Caloric restriction in the presence of attractive food cues: External cues, eating, and weight

Hunger, Satiety, and Their Vulnerabilities

The psychological states of hunger and satiety play an important role in regulating human food intake. Several lines of evidence suggest that these states rely upon declarative learning and memory processes, which are based primarily in the medial temporal lobes (MTL). The MTL, and particularly the hippocampus, is unusual in that it is especially vulnerable to insult. Consequently, we examine here the impact on hunger and satiety of conditions that: (1) are central to ingestive behaviour and where there is evidence of MTL pathology (i.e., habitual consumption of a Western-style diet, obesity, and anorexia nervosa); and (2) where there is overwhelming evidence of MTL pathology, but where ingestive behaviour is not thought central (i.e., temporal lobe epilepsy and post-traumatic stress disorder). While for some of these conditions the evidence base is currently limited, the general conclusion is that MTL impairment is linked, sometimes strongly, to dysfunctional hunger and satiety. This focus on the MTL, and declarative learning and memory processes, has implications for the development of alternative treatment approaches for the regulation of appetite.

The Relationship between Occupational Fatigue and Well-Being: The Moderating Effect of Unhealthy Eating Behaviour

Tech giants are large, well-known internet and technology companies. Employees of such companies are generally expected to work fast and for long periods of time, causing them to experience high occupational fatigue. The relationship between occupational fatigue and well-being is complex. Furthermore, in the context of the workplace, unhealthy eating behaviour may be used as a mechanism to cope with fatigue and stress. This study explored the relationship between occupational fatigue, well-being and unhealthy eating behaviour within this specific professional population. Study 1 used qualitative research methods, in which in-depth interviews were conducted with staff working at 13 tech giants in Shenzhen, China (N = 50). The findings revealed that work-related stress and occupational fatigue are common among employees working for tech giants. Additionally, factors such as unhealthy eating behaviour, workload, working hours and workplace interpersonal relationships were found to influence occupational well-being. Study 2 involved a cross-sessional survey of 237 employees of tech giants. The results indicated that occupational fatigue negatively impacts occupational well-being and that unhealthy eating behaviours play a moderating role between occupational fatigue and occupational well-being. These findings highlight the significance of adopting appropriate measures to improve the situation and cope with the effects of occupational fatigue by managing unhealthy eating behaviours.

Eliciting real cravings with virtual food: Using immersive technologies to explore the effects of food stimuli in virtual reality

In this paper, we explore the current technical possibilities of eating in virtual reality (VR) and show how this could be used to influence eating behaviors. Cue-based exposure therapy is a well-known method used to treat eating disorders. There are several benefits to using VR in combination with cue-based therapy. However, before VR-based cue-exposure can be used for therapeutic purposes, the ability of the VR environment to elicit craving responses in participants must be assessed. This was the objective of the first part of the study, where we assessed whether our VR environment elicited food craving responses in participants. Results showed that our VR environment elicited food craving responses: Salivation Magnitude, Food Craving State and Urge to Eat was significantly different from the neutral baseline. In addition, results showed that food cravings measured through the salivation magnitude in response to the virtual condition were not significantly different from the real condition, thus showing that VR had a comparable effect on producing food cravings. The second part of the study was conducted to determine whether the addition of olfactory and interaction cues in VR increased the development of food cravings. The results of this part showed that adding synthetic olfactory cues, paired with visual cues, to our system, provided a significant further increase in food cravings. Our results demonstrate that the use of food cues in VR can increase the development of food cravings and that it is possible to provide a simple yet convincing eating experience in VR. Inevitably, food interaction in VR is still underexplored territory and further research is needed to improve utility and application in disciplines related to food and eating.

Challenging inhibitory control with high- and low-calorie food: A behavioural and TMS study

Most people are often tempted by their impulses to "indulge" in high-calorie food, even if this behaviour is not consistent with their goal to control weight in the long term and might not be healthy. The outcome of this conflict is strongly dependent on inhibitory control. It has already been reported that individuals with weaker inhibitory control consume more high-calorie food, are more often unsuccessful dieters, overweight or obese compared to people with more effective inhibitory control. In the present study, we aimed at investigating inhibitory control in the context of human eating behaviour. A sample of 20 healthy normal-weight adults performed a 50% probability visual affective Go/NoGo task involving food (high- and low-calorie) and non-food images as stimuli. Single-pulse transcranial magnetic stimulation (TMS) was administered over the right primary motor cortex (M1) either 300 ms after image presentation to measure corticospinal excitability during the different stimulus categories or 300 ms after the appearance of a fixation point, as a control stimulation condition. The experimental session consisted of a food target and a non-food target block. Behavioural outcomes showed a natural implicit inclination towards high-calorie food in that participants were faster and more accurate compared to the other categories. This advantage was selectively deleted by TMS, which slowed down reaction times. MEPs did not differ according to the stimulus category, but, as expected, were bigger for Go compared to NoGo trials. Participants judged high-calorie food also as more appetising than low-calorie food images. Overall, our results point to a differential modulation when targeting inhibitory control, in favour of the more palatable food category (high-calorie). Present data suggest that the activity of the motor system is modulated by food nutritional value, being more engaged by appetising food. Future work should explore to what extent these processes are affected in patients with eating disorders and should aim to better characterise the related dynamics of cortical connectivity within the motor network.

Adherence to a caloric budget and body weight change vary by season, gender, and BMI: An observational study of daily users of a mobile health app

Objective

Self-monitoring, one of the most important behaviors for successful weight loss, can be facilitated through mobile health applications (mHealth apps). Therefore, it is of interest to determine whether consistent users of these apps succeed in achieving their weight goals. This study used data from an mHealth app that enabled tracking of caloric intake, body weight, and physical activity and provided a caloric budget depending on weight goal. The primary objective was to evaluate adherence to caloric budget and body weight change among the most consistent (i.e., daily) trackers of caloric intake over a calendar year (n = 9372, 50% male).

Methods

Gender-stratified linear mixed models were conducted to examine the effects of quarter of year (Q1-Q4 as season proxies) and body mass index (BMI) group (normal weight, overweight, obesity) on adherence to a caloric budget (kcal/day). Change in body weight was analyzed using a subset of users (n = 5808) who entered their weight in the app at least once per week, once per month, or once in Q1 and Q4. Physical activity entries were evaluated in exploratory analyses.

