Validation of a laboratory craving assessment and evaluation of 4 different interventions on cravings among adults with overweight or obesity.

Food cue reactivity (FCR) is an appetitive trait associated with overeating and weight gain. We developed a laboratory craving assessment to objectively evaluate cognitive aspects of FCR. This study examined the preliminary construct and criterion validity of this craving assessment and evaluated 4 different interventions, 2 of which incorporated cue-exposure treatment for food, on craving over treatment and follow-up. 271 treatment-seeking adults with overweight/obesity (body mass index = 34.6[5.2]; age = 46.5[11.8]; 81.2% female; 61.6% non-Latinx White) completed the Food Cue Responsivity Scale and the laboratory craving assessment, during which they alternated holding and smelling a highly craved food and provided craving ratings over 5 min. Participants were subsequently randomized to 26 treatment sessions over 12-months of ROC, Behavioral Weight Loss (BWL), a combined arm (ROC+) and an active comparator (AC), and repeated the craving assessment at post-treatment and 12-month follow-up. Linear mixed-effects models assessed associations between trial type (holding vs. smelling), trial number, pre-treatment FCR, treatment arm, assessment time point, and craving. Cravings were greater when smelling vs. holding food (b = 0.31, p < 0.001), and cravings decreased over time (b = -0.02, p < 0.001). Participants with higher pre-treatment FCR reported elevated cravings (b = 0.29, p < 0.001). Longitudinally, we observed a significant 3-way interaction in which treatment arm modified the relationship between pre-treatment FCR and craving over time (F(17,5122) = 6.88, p < 0.001). An attenuated FCR-craving relationship was observed in ROC+ and BWL from baseline to post-treatment but was only sustained in BWL at follow-up. This attenuation was also observed in ROC and AC from post-treatment to follow-up. The preliminary validity of this laboratory craving assessment was supported; however, greater craving reductions over time in ROC/ROC+ compared to BWL and AC were not consistently observed, and thus do not appear to fully account for the moderating effect of FCR on weight losses observed in the trial.

Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging.

Acute exercise suppresses appetite and alters food-cue reactivity, but the extent exercise-induced changes in cerebral blood flow (CBF) influences the blood-oxygen-level-dependent (BOLD) signal during appetite-related paradigms is not known. This study examined the impact of acute running on visual food-cue reactivity and explored whether such responses are influenced by CBF variability. In a randomised crossover design, 23 men (mean ± SD: 24 ± 4 years, 22.9 ± 2.1 kg/m2 ) completed fMRI scans before and after 60 min of running (68% ± 3% peak oxygen uptake) or rest (control). Five-minute pseudo-continuous arterial spin labelling fMRI scans were conducted for CBF assessment before and at four consecutive repeat acquisitions after exercise/rest. BOLD-fMRI was acquired during a food-cue reactivity task before and 28 min after exercise/rest. Food-cue reactivity analysis was performed with and without CBF adjustment. Subjective appetite ratings were assessed before, during and after exercise/rest. Exercise CBF was higher in grey matter, the posterior insula and in the region of the amygdala/hippocampus, and lower in the medial orbitofrontal cortex and dorsal striatum than control (main effect trial p ≤ .018). No time-by-trial interactions for CBF were identified (p ≥ .087). Exercise induced moderate-to-large reductions in subjective appetite ratings (Cohen's d = 0.53-0.84; p ≤ .024) and increased food-cue reactivity in the paracingulate gyrus, hippocampus, precuneous cortex, frontal pole and posterior cingulate gyrus. Accounting for CBF variability did not markedly alter detection of exercise-induced BOLD signal changes. Acute running evoked overall changes in CBF that were not time dependent and increased food-cue reactivity in regions implicated in attention, anticipation of reward, and episodic memory independent of CBF.

The effect of hunger state on hypothalamic functional connectivity in response to food cues.

