditions. Prospective portion size correlated positively with desire to eat and food intake, and negatively with latency to eat. Latency to eat was also negatively correlated with desire to eat and food intake. It is concluded that the current study provides initial evidence for the prospective portion size task as a valid measure of reactivity to snack foods in a Dutch female and mostly healthy weight student population.

Mindfulness Reduces Reactivity to Food Cues: Underlying Mechanisms and Applications in Daily Life

PURPOSE OF REVIEW

Mindfulness-based interventions are becoming increasingly popular as a means to facilitate healthy eating. We suggest that the decentering component of mindfulness, which is the metacognitive insight that all experiences are impermanent, plays an especially important role in such interventions. To facilitate the application of decentering, we address its psychological mechanism to reduce reactivity to food cues, proposing that it makes thoughts and simulations in response to food cues less compelling. We discuss supporting evidence, applications, and challenges for future research.

RECENT FINDINGS

Experimental and correlational studies consistently find that the adoption of a decentering perspective reduces subjective cravings, physiological reactivity such as salivation, and unhealthy eating.

SUMMARY

We suggest that the decentering perspective can be adopted in any situation to reduce reactivity to food cues. Considering people's high exposure to food temptations in daily life, this makes it a powerful tool to empower people to eat healthily.