Results

Only users with obesity met their caloric budget in Q1. Deviation from budget increased for all groups from Q1 to Q2 (mean change[±standard error of the mean]: +23.7[±1.8] and +39.7[±2.2] kcal/day for female and male users, p < 0.001), was stable between Q2 and Q3, and fluctuated thereafter depending on gender and BMI, with greater deviation among males with overweight. Users with obesity with weight entries at least once per month lost the most weight (-6.1[±0.3] and -4.5[±0.3] kg for females and males, p < 0.001). Physical activity was highest in the summer months.

Conclusions

Among consistent calorie trackers, adherence to a caloric budget and body weight vary by season, gender, and BMI. Self-monitoring of body weight in addition to calorie tracking may lead to improved weight loss outcomes.

Improved food Go/No-Go scores after transcranial direct current stimulation (tDCS) to prefrontal cortex in a randomized trial

OBJECTIVE

Reduced dorsolateral prefrontal cortex (dlPFC) activity and inhibitory control may contribute to obesity. The study objective was to assess effects of repeated transcranial direct current stimulation (tDCS) on food Go/No-Go (GNG), food Stroop performance, and snack food intake.

METHODS

Twenty-nine individuals with obesity (12 male; mean [SD], age 42 [11] years; BMI 39 [8]) participated in a combined inpatient/outpatient randomized parallel-design trial and received 15 sessions of anodal or sham tDCS to the left dlPFC. Food-related inhibitory control (GNG), attentional bias (Stroop), and snack food intake were assessed at baseline, completion of inpatient sessions (day 7), and follow-up (day 31).

RESULTS

GNG performance improved in the anodal group by day 31, compared with sham (p = 0.01), but Stroop scores did not differ by intervention. Greater snack food intake was associated with lower GNG scores (p = 0.01), driven by the sham group (p < 0.001) and higher food and palatable bias scores on the Stroop (all p = 0.02) across both groups. Changes on tasks were not associated with changes in intake.

CONCLUSIONS

Anodal tDCS to the left dlPFC improved performance on a food-related inhibitory control task, providing evidence of potential for therapeutic benefit of neuromodulation in areas controlling executive function. Results showed that tDCS to the dlPFC reduced snack food intake and hunger; however, underlying neurocognitive mechanisms remain uncertain.

Exploring Mindfulness and Mindful Eating and Visual Attention Towards Food Cues: Preliminary Findings

Continual exposure to energy dense foods is suggested to promote overeating and obesity. The aim of the present research was to explore whether or not mindfulness could reduce visual attention towards food cues. In two laboratory studies, participants with a normal weight range completed an eye-tracking paradigm, and their eye-movements were recorded. In study 1, participants were exposed to either mindfulness meditation or a control condition, and their eye-movements towards low energy density (LED) vs high energy density (HED) food cues were measured. In study 2, participants were assigned to a mindful eating condition using a Mindful Construal Diary (MCD) or a control condition, and their eye-movements towards LED or HED food vs. non-food cues were recorded. In study 1, participants in the mindfulness meditation condition had greater attention duration towards LED food cues, whilst those in the control condition exhibited greater attention duration towards HED food cues. In study 2, there were no significant differences in the maintenance of attentional biases towards food cues between the two conditions. Mindfulness meditation may be beneficial in increasing attention towards LED food cues. Future research should further explore the effect of mindfulness and mindful eating on visual attention towards food cues with people who suffer from excess weight or have obesity, and also within naturalistic settings.

Influencing Factors for Sustainable Dietary Transformation—A Case Study of German Food Consumption

In a case study of Germany, we examine current food consumption along the three pillars of sustainability to evaluate external factors that influence consumers’ dietary decisions. We investigate to what extent diets meet nutritional requirements (social factor), the diets’ environmental impact (ecological factor), and the food prices’ influence on purchasing behavior (economic factor). For this, we compare two dietary recommendations (plant-based, omnivorous) with the status quo, and we examine different consumption styles (conventional, organic produce). Additionally, we evaluate 1446 prices of food items from three store types (organic store, supermarket, and discounter). With this, we are able to evaluate and compare 30 different food baskets along their health, environmental, and economic impact. Results show that purchasing decisions are only slightly influenced by health-related factors. Furthermore, few consumers align their diet with low environmental impact. In contrast, a large share of consumers opt for cheap foods, regardless of health and environmental consequences. We find that price is, arguably, the main factor in food choices from a sustainability standpoint. Action should be taken by policy makers to financially incentivize consumers in favor of healthy and environmentally friendly diets. Otherwise, the status quo further drives especially underprivileged consumers towards unhealthy and environmentally damaging consumption.

Food Attention Bias: appetite comes with eating

OBJECTIVE

Cognitive interventions may be effective in weight loss. The purpose of this study was to assess if cognitive reappraisal (CR; reframing the meaning of a stimulus in order to change the resulting emotional response), can reduce food attentional bias (FAB) using the Visual Dot Probe (VDP) paradigm.

METHOD

126 participants (age 27 ± 5.8) were randomly assigned either to a CR or to a control (CN) group. After assessing baseline VDP levels for FAB, participants either wrote sentences that discourage eating fattening food or neutral sentences. Next, all participants performed the VDP post intervention. Participants also self-reported on disordered eating behaviors and their height and weight were charted. We hypothesized that CR would reduce FAB and that disordered eating would moderate the association between group and FAB.

RESULTS

FAB decreased post intervention, specifically in the CR group. The bulimia sub-scale showed an interaction between bulimic eating, time and group. Among those who were high on the bulimia scale, the CR group showed lower FAB post-intervention compared to the CN group.

DISCUSSION

This study suggests that CR may decrease the attentional bias toward high-calorie food compared to other strategies in the general population and among people with high bulimia measures, in particular. Obesity has a negative impact on many aspects of life and much research is dedicated to trying to better understand behaviors concerning obesity. People are prone to focus their attention on things that are of importance to them, such as food. When people focus their attention on food, we call this Food Attention Bias (FAB). Cognitive reappraisal (CR) interventions involve the person's conscious cognitive change of the meaning of the situation aiming to consequently change the emotional response to it, such as saying to yourself "I shouldn't eat this because I don't want to get fat". CR has been found to be helpful in lowering FAB using brain imagining techniques but has not yet been studied in cognitive processes. Our study used a Visual dot probe paradigm (VDP) to assess the efficacy of CR on lowering FAB. Two groups, one using CR and a control group were assessed twice on FAB, using the VDP paradigm. Compared to the normal condition, the CR intervention helped reduce FAB. This reduction was especially significant for people with a higher tendency for bulimic behavior. The VDP paradigm, utilizing CR. can be expanded to help build an intervention aimed at reducing FAB over time. This, in turn might bring to weight reduction. People with bulimic tendencies might especially benefit from CR interventions when dealing with weight loss.