The neural underpinnings of the integration of internal and external cues that reflect nutritional status are poorly understood in humans. The hypothalamus is a key integrative area involved in short- and long-term energy intake regulation. Hence, we examined the effect of hunger state on the hypothalamus network using functional magnetic resonance imaging. In a multicenter study, participants performed a food cue viewing task either fasted or sated on two separate days. We evaluated hypothalamic functional connectivity (FC) using psychophysiological interactions during high versus low caloric food cue viewing in 107 adults (divided into four groups based on age and body mass index [BMI]; age range 24-76 years; BMI range 19.5-41.5 kg/m2 ). In the sated compared to the fasted condition, the hypothalamus showed significantly higher FC with the bilateral caudate, the left insula and parts of the left inferior frontal cortex. Interestingly, we observed a significant interaction between hunger state and BMI group in the dorsolateral prefrontal cortex (DLPFC). Participants with normal weight compared to overweight and obesity showed higher FC between the hypothalamus and DLPFC in the fasted condition. The current study showed that task-based FC of the hypothalamus can be modulated by internal (hunger state) and external cues (i.e., food cues with varying caloric content) with a general enhanced communication in the sated state and obesity-associated differences in hypothalamus to DLPFC communication. This could potentially promote overeating in persons with obesity.

Emotional food-cue-reactivity in anorexia nervosa and bulimia nervosa: An electroencephalography study.

OBJECTIVE: Food-cue-reactivity entails neural and experiential responses to the sight and smell of attractive foods. Negative emotions can modulate such cue-reactivity and this might be central to the balance between restrictive versus bulimic symptomatology in Anorexia Nervosa (AN) and Bulimia Nervosa (BN). METHOD: Pleasantness ratings and electrocortical responses to food images were measured in patients with AN (n = 35), BN (n = 32) and matched healthy controls (HC, n = 35) in a neutral state and after idiosyncratic negative emotion induction while electroencephalography (EEG) was recorded. The EEG data were analyzed using a mass testing approach. RESULTS: Individuals with AN showed reduced pleasantness for foods compared to objects alongside elevated widespread occipito-central food-object discrimination between 170 and 535 ms, indicative of strong neural cue-reactivity. Food-object discrimination was further increased in the negative emotional condition between 690 and 1200 ms over centroparietal regions. Neither of these effects was seen in individuals with BN. DISCUSSION: Emotion modulated food-cue-reactivity in AN might reflect a decreased appetitive response in negative mood. Such specific (emotion-)regulatory strategies require more theoretical work and clinical attention. The absence of any marked effects in BN suggests that emotional cue-reactivity might be less prominent in this group or quite specific to certain emotional contexts or food types. PUBLIC SIGNIFICANCE: Negative affectivity is a risk factor for the development of eating disorders and individuals with eating disorders experience problems with emotion regulation. To better understand the effects of negative emotions, the present study investigated how they affected neural correlates of food perception in anorexia nervosa and bulimia nervosa.

Prone to food in bad mood-Emotion-potentiated food-cue reactivity in patients with binge-eating disorder.

OBJECTIVE: Theories on emotional eating are central to our understanding of etiology, maintenance, and treatment of binge eating. Yet, findings on eating changes under induced negative emotions in binge-eating disorder (BED) are equivocal. Thus, we studied whether food-cue reactivity is potentiated under negative emotions in BED, which would point toward a causal role of emotional eating in this disorder. METHODS: Patients with BED (n = 24) and a control group without eating disorders (CG; n = 69) completed a food picture reactivity task after induction of negative versus neutral emotions. Food-cue reactivity (self-reported food pleasantness, desire to eat [DTE], and corrugator supercilii muscle response, electromyogram [EMG]) was measured for low- and high-caloric food pictures. RESULTS: Patients with BED showed emotion-potentiated food-cue reactivity compared to controls: Pleasantness and DTE ratings and EMG response were increased in BED during negative emotions. This was independent of caloric content of the images. CONCLUSIONS: Food-cue reactivity in BED was consistent with emotional eating theories and points to a heightened response to all foods regardless of calorie content. The discrepancy of appetitive ratings with the aversive corrugator response points to ambivalent food responses under negative emotions in individuals with BED.

Acute vagus nerve stimulation does not affect liking or wanting ratings of food in healthy participants.