Commentary on: "What is restrained eating and how do we identify it?": Unveiling the elephant in the room

This paper is a commentary on Polivy, Herman and Mills' (2020) article, entitled "What is restrained eating and how do we identify it?". Polivy et al.'s paper makes a useful contribution by providing guidelines to researchers for choosing the most appropriate measure of restraint for their research questions. However, the authors assume that restrained eating can be appropriately conceptualized as a trait, an assumption I question. They also assume that restrained eating has a causal influence on the outcomes (e.g., counterregulatory eating, negative affect eating, binge eating) with which it has been associated, which I also question. Finally, they ignored a second prominent model for conceptualizing dieting behavior, the Three-Factor Model of Dieting. The Three-Factor Model decomposes the construct of restrained eating into two types of dieting (current weight loss dieting and weight suppression) that do appear to be causally related to eating control and one type (restrained eating to avoid excessive consumption) that modulates likelihood of overeating but does not cause it. I conclude by noting that scientific progress is best served by promoting, not avoiding, discussion and debate about a multiplicity of perspectives on topics of interest, especially when incompatible hypotheses and data exist on such topics.

Investigating the Effect of Use and Social Cues in Food Advertisements on Attention, Feelings of Social Support, and Purchase Intention

In an effort to understand how different types of food cues in food ads are automatically encouraging unhealthy eating behaviors, the current study examined how the presence of actual food consumption behaviors (use cues) and presence of multiple individuals indorsing food products (social cues) in fast food ads would influence individual attentional and behavioral responses. A use cue (2) x social cue (2) x repetition (3) fully within-subjects factorial design experiment with young adults (N = 164) was conducted. Findings demonstrated that participants paid greater attention to the fast food ads which contained multiple people (group cue) eating the advertised food products (use cue) when compared to other types of fast food ads. In addition, participants also self-reported greater social support and purchase intention when seeing use and group cues in ads. Understanding how these cues function in food advertising to encourage unhealthy eating may help health practitioners and individuals create more helpful intervention strategies. Further, applying these marketing tactics to ads for food products that are healthier (i.e., less energy dense and more nutrient dense) may help to maximize healthy food palatability, thereby increasing motivation for viewers to make autonomous decisions about eating healthier.

Is obesity related to enhanced neural reactivity to visual food cues? A review and meta-analysis

Theoretical work suggests that obesity is related to enhanced incentive salience of food cues. However, evidence from both behavioral and neuroimaging studies on the topic is mixed. In this work we review the literature on cue reactivity in obesity and perform a preregistered meta-analysis of studies investigating effects of obesity on brain responses to passive food pictures viewing. Further, we examine whether age influences brain responses to food cues in obesity. In the meta-analysis we included 13 studies of children and adults that investigated group differences (obese vs. lean) in responses to food vs. non-food pictures viewing. While we found no significant differences in the overall meta-analysis, we show that age significantly influences brain response differences to food cues in the left insula and the left fusiform gyrus. In the left insula, obese vs. lean brain differences in response to food cues decreased with age, while in the left fusiform gyrus the pattern was opposite. Our results suggest that there is little evidence for obesity-related differences in responses to food cues and that such differences might be mediated by additional factors that are often not considered.

Influence of hunger on attentional engagement with and disengagement from pictorial food cues in women with a healthy weight

Because of inconsistencies in the field of attentional bias to food cues in eating behavior, this study aimed to re-examine the assumption that hungry healthy weight individuals have an attentional bias to food cues, but satiated healthy weight individuals do not. Since attentional engagement and attentional disengagement have been proposed to play a distinct role in behavior, we used a performance measure that is specifically designed to differentiate between these two attentional processes. Participants were healthy weight women who normally eat breakfast. In the satiated condition (n = 54), participants were instructed to have breakfast just before coming to the lab. In the fasted condition (n = 50), participants fasted on average 14 h before coming into the lab. Satiated women showed no stronger attentional engagement or attentional disengagement bias to food cues than to neutral cues. Fasted women did show stronger attentional engagement to food cues than to neutral cues that were shown briefly (100 ms). They showed no bias in attentional engagement to food cues that were shown longer (500 ms) or in attentional disengagement from food cues. These findings are in line with the assumption that healthy weight individuals show an attentional bias to food cues when food stimuli are motivationally salient. Furthermore, the findings point to the importance of differentiating between attentional engagement and attentional disengagement.

Food-Related Attentional Bias in Individuals with Normal Weight and Overweight: A Study with a Flicker Task

The primary purpose of the present study was to investigate attentional biases for food-related stimuli in individuals with overweight and normal weight using a flicker paradigm. Specifically, it was tested whether attention allocation processes differ between individuals with overweight and normal weight using transient changes of food-related and neutral pictures. Change detection latencies in objects of central interest (CI) or objects of marginal interest (MI) were measured as an index of attention allocation in a sample of fifty-three students with overweight/obesity and sixty students with normal weight during a flicker paradigm with neutral, hypercaloric and hypocaloric food pictures. Both groups of participants showed an attentional bias for food-related pictures as compared to neutral pictures. However, the bias was larger in individuals with overweight than in individuals with normal weight when changes were of marginal interest, suggesting a stronger avoidance of the food-related picture. This study showed that food-related stimuli influence attention allocation processes in both participants with overweight and normal weight. In particular, as compared to individuals with normal weight, those with overweight seem to be characterised by a stronger attentional avoidance of (or smaller attention maintenance on) food-related stimuli that could be considered as a voluntary strategy to resist food consumption.