The vagus nerve plays a vital role in the regulation of food intake and vagal afferent signals may help regulate food cue reactivity by providing negative homeostatic feedback. Despite strong evidence from preclinical studies on vagal afferent "satiety" signals in guiding food intake, evidence from human studies is largely inconclusive to date. Here, we investigated the acute effects of left or right transcutaneous auricular vagus nerve stimulation (taVNS) on subjective ratings of wanting and liking of various food and non-food items in 82 healthy participants (46 women, MBMI = 23.1 kg/m2). In contrast to previous reports in patients with depression, we found moderate to anecdotal evidence supporting the absence of taVNS-induced changes in food ratings. To test whether the absence of taVNS effects on food ratings is due to heterogeneity in the sample, we conducted post hoc subgroup analyses by splitting the data according to stimulation side and sex (between-subject factors) as well as caloric density, perceived healthiness, and flavor (sweet vs. savory) of the food (within-subject factors). This multiverse analysis largely supported the absence of taVNS-induced changes since the strongest subgroup effects provided only anecdotal evidence in favor of taVNS-induced changes. We conclude that acute taVNS only has a marginal effect on subjective ratings of food, suggesting that it is an unlikely mechanism for the reported long-term effects of VNS on body weight. In light of an absence of acute taVNS effects on conscious food liking and wanting, our results call for future research on the correspondence between acute and chronic effects of vagal afferent stimulation.

Uncontrolled eating in healthy women has limited influence on food cue reactivity and food-related inhibitory control.

Uncontrolled eating-in the general population-is characterized by overeating, hedonic hunger and being drawn towards palatable foods. Theoretically, it is the result of a strong food reward signal in relation to a poor ability to exert inhibitory control. How food consumption influences inhibitory control and food cue sensitivity, and how this relates to the continued urge to eat, remains unclear. We used fMRI in order to investigate the neural mechanism underlying food cue reactivity and food-specific response inhibition (go-nogo task), by comparing women reporting high (n = 21) versus low/average (n = 19) uncontrolled eating across two sessions: during an inter-meal state and after consumption of a high-caloric snack. We found no effects of individual differences in uncontrolled eating, food consumption, nor their interaction on food cue reactivity. Differences in uncontrolled eating and food consumption did interact in modulating activity in an occipital-parietal network, extending from left lateral superior occipital cortex to visual cortex, cuneal cortex, and precuneus during response inhibition of non-food stimuli, areas previously associated with successful nogo-vs. go-trials. Yet, behavioural performance on the go-nogo task was not modulated by uncontrolled eating nor food consumption. Women with a low/average tendency for uncontrolled eating may need more cognitive resources to support successful response inhibition of non-food stimuli during food 'go' blocks in an inter-meal state, whereas women with a high tendency for uncontrolled eating showed this after food consumption. However, considering current and previous findings, it seems that individual differences in uncontrolled eating in healthy women have only limited influence on food cue reactivity and food-related inhibitory control.

Associations between ghrelin and leptin and neural food cue reactivity in a fasted and sated state.

Food cue exposure can trigger eating. Food cue reactivity (FCR) is a conditioned response to food cues and includes physiological responses and activation of reward-related brain areas. FCR can be affected by hunger and weight status. The appetite-regulating hormones ghrelin and leptin play a pivotal role in homeostatic as well as hedonic eating. We examined the association between ghrelin and leptin levels and neural FCR in the fasted and sated state and the association between meal-induced changes in ghrelin and neural FCR, and in how far these associations are related to BMI and HOMA-IR. Data from 109 participants from three European centers (age 50±18 y, BMI 27±5 kg/m2) who performed a food viewing task during fMRI after an overnight fast and after a standardized meal were analyzed. Blood samples were drawn prior to the viewing task in which high-caloric, low-caloric and non-food images were shown. Fasting ghrelin was positively associated with neural FCR in the inferior and superior occipital gyrus in the fasted state. This was partly attributable to BMI and HOMA-IR. These brain regions are involved in visual attention, suggesting that individuals with higher fasting ghrelin have heightened attention to food cues. Leptin was positively associated with high calorie FCR in the medial prefrontal cortex (PFC) in the fasted state and to neural FCR in the left supramarginal gyrus in the fasted versus sated state, when correcting for BMI and HOMA-IR, respectively. This PFC region is involved in assessing anticipated reward value, suggesting that for individuals with higher leptin levels high-caloric foods are more salient than low-caloric foods, but foods in general are not more salient than non-foods. There were no associations between ghrelin and leptin and neural FCR in the sated state, nor between meal-induced changes in ghrelin and neural FCR. In conclusion, we show modest associations between ghrelin and leptin and neural FCR in a relatively large sample of European adults with a broad age and BMI range. Our findings indicate that people with higher leptin levels for their weight status and people with higher ghrelin levels may be more attracted to high caloric foods when hungry. The results of the present study form a foundation for future studies to test whether food intake and (changes in) weight status can be predicted by the association between (mainly fasting) ghrelin and leptin levels and neural FCR.