A new approach to facilitating attentional disengagement from food cues in unsuccessful dieters: The bouncing image training task

This study tested the capacity of a modified Bouncing Image Training Task (BITT) to enhance unsuccessful dieters' attentional disengagement from food cues. Unsuccessful dieters were assigned to a training group performing daily BITT sessions for one week (n = 57) or a waitlist control group (n = 56). Change in attention was assessed using a visual search task and an odd-one-out task. Impact of the BITT on food craving and food intake were also assessed. Participants in the training group, compared to waitlist controls, showed reduced attention to food cues from pre-to post-training. Moreover, the reduction in AB to food cues exhibited by those who completed the BITT reflected the relative facilitation of attentional disengagement from food cues, rather than a reduction in attention engagement with food cues. The groups did not differ on food craving or intake post-training. It is concluded that the BITT is a promising procedure for directly manipulating individuals' attentional disengagement from food cues, though its capacity to enhance dieting success has not yet been established.

Exploring preferences for variable delays over fixed delays to high-value food rewards as a model of food-seeking behaviours in humans

Foraging and operant models suggest that animals will tolerate uncertainty or risk to obtain food quickly. In modern food environments, sustained access to quick energy-dense foods can promote weight gain. Here, we used a discrete-choice procedure to examine peoples' decisions about when next to eat high-value, palatable food rewards, probabilistically delivered immediately or following longer delays. In Experiment 1, moderately hungry young females showed consistent preferences for a variable delay option that delivered food rewards immediately or following long delays over a fixed delay option that delivered the same rewards following intermediate delays. These preferences were stronger in females with higher BMIs compared with lower BMIs, suggesting that quick food can enhance the value of uncertain or 'risky' food-seeking strategies in individuals vulnerable to future weight gain. In Experiment 2, prior exposure to a subtle and not easily identifiable food aroma increased selections of the variable delay option following delayed food rewards in a mixed sample of male and female adults, providing preliminary evidence that food cues can sustain uncertain food-seeking strategies. These data highlight a working hypothesis that the rapid delivery and consumption of food rewards, and food cues, can increase risk-tolerance in the food-seeking behaviours of individuals who are vulnerable to weight gain. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Food Cue Reactivity and the Brain-Heart Axis During Cognitive Stress Following Clinically Relevant Weight Loss

Successful weight loss maintainers are more vulnerable to stress induced eating. The aim of our study was to determine what effect an attention-demanding cognitive performance task had on brain-heart reactivity to visual food cues in women who maintained clinically relevant weight loss vs. women who had never weight cycled. A clinical weight loss group (CWL, n = 17) and a BMI-matched control group (CTL, n = 23) completed modified Stroop tasks that either included high calorie food pictures (Food Stroop) or excluded food cues (Office Stroop). ECG, breathing rate, and EEG were recorded. CWL participants: The Eating Restraint scores (Three Factor Eating Questionnaire) of the CWL participants correlated negatively with their heart rates recorded during the Food Stroop task (r = 0.62, p < 0.01). There was no such relationship in CTL participants. The P200 latencies in CWL participants evoked by the Stroop color-word cues at the C3 electrode were positively correlated to the log high frequency power in their cardiac spectrograms during the Food Stroop (r = 0.63, p < 0.02). There were no such relationships in the Office Stroop task nor in CTL participants. Combined Groups: Participants' heart rates were significantly lower (p < 0.05) and their RMSSD values and the log Total Power in their cardiac spectrograms were significantly greater during the Food Stroop vs. Office Stroop (p < 0.01, Bonferroni corrected). In conclusion Eating Restraint scores in CWL participants correlated with their Stroop heart rates, while the P200 latencies evoked by the Stroop cues correlated with the log high frequency power in their cardiac spectrograms (marker of cardiac vagal activation) during the Food Stroop task. This provides evidence that even 12 months after successful weight loss maintenance the cardiac ANS reactivity to food cues while completing a cognitive performance test was still different to that in individuals of normal weight who never weight cycled. Across all participants the cardiac ANS reactivity evoked by performing the Stroop task was lowered by food cues suggesting that the dampening effect of food cues on cardiac ANS reactivity may be one of the drivers of ‘stress induced' eating.

Top-down guidance of attention to food cues is enhanced in individuals with overweight/obesity and predicts change in weight at one-year follow up

Background

Changing eating behaviour may be challenging for individuals with obesity and this may be related to attentional bias towards food. Previous paradigms used to assess attentional bias to food stimuli have not distinguished between bottom-up processes related to assessment of rewarding stimuli versus top-down processes related to effects of mind-set on attention. We investigated whether attentional bias for food cues varies between individuals with overweight/obesity and healthy weight individuals, due to differential top-down control of attention. We also determined whether top-down biases predict food consumption in the lab and weight change in our sample over one-year.

Methods

Forty-three participants with overweight/obesity and 49 healthy weight participants between the ages of 18 and 58 participated. Participants completed two attention tasks in a counterbalanced order: (i) a priming task assessing bottom-up control of attention and (ii) a working memory task assessing top-down control of attention. Eating behaviour was assessed by a taste test. At one-year follow-up participants returned to the laboratory to assess changes in their body mass index (BMI).

Results

The healthy weight and overweight/obese groups did not differ in demographics and baseline measures (appetite, food liking, taste test food intake). Participants with overweight/obesity showed greater top-down attentional bias towards food cues than did healthy weight participants but had no difference in bottom-up attentional bias. Top down attentional bias towards food cues predicted weight change over one-year but did not predict food intake in the taste test.

Conclusions

The present findings illustrate that the relationship between attentional bias for food, food intake, and body weight is complex. Top-down effects of mind-set on attention, rather than bottom-up control of attention to food may contribute to patterns of eating that result in development and/or maintenance of overweight/obesity. Interventions targeted at top down biases could be effective in facilitating prevention of weight gain.

5-a-day fruit and vegetable food product labels: reduced fruit and vegetable consumption following an exaggerated compared to a modest label

BACKGROUND

Food product labels based on the WHO 5-a-day fruit and vegetable (FV) message are becoming increasingly common, but these labels may impact negatively on complementary or subsequent FV consumption. This study aimed to investigate the impact of a '3 of your 5-a-day' versus a '1 of your 5-a-day' smoothie product label on subsequent FV consumption.

METHODS

Using an acute experimental design, 194 participants (90 males, 104 females) were randomised to consume a smoothie labelled as either '3 of your 5-a-day' (N = 97) or '1 of your 5-a-day' (N = 97) in full, following a usual breakfast. Subsequent FV consumption was measured for the rest of the day using 24-h recall. Usual FV consumption was also assessed via 24-h recall for the day before the study.