Reliability of neural food cue-reactivity in participants with obesity undergoing bariatric surgery: a 26-week longitudinal fMRI study.

Obesity is highly prevalent worldwide and results in a high disease burden. The efforts to monitor and predict treatment outcome in participants with obesity using functional magnetic resonance imaging (fMRI) depends on the reliability of the investigated task-fMRI brain activation. To date, no study has investigated whole-brain reliability of neural food cue-reactivity. To close this gap, we analyzed the longitudinal reliability of an established food cue-reactivity task. Longitudinal reliability of neural food-cue-induced brain activation and subjective food craving ratings over three fMRI sessions (T0: 2 weeks before surgery, T1: 8 weeks and T2: 24 weeks after surgery) were investigated in N = 11 participants with obesity. We computed an array of established reliability estimates, including the intraclass correlation (ICC), the Dice and Jaccard coefficients and similarity of brain activation maps. The data indicated good reliability (ICC > 0.6) of subjective food craving ratings over 26 weeks and excellent reliability (ICC > 0.75) of brain activation signals for the contrast of interest (food > neutral) in the caudate, putamen, thalamus, middle cingulum, inferior, middle and superior occipital gyri, and middle and superior temporal gyri and cunei. Using similarity estimates, it was possible to re-identify individuals based on their neural activation maps (73%) with a fading degree of accuracy, when comparing fMRI sessions further apart. The results show excellent reliability of task-fMRI neural brain activation in several brain regions. Current data suggest that fMRI-based measures might indeed be suitable to monitor and predict treatment outcome in participants with obesity undergoing bariatric surgery.

Rethinking Food Reward.

The conscious perception of the hedonic sensory properties of caloric foods is commonly believed to guide our dietary choices. Current and traditional models implicate the consciously perceived hedonic qualities of food as driving overeating, whereas subliminal signals arising from the gut would curb our uncontrolled desire for calories. Here we review recent animal and human studies that support a markedly different model for food reward. These findings reveal in particular the existence of subcortical body-to-brain neural pathways linking gastrointestinal nutrient sensors to the brain's reward regions. Unexpectedly, consciously perceptible hedonic qualities appear to play a less relevant, and mostly transient, role in food reinforcement. In this model, gut-brain reward pathways bypass cranial taste and aroma sensory receptors and the cortical networks that give rise to flavor perception. They instead reinforce behaviors independently of the cognitive processes that support overt insights into the nature of our dietary decisions.

Bad mood food? Increased versus decreased food cue reactivity in anorexia nervosa and bulimia nervosa during negative emotions.

OBJECTIVE: Emotion regulation difficulties in anorexia nervosa (AN) and bulimia nervosa (BN) might underlie bingeing and purging in BN, extreme fasting in AN, or combinations of these symptoms in binge-purge type AN. In this study, we tested for decreased food cue reactivity in response to negative emotions in AN, and the opposite pattern for BN. Furthermore, we explored subgroup differences (restrictive vs. binge-purging AN; history of AN in BN). METHOD: Patients with AN (n = 41), BN (n = 39), and matched controls (n = 70) completed an emotional eating questionnaire. In a laboratory experiment, we induced negative emotions and measured food cue reactivity (pleasantness, desire to eat (DTE), and corrugator muscle activity). RESULTS: AN reported emotional undereating, while BN reported emotional overeating. In the laboratory task, BN showed increased DTE and an appetitive corrugator response during negative emotions, selectively towards high-calorie foods. AN showed generalized reduced cue reactivity to high-calorie food regardless of emotional state. This pattern appears to be characteristic of restrictive AN, while cue reactivity of both BN subgroups pointed towards emotional overeating. CONCLUSIONS: The emotional over- versus undereating framework might help to explain bingeing and restricting along the anorectic-bulimic disorder spectrum, which calls for novel transdiagnostic theories and subgroup-specific treatments.

Liking and left amygdala activity during food versus nonfood processing are modulated by emotional context.