RESULTS

Regression analyses revealed a significantly lower subsequent FV consumption following smoothies displaying the '3 of your 5-a-day' label compared to the '1 of your 5-a-day' label (Beta = - 0.15, p = 0.04). Secondary analyses revealed these effects to be driven mainly by changes to consumption in usual high FV consumers, in females and in vegetable as opposed to fruit consumption.

CONCLUSIONS

These findings demonstrate a role for label information in food intake, and the potential negative impacts of an exaggerated food product label on healthy food consumption and healthy dietary profiles.

The effect of attentional bias modification training on food intake in overweight and obese women

This study modified food attentional biases via computerized attentional bias modification training and examined the effects on food intake. Overweight women were randomly allocated to (1) direct attention away from food (“attentional-training”), (2) direct attention at random to food or neutral (“placebo”), or (3) no training (“control”). Individuals then completed a taste test. Those in the attentional-training consumed on average 600 kJ less of total food compared to the placebo. Those in the attentional-training had a reduction in food attentional bias compared to the placebo group, when controlling for executive function. Attentional-training seems to reduce high-calorie intake in overweight women.

The effect of combined avoidance and control training on implicit food evaluation and choice

BACKGROUND

Continual exposure to food cues in the environment contributes to unhealthy eating behaviour. According to dual-process models, such behaviour is partly determined by automatic processing of unhealthy food cues (e.g., approach bias), which fails to be regulated by controlled processing (e.g., inhibitory control). The current study aimed to investigate the effect of combined avoidance and control training on implicit evaluation (liking), choice, and consumption of unhealthy snack food.

METHOD

Participants were 240 undergraduate women who were randomly allocated to one of four experimental conditions of a 2 (avoidance training: training versus control) x 2 (control training: training versus control) between-subjects design.

RESULTS

The combined training group had a more negative implicit evaluation of unhealthy food than either of the two training conditions alone or the control condition. In addition, participants trained to avoid unhealthy food cues subsequently made fewer unhealthy snack food choices. No significant group differences were found for food intake.

LIMITATIONS

Participants were women generally of a healthy weight. Overweight or obese individuals may derive greater benefit from combined training.

CONCLUSIONS

Results lend support to the theoretical predictions of dual-process models, as the combined training reduced implicit liking of unhealthy food. At a practical level, the findings have implications for the effectiveness of interventions targeting unhealthy eating behaviour.

Tempting foods and the affordability axiom: Food cues change beliefs about the costs of healthy eating

Many consumers report that healthy eating is more expensive than unhealthy eating (the affordability axiom). We hypothesize that endorsement of this belief may be driven by the motivation to eat unhealthy foods. We tested this hypothesis in three studies. Study 1 revealed that the affordability axiom is associated with poorer eating habits and higher Body Mass Index (BMI). Study 2 found that the presence of a tasty food cue in the environment increased endorsement of affordability axiom. Study 3 found that these effects were moderated by one's food intake goals. Food cues led non-dieters to increase endorsement of the affordability axiom, but had the opposite effect among those seeking to restrict their calorie intake. The affordability axiom might persist as a means of validating unhealthy food choices.

Motivational state, reward value, and Pavlovian cues differentially affect skilled forelimb grasping in rats

Motor skills represent high-precision movements performed at optimal speed and accuracy. Such motor skills are learned with practice over time. Besides practice, effects of motivation have also been shown to influence speed and accuracy of movements, suggesting that fast movements are performed to maximize gained reward over time as noted in previous studies. In rodents, skilled motor performance has been successfully modeled with the skilled grasping task, in which animals use their forepaw to grasp for sugar pellet rewards through a narrow window. Using sugar pellets, the skilled grasping task is inherently tied to motivation processes. In the present study, we performed three experiments modulating animals’ motivation during skilled grasping by changing the motivational state, presenting different reward value ratios, and displaying Pavlovian stimuli. We found in all three studies that motivation affected the speed of skilled grasping movements, with the strongest effects seen due to motivational state and reward value. Furthermore, accuracy of the movement, measured in success rate, showed a strong dependence on motivational state as well. Pavlovian cues had only minor effects on skilled grasping, but results indicate an inverse Pavlovian-instrumental transfer effect on movement speed. These findings have broad implications considering the increasing use of skilled grasping in studies of motor system structure, function, and recovery after injuries.

Cognitive processing of food rewards

Cues associated with tasty foods, such as their smell or taste, are strong motivators of eating, but the power of food cues on behaviour varies from moment to moment and from person to person. Variation in the rewarding value of a food with metabolic state explains why food cues are more attractive when hungry. However, cognitive processes are also important determinants of our responses to food cues. An urge to consume a tempting food may be resisted if, for example, a person has a longer term goal of weight loss. There is also evidence that responses to food cues can be facilitated or inhibited by memory processes. The aim of this review is to add to the literature on cognitive control of eating by reviewing recent evidence on the influence of working memory and episodic memory processes on responses to food cues. It is argued that processing of food information in working memory affects how much attention is paid to food cues in the environment and promotes the motivation to seek out food in the absence of direct contact with food cues. It is further argued that memories of specific recent eating episodes play an important role in directing food choices and influencing when and how much we eat. However, these memory processes are prone to disruption. When this happens, eating behaviour may become more cue-driven and less flexible. In the modern food environment, disruption of cognitive processing of food reward cues may lead to overconsumption and obesity.

Episodic sucrose intake during food restriction increases synaptic abundance of AMPA receptors in nucleus accumbens and augments intake of sucrose following restoration of ad libitum feeding

Weight-loss dieting often leads to loss of control, rebound weight gain, and is a risk factor for binge pathology. Based on findings that food restriction (FR) upregulates sucrose-induced trafficking of glutamatergic AMPA receptors to the nucleus accumbens (NAc) postsynaptic density (PSD), this study was an initial test of the hypothesis that episodic "breakthrough" intake of forbidden food during dieting interacts with upregulated mechanisms of synaptic plasticity to increase reward-driven feeding. Ad libitum (AL) fed and FR subjects consumed a limited amount of 10% sucrose, or had access to water, every other day for 10 occasions. Beginning three weeks after return of FR rats to AL feeding, when 24-h chow intake and rate of body weight gain had normalized, subjects with a history of sucrose intake during FR consumed more sucrose during a four week intermittent access protocol than the two AL groups and the group that had access to water during FR. In an experiment that substituted noncontingent administration of d-amphetamine for sucrose, FR subjects displayed an enhanced locomotor response during active FR but a blunted response, relative to AL subjects, during recovery from FR. This result suggests that the enduring increase in sucrose consumption is unlikely to be explained by residual enhancing effects of FR on dopamine signaling. In a biochemical experiment which paralleled the sucrose behavioral experiment, rats with a history of sucrose intake during FR displayed increased abundance of pSer845-GluA1, GluA2, and GluA3 in the NAc PSD relative to rats with a history of FR without sucrose access and rats that had been AL throughout, whether they had a history of episodic sucrose intake or not. A history of FR, with or without a history of sucrose intake, was associated with increased abundance of GluA1. A terminal 15-min bout of sucrose intake produced a further increase in pSer845-GluA1 and GluA2 in subjects with a history of sucrose intake during FR. Generally, neither a history of sucrose intake nor a terminal bout of sucrose intake affected AMPA receptor abundance in the NAc PSD of AL subjects. Together, these results are consistent with the hypothesis, but the functional contribution of increased synaptic incorporation of AMPA receptors remains to be established.

Implication of corticotropic hormone axis in eating behaviour pattern in obese and type 2 diabetic participants

In Algeria, eating behaviour has been increasingly deviated from its traditional Mediterranean diet to modern fast food style. The present study examines the interactions between eating behaviour pattern (EBP), corticotropic hormone axis and the metabolic syndrome. Our Algerian population cohort comprised of 410 participants (130 obese, 170 type 2 diabetics and 110 healthy participants). The EBP was evaluated by the Three-Factor Eating Questionnaire test. The anthropometric and metabolic parameters (glucose, TAG, HDL, LDL and cholesterol) and the concentrations of hormones (insulin, adrenocorticotropin hormone (ACTH), cortisol and growth hormone) were determined by biometrics, spectrophotometry and RIA, respectively. Multivariate analyses showed a high correlation between the EBP and the metabolic syndrome, particularly between insulin-resistant state and hypertrophy of visceral adipose tissue. Compared with healthy participants, obese ones showed the hyperphagic type of EBP, i.e. disinhibition and hunger disorders. Conversely, the diabetics showed both the hypophagic and hyperphagic type of EBP. In diabetic and obese participants, cortisol and ACTH secretions were significantly altered, leading to metabolic disorders. The present study confirms the role of EBP in obesity and diabetes.

Increased palatable food intake and response to food cues in intrauterine growth-restricted rats are related to tyrosine hydroxylase content in the orbitofrontal cortex and nucleus accumbens

Intrauterine growth restriction (IUGR) is associated with altered food preferences, which may contribute to increased risk of obesity. We evaluated the effects of IUGR on attention to a palatable food cue, as well as tyrosine hydroxylase (TH) content in the orbitofrontal cortex (OFC) and nucleus accumbens (NAcc) in response to sweet food intake. From day 10 of gestation and through lactation, Sprague-Dawley rats received either an ad libitum (Adlib) or a 50% food-restricted (FR) diet. At birth, pups were cross-fostered, generating four groups (gestation/lactation): Adlib/Adlib (control), FR/Adlib (intrauterine growth-restricted), Adlib/FR, and FR/FR. Adult attention to palatable food cues was measured using the Attentional Set-Shifting Task (ASST), which uses a sweet pellet as reward. TH content in the OFC and NAcc was measured at baseline and in response to palatable food intake. At 90 days of age, FR/Adlib males ate more sweet food than controls, without differences in females. However, when compared to Controls, FR/Adlib females needed fewer trials to reach criterion in the ASST (p=0.04) and exhibited increased TH content in the OFC in response to sweet food (p=0.03). In the NAcc, there was a differential response of TH content after sweet food intake in both FR/Adlib males and females (p<0.05). Fetal programming of adult food preferences involves the central response to palatable food cues and intake, affecting dopamine release in select structures of the brain reward system.

Attentional bias to food-related visual cues: is there a role in obesity?

The incentive sensitisation model of obesity suggests that modification of the dopaminergic associated reward systems in the brain may result in increased awareness of food-related visual cues present in the current food environment. Having a heightened awareness of these visual food cues may impact on food choices and eating behaviours with those being most aware of or demonstrating greater attention to food-related stimuli potentially being at greater risk of overeating and subsequent weight gain. To date, research related to attentional responses to visual food cues has been both limited and conflicting. Such inconsistent findings may in part be explained by the use of different methodological approaches to measure attentional bias and the impact of other factors such as hunger levels, energy density of visual food cues and individual eating style traits that may influence visual attention to food-related cues outside of weight status alone. This review examines the various methodologies employed to measure attentional bias with a particular focus on the role that attentional processing of food-related visual cues may have in obesity. Based on the findings of this review, it appears that it may be too early to clarify the role visual attention to food-related cues may have in obesity. Results however highlight the importance of considering the most appropriate methodology to use when measuring attentional bias and the characteristics of the study populations targeted while interpreting results to date and in designing future studies.

Sensory-specific appetite is affected by actively smelled food odors and remains stable over time in normal-weight women

Understanding overconsumption starts with knowledge of how separate factors influence our eating behavior. Food cues such as food odors are known for their effect on general appetite and sensory-specific appetite (SSA). Active sniffing rather than passive exposure may induce satiation over time. The objective of this study was to investigate how actively sniffing banana odors affects general appetite, SSA, and subsequent food intake. In a crossover study, 61 women actively smelled cups containing natural banana, artificial banana odor, or water (no odor) for 10 min. Treatment order was randomly assigned as much as possible. General appetite and SSA were monitored by using 100-mm visual analog scales during the 10 min of active sniffing, followed by ad libitum intake of banana milkshake. Results showed that SSA was consistently high (+12 mm) during actively sniffing natural or artificial banana odors, with no decrease in SSA over time. Sniffing both banana odors increased the appetite for banana (+11 mm) and other sweet products (+4 mm), whereas the appetite for savory products decreased by 7 mm (all P < 0.01) compared with no odor. Actively sniffing banana odor did not significantly influence food intake (P = 0.68) or general appetite scores (P = 0.06). In conclusion, SSA scores during active sniffing were identical to the SSA found in a similar study that used passive smelling, suggesting that SSA is independent of the manner of sniffing and exposure time. Moreover, sweet/savory categorization may suggest that food odors communicate information about the nutrient composition of their associated foods. These data clearly show the appetizing effects of food odors.