Emotions can influence our eating behaviors. Facing an acute stressor or being in a positive mood are examples of situations that tend to modify appetite. However, the question of how the brain integrates these emotion-related changes in food processing remains elusive. Here, we designed an emotional priming fMRI task to test if amygdala activity during food pictures differs depending on the emotional context. Fifty-eight female participants completed a novel emotional priming task, in which emotional images of negative, neutral, or positive situations were followed by pictures of either foods or objects. After priming in each trial, participants rated how much they liked the shown foods or objects. We analyzed how brain activity during the contrast "foods > objects" changed according to the emotional context-in the whole brain and in the amygdala. We also examined the potential effect of adiposity (i.e., waist circumference). We observed a higher difference between liking scores for foods and objects after positive priming than after neutral priming. In the left amygdala, activity in the contrast "foods > objects" was higher after neutral priming relative to negative priming. Waist circumference was not significantly related to this emotional priming effect on food processing. Our results suggest that emotional context alters food and nonfood perception, both in terms of liking scores and with regard to engagement of the left amygdala. Moreover, our findings indicate that emotional context has an impact on the salience advantage of food, possibly affecting eating behavior.

Food cue-elicited brain potentials change throughout menstrual cycle: Modulation by eating styles, negative affect, and premenstrual complaints.

BACKGROUND: While there is evidence for increased food intake and craving during the luteal phase, underlying mechanisms are incompletely understood. The present study investigated electrophysiological responses to food pictures as a function of menstrual cycle phase. In addition, the moderating effects of progesterone, eating behaviors (restraint, emotional, orthorexic), negative affect, and premenstrual complaints were explored. METHODS: Using a within-subject design, 35 free-cycling women watched and rated pictures of food (high and low caloric) and control items during the follicular, the ovulatory, and the luteal phase (counterbalanced), while EEG was recorded to examine the late positive potentials (LPP). Salivary gonadal hormones and affect were examined at each occasion. Eating behaviors and premenstrual complaints were assessed once. RESULTS: For parietal regions, average LPPs were comparable between cycle phases but slightly larger LPP amplitudes were elicited by high caloric food pictures as compared to the neutral category. Descriptively, both food categories elicited larger parietal LPPs than neutral pictures during the luteal phase. Analyses of LPPs for central-parietal regions showed no effect of picture category or cycle phase, except higher amplitudes in the right area during the luteal phase. During the luteal phase, progesterone and functional interference from premenstrual symptoms (but not age, BMI, picture ratings, affect, estradiol, or eating behaviors) significantly predicted larger parietal LPPs towards high caloric (but not low caloric) pictures. CONCLUSION: Our findings suggest a heightened food cue reactivity during the luteal phase, which may relate to higher ovarian hormone secretion and more functional impact of premenstrual symptoms. This research contributes to a better understanding of menstrual health and the identification of preventive strategies for premenopausal women.

The effects of imaginary eating on visual food cue reactivity: An event-related potential study.

Previous research has demonstrated that imagining consumption of a specific type of food helps individuals to consume less of that food. The present event-related potential study aimed at investigating the underlying neural correlates of this appetite-reducing strategy. A total of 86 women (mean age = 23.65 years) were randomly assigned to one of three imagination conditions. In each condition, they listened to a guided imagery script that either described the eating of 30 colorful button-shaped chocolates (M&Ms), the sorting of 30 M&Ms by color, or the sorting of 30 marbles by color. Subsequently to the imagery task, the participants were presented with images of M&Ms and marbles while their electroencephalogram and craving ratings were recorded. The results showed that imaginary eating did not reduce the appetitive value of M&M pictures. The M&M sorting group reported enhanced craving and showed increased late positivity toward M&M pictures (300-600 ms after picture onset) compared to the two other groups. The present findings indicate that the imagined handling of food increases food cue reactivity and that imaginary eating is not a reliable method to reduce appetite.

Is hunger important to model in fMRI visual food-cue reactivity paradigms in adults with obesity and how should this be done?