Attentional bias modification encourages healthy eating

The continual exposure to unhealthy food cues in the environment encourages poor dietary habits, in particular consuming too much fat and sugar, and not enough fruit and vegetables. According to Berridge's (2009) model of food reward, unhealthy eating is a behavioural response to biased attentional processing. The present study used an established attentional bias modification paradigm to discourage the consumption of unhealthy food and instead promote healthy eating. Participants were 146 undergraduate women who were randomly assigned to two groups: one was trained to direct their attention toward pictures of healthy food ('attend healthy' group) and the other toward unhealthy food ('attend unhealthy' group). It was found that participants trained to attend to healthy food cues demonstrated an increased attentional bias for such cues and ate relatively more of the healthy than unhealthy snacks compared to the 'attend unhealthy' group. Theoretically, the results support the postulated link between biased attentional processing and consumption (Berridge, 2009). At a practical level, they offer potential scope for interventions that focus on eating well.

Using virtual reality to study food cravings

Food cravings (FCs) are associated with overeating and obesity and are triggered by environmental cues. The study of FCs is challenged by difficulty replicating the natural environment in a laboratory. Virtual reality (VR) could be used to deliver naturalistic cues in a laboratory. The purpose of this study was to investigate whether food related cues delivered by VR could induce greater FCs than neutral VR cues, photographic food cues, or real food. Sixty normal weight non-dieting women were recruited; and, to prevent a floor effect, half were primed with a monotonous diet (MD). Experimental procedures involved delivering neutral cues via VR and food related cues via VR, photographs, and real food in counterbalanced order while measuring subjective (self-report) and objective (salivation) FCs. FCs produced by VR were marginally greater than a neutral cue, not significantly different from picture cues, and significantly less than real food. The modest effects may have been due to quality of the VR system and/or measures of FC (i.e., self-report and salivation). FC threshold among non-dieting normal weight women was lowered with the use of a MD condition. Weight loss programs with monotonous diets may inadvertently increase FCs making diet compliance more difficult.

Sweetened drink and snacking cues in adolescents: a study using ecological momentary assessment

The objective of this study was to identify physical, social, and intrapersonal cues that were associated with the consumption of sweetened beverages and sweet and salty snacks among adolescents from lower SES neighborhoods. Students were recruited from high schools with a minimum level of 25% free or reduced cost lunches. Using ecological momentary assessment, participants (N=158) were trained to answer brief questionnaires on handheld PDA devices: (a) each time they ate or drank, (b) when prompted randomly, and (c) once each evening. Data were collected over 7days for each participant. Participants reported their location (e.g., school grounds, home), mood, social environment, activities (e.g., watching TV, texting), cravings, food cues (e.g., saw a snack), and food choices. Results showed that having unhealthy snacks or sweet drinks among adolescents was associated with being at school, being with friends, feeling lonely or bored, craving a drink or snack, and being exposed to food cues. Surprisingly, sweet drink consumption was associated with exercising. Watching TV was associated with consuming sweet snacks but not with salty snacks or sweet drinks. These findings identify important environmental and intrapersonal cues to poor snacking choices that may be applied to interventions designed to disrupt these food-related, cue-behavior linked habits.

Links between ruminants' food preference and their welfare

Nutrition is an important aspect of welfare, and in most recommendations for the welfare of animals adequate nutrition is a primary requirement. However, in intensive livestock production systems the decision for adequate nutrition is made based on traditional paradigms of feeding monotonous rations or plant monocultures, frequently with excesses or imbalances of nutrients relative to the individuals' physiology, which can compromise welfare. Individual ruminants can better meet their needs for nutrients and regulate their intake of secondary compounds when offered a variety of foods than when constrained to a single food, even if the food is nutritionally balanced. The concept of food variety is central because monotonous flavors and feeds and excess nutrients all cause animals to satiate, which in turn causes animals to eat a variety of foods. When offered a variety of foods, satiety for single foods stimulates the selection of a diverse diet and thus food intake, but when restricted to a monotonous diet satiety is aversive and limits food intake. Moreover, if a monotonous diet is aversive to animals then this could be stressful, even if monotony implies consuming a balanced diet. A diverse diet may also increase resistance to disease in ruminants, by allowing consumption of small amounts of compounds with antimicrobial/antiparasitic effects and immunity-enhancing properties. Herbivores also experience the benefits of ingesting compounds with medicinal (i.e. antiparasitic) benefits and they learn to prefer foods containing such compounds as their preferences are associatively conditioned by the food's homeostatic utility to the body. Such learned patterns of behavior begin in utero and feeding experiences early in life cause changes - neurological, morphological and physiological - in animals, which influence on their subsequent behavior and welfare. Such experiences with the environment enable animals to adapt to local diets and stressors and reduce the levels of fear. Finally, feeding behavior in farm animals could be an aid in the early detection and mitigation of pain or sickness, and as such become an important tool in the identification of welfare and health of animals before the appearance of clinical signs. Management strategies in ruminant production systems could benefit by allowing animals to manifest their feeding preferences, thereby acknowledging the animals' role as active players in feeding systems, instead of regarding them as passive entities that just respond to prescriptions and formulations.

The power of social influence over food intake: examining the effects of attentional bias and impulsivity

Numerous studies have shown that people adjust their intake directly to that of their eating companions. A potential explanation for this modelling effect is that the eating behaviour of others operates as an external eating cue that stimulates food intake. The present study explored whether this cue-reactive mechanism can account for modelling effects on intake. It was investigated whether attentional bias towards dynamic eating cues and impulsivity would influence the degree of modelling. Participants completed one individual session and one session in which an experimental confederate accompanied them. In the first session, eye movements were recorded as an index of attentional bias to dynamic eating cues. In addition, self-reported impulsivity and response inhibition were assessed. The second session employed a between-participants design with three experimental conditions in which participants were exposed to a same-sex confederate instructed to eat nothing, a low or a large amount of M&Ms. A total of eighty-five young women participated. The participants' self-reported impulsivity determined the occurrence of modelling; only low-impulsive women adjusted their intake to that of their eating companion. Attention towards eating cues and response inhibition, however, did not moderate modelling of food intake. The present study suggests that cue-reactive mechanisms may not underlie modelling of food intake. Instead, the results emphasise the importance of social norms in explaining modelling effects, whereas it is suggested that the degree of impulsivity may play a role in whether or not women adhere to the intake norms set by their eating companion.

Functional brain imaging of appetite

Obesity is a neurobehavioral disorder that results from a combination of overeating and insufficient physical activity. Finely tuned mechanisms exist to match food intake to caloric expenditure. However, faced with abundant inexpensive and calorie-dense foods, many humans (and perhaps most) have a tendency to consume beyond their caloric needs. The brain controls food intake by sensing internal energy-balance signals and external cues of food availability, and by controlling feeding behavior; it is therefore at the centre of the obesity problem. This article reviews the recent use of functional brain imaging in humans to study the neural control of appetite, and how the neural systems involved may cause vulnerability to overeating in the obesogenic environment.

Top down modulation of attention to food cues via working memory

Attentional biases towards food cues may be linked to the development of obesity. The present study investigated the mechanisms underlying attentional biases to food cues by assessing the role of top down influences, such as working memory (WM). We assessed whether attention in normal-weight, sated participants was drawn to food items specifically when that food item was held in WM. Twenty-three participants (15 f/8 m, age 23.4±5 year, BMI 23.5±4 kg/m(2)) took part in a laboratory based study assessing reaction times to food and non-food stimuli. Participants were presented with an initial cue stimulus to either hold in WM or to merely attend to, and then searched for the target (a circle) in a two-item display. On valid trials the target was flanked by a picture matching the cue, on neutral trials the display did not contain a picture matching the cue, and on invalid trials the distractor (a square) was flanked by a picture matching the cue. Cues were food, cars or stationery items. We observed that, relative to the effects with non-food stimuli, food items in WM strongly affected attention when the memorised cue re-appeared in the search display. In particular there was an enhanced response on valid trials, when the re-appearance of the memorised cue coincided with the search target. There were no effects of cue category on attentional guidance when the cues were merely attended to but not held in WM. These data point towards food having a strong effect on top-down guidance of search from working memory, and suggest a mechanism whereby individuals who are preoccupied with thoughts of food, for example obese individuals, show facilitated detection of food cues in the environment.

Food and drug cues activate similar brain regions: a meta-analysis of functional MRI studies

In healthy individuals, food cues can trigger hunger and feeding behavior. Likewise, smoking cues can trigger craving and relapse in smokers. Brain imaging studies report that structures involved in appetitive behaviors and reward, notably the insula, striatum, amygdala and orbital frontal cortex, tend to be activated by both visual food and smoking cues. Here, by carrying out a meta-analysis of human neuro-imaging studies, we investigate the neural network activated by: 1) food versus neutral cues (14 studies, 142 foci) 2) smoking versus neutral cues (15 studies, 176 foci) 3) smoking versus neutral cues when correlated with craving scores (7 studies, 108 foci). PubMed was used to identify cue-reactivity imaging studies that compared brain response to visual food or smoking cues to neutral cues. Fourteen articles were identified for the food meta-analysis and fifteen articles were identified for the smoking meta-analysis. Six articles were identified for the smoking cue correlated with craving analysis. Meta-analyses were carried out using activation likelihood estimation. Food cues were associated with increased blood oxygen level dependent (BOLD) response in the left amygdala, bilateral insula, bilateral orbital frontal cortex, and striatum. Smoking cues were associated with increased BOLD signal in the same areas, with the exception of the insula. However, the smoking meta-analysis of brain maps correlating cue-reactivity with subjective craving did identify the insula, suggesting that insula activation is only found when craving levels are high. The brain areas identified here are involved in learning, memory and motivation, and their cue-induced activity is an index of the incentive salience of the cues. Using meta-analytic techniques to combine a series of studies, we found that food and smoking cues activate comparable brain networks. There is significant overlap in brain regions responding to conditioned cues associated with natural and drug rewards.

Food scarcity, neuroadaptations, and the pathogenic potential of dieting in an unnatural ecology: binge eating and drug abuse

In the laboratory, food restriction has been shown to induce neuroadaptations in brain reward circuitry which are likely to be among those that facilitate survival during periods of food scarcity in the wild. However, the upregulation of mechanisms that promote foraging and reward-related learning may pose a hazard when food restriction is self-imposed in an ecology of abundant appetitive rewards. For example, episodes of loss of control during weight-loss dieting, use of drugs with addictive potential as diet aids, and alternating fasting with alcohol consumption in order to avoid weight gain, may induce synaptic plasticity that increases the risk of enduring maladaptive reward-directed behavior. In the present mini-review, representative basic research findings are outlined which indicate that food restriction alters the function of mesoaccumbens dopamine neurons, potentiates cellular and behavioral responses to D-1 and D-2 dopamine receptor stimulation, and increases stimulus-induced synaptic insertion of AMPA receptors in nucleus accumbens. Possible mechanistic underpinnings of increased drug reward magnitude, drug-seeking, and binge intake of sucrose in food-restricted animal subjects are discussed and possible implications for human weight-loss dieting are considered.

The effects of transient starvation persist through direct interactions between CaMKII and ether-a-go-go K+ channels in C. elegans males

Prolonged nutrient limitation has been extensively studied due to its positive effects on life span. However, less is understood of how brief periods of starvation can have lasting consequences. In this study, we used genetics, biochemistry, pharmacology and behavioral analysis to show that after a limited period of starvation, the synthesis of egl-2-encoded ether-a-go-go (EAG) K+ channels and its C-terminal modifications by unc-43-encoded CaMKII have a perduring effect on C. elegans male sexual behavior. EGL-2 and UNC-43 interactions, induced after food deprivation, maintain reduced excitability in muscles involved in sex. In young adult males, spastic contractions occur in cholinergic-activated sex muscles that lack functional unc-103-encoded ERG-like K+ channels. Promoting EGL-2 and UNC-43 interactions in unc-103 mutant adult males by starving them for a few hours reduce spastic muscle contractions over multiple days. Although transient starvation during early adulthood has a hormetic effect of suppressing mutation-induced muscle contractions, the treatment reduces the ability of young wild-type (WT) males to compete with well-fed cohorts in siring progeny.