We considered 1) influence of self-reported hunger in behavioral and fMRI food-cue reactivity (fMRI-FCR) 2) optimal methods to model this. Adults (N = 32; 19-60 years; F = 21; BMI 30-39.9 kg/m2) participated in an fMRI-FCR task that required rating 240 images of food and matched objects for 'appeal'. Hunger, satiety, thirst, fullness and emptiness were measured pre- and post-scan (visual analogue scales). Hunger, satiety, fullness and emptiness were combined to form a latent factor (appetite). Post-vs. pre-scores were compared using paired t-tests. In mixed-effects models, appeal/fMRI-FCR responses were regressed on image (i.e. food/objects), with random intercepts and slopes of image for functional runs nested within subjects. Each of hunger, satiety, thirst, fullness, emptiness and appetite were added as covariates in 4 forms (separate models): 1) change; 2) post- and pre-mean; 3) pre-; 4) change and pre-. Satiety decreased (Δ = -13.39, p = 0.001) and thirst increased (Δ = 11.78, p = 0.006) during the scan. Changes in other constructs were not significant (p's > 0.05). Including covariates did not influence food vs. object contrast of appeal ratings/fMRI-FCR. Significant image X covariate interactions were observed in some fMRI models. However, including these constructs did not improve the overall model fit. While some subjective, self-reported hunger, satiety and related constructs may be moderating fMRI-FCR, these constructs do not appear to be salient influences on appeal/fMRI-FCR in people with obesity undergoing fMRI.

Effects of 3-week total meal replacement vs. typical food-based diet on human brain functional magnetic resonance imaging food-cue reactivity and functional connectivity in people with obesity.

OBJECTIVES: Calorie restriction via total meal replacement (TMR) results in greater reduction of food cravings compared to reduced-calorie typical diet (TD). Direct evidence of the impact of these interventions on human brain fMRI food-cue reactivity (fMRI-FCR) and functional connectivity is absent. We examined the effects of a 3-week 1120 kcal/d TMR intervention as compared to an iso-caloric TD intervention using an fMRI-FCR paradigm. METHODS: Thirty-two male and female subjects with obesity (19-60 years; 30-39.9 kg/m2) participated in a randomized two-group repeated measures dietary intervention study consisting of 1120 kcal/d from either 1) TMR (shakes), 2) TD (portion control). Pre-intervention and following the 3-week diet fMRI-FCR, functional connectivity, food cravings (Food Craving Inventory) and weight were considered. RESULTS: Compared to TD, TMR showed increased fMRI-FCR of the bilateral dorsolateral prefrontal (dlPFC), orbitofrontal, anterior cingulate, primary motor and left insular cortices and bilateral nucleus accumbens regions in the post-intervention state relative to the pre-intervention state. Compared to TD, TMR was also associated with negative modulation of fMRI-FCR of the nucleus accumbens, orbitofrontal cortex and amygdala by dlPFC. Reduced body weight (4.87 kg, P < 0.001), body fat (2.19 kg, P = 0.004) and overall food cravings (0.41, P = 0.047) were seen in the TMR group. In the TD group reduced body weight (2.37 kg, P = 0.004) and body fat (1.64 kg, P = 0.002) were noted. Weight loss was significantly greater in TMR versus TD (2.50 kg, P = 0.007). CONCLUSIONS: Greater weight loss and reduced cravings, coupled with stronger activations and potential negative modulation of the food reward related regions by the dlPFC during exposure to visual food cues is consistent with increased executive control in TMR vs. TD.

Academic stress and personality interact to increase the neural response to high-calorie food cues.

Psychosocial stress is associated with an increased intake of palatable foods and weight gain in stress-reactive individuals. Personality traits have been shown to predict stress-reactivity. However, it is not known if personality traits influence brain activity in regions implicated in appetite control during psychosocial stress. The current study assessed whether Gray's Behavioural Inhibition System (BIS) scale, a measure of stress-reactivity, was related to the activity of brain regions implicated in appetite control during a stressful period. Twenty-two undergraduate students participated in a functional magnetic resonance imaging (fMRI) experiment once during a non-exam period and once during final exams in a counter-balanced order. In the scanner, they viewed food and scenery pictures. In the exam compared with the non-exam condition, BIS scores related to increased perceived stress and correlated with increased blood-oxygen-level dependent (BOLD) response to high-calorie food images in regions implicated in food reward and subjective value, such as the ventromedial prefrontal cortex, (vmPFC) and the amygdala. BIS scores negatively related to the functional connectivity between the vmPFC and the dorsolateral prefrontal cortex. The results demonstrate that the BIS trait influences stress reactivity. This is observed both as an increased activity in brain regions implicated in computing the value of food cues and decreased connectivity of these regions to prefrontal regions implicated in self-control. This suggests that the effects of real life stress on appetitive brain function and self-control is modulated by a personality trait. This may help to explain why stressful periods can lead to overeating in vulnerable individuals.

Brain regions involved in ingestive behavior and related psychological constructs in people undergoing calorie restriction.

Human food intake is regulated by physiological energy homeostatic mechanisms and hedonic mechanisms. These are affected by both very short-term and longer-term calorie restriction (CR). To date, there are parallel discussions in the literature that fail to integrate across these disciplines and topics. First, much of the available neuroimaging research focusses on specific functional paradigms (e.g. reward, energy homeostasis). These paradigms often fail to consider more complex and inclusive models that examine how potential brain regions of interest interact to influence ingestion. Second, the paradigms used focus primarily on short-term CR (fasting) which has limited generalizability to clinical application. Finally, the behavioral literature, while frequently examining longer-term CR and related psychological constructs in the context of weight management (e.g. hedonic restraint, 'liking', 'wanting' and food craving), fails to adequately tie these phenomena to underlying neural mechanisms. The result is a less than complete picture of the brain's role in the complexity of the human experience of ingestion. This disconnect highlights a major limitation in the CR literature, where attempts are persistently made to exert behavioral control over ingestion, without fully understanding the complex bio behavioral systems involved. In this review we attempt to summarize all potential brain regions important for human ingestion, present a broad conceptual overview of the brain's multifaceted role in ingestive behavior, the human (psychological) experiences related to ingestion and to examine how these factors differ according to three forms of CR. These include short-term fasting, extended CR, and restrained eating. We aim to bring together the neuroimaging literature with the behavioral literature within a conceptual framework that may inform future translational research.

Greater anterior cingulate activation and connectivity in response to visual and auditory high-calorie food cues in binge eating: Preliminary findings.

Obese individuals show altered neural responses to high-calorie food cues. Individuals with binge eating [BE], who exhibit heightened impulsivity and emotionality, may show a related but distinct pattern of irregular neural responses. However, few neuroimaging studies have compared BE and non-BE groups. To examine neural responses to food cues in BE, 10 women with BE and 10 women without BE (non-BE) who were matched for obesity (5 obese and 5 lean in each group) underwent fMRI scanning during presentation of visual (picture) and auditory (spoken word) cues representing high energy density (ED) foods, low-ED foods, and non-foods. We then compared regional brain activation in BE vs. non-BE groups for high-ED vs. low-ED foods. To explore differences in functional connectivity, we also compared psychophysiologic interactions [PPI] with dorsal anterior cingulate cortex [dACC] for BE vs. non-BE groups. Region of interest (ROI) analyses revealed that the BE group showed more activation than the non-BE group in the dACC, with no activation differences in the striatum or orbitofrontal cortex [OFC]. Exploratory PPI analyses revealed a trend towards greater functional connectivity with dACC in the insula, cerebellum, and supramarginal gyrus in the BE vs. non-BE group. Our results suggest that women with BE show hyper-responsivity in the dACC as well as increased coupling with other brain regions when presented with high-ED cues. These differences are independent of body weight, and appear to be associated with the BE phenotype.

Approach bias and cue reactivity towards food in people with high versus low levels of food craving.

OBJECTIVE: Even though people suffering from high levels of food craving are aware of the negative consequences of binge eating, they cannot resist. Automatic action tendencies (i.e. approach bias) towards food cues that operate outside conscious control may contribute to this dysfunctional behavior. The present study aimed to examine whether people with high levels of food craving show a stronger approach bias for food than those with low levels of food craving and whether this bias is associated with cue-elicited food craving. METHOD: Forty-one individuals reporting either extremely high or extremely low levels of trait food craving were recruited via an online screening and compared regarding approach bias towards visual food cues by means of an implicit stimulus-response paradigm (i.e. the Food Approach-Avoidance Task). State levels of food craving were assessed before and after cue exposure to indicate food cue reactivity. RESULTS: As expected, high food cravers showed stronger automatic approach tendencies towards food than low food cravers. Also in line with the hypotheses, approach bias for food was positively correlated with the magnitude of change in state levels of food craving from pre-to post-cue exposure in the total sample. DISCUSSION: The findings suggest that an approach bias in early stages of information processing contributes to the inability to resist food intake and may be of relevance for understanding and treating dysfunctional eating behavior.