The body asks and the mind judges: Food cravings in eating disorders

Habituation or sensitization of brain response to food cues: Temporal dynamic analysis in an functional magnetic resonance imaging study

Introduction

In the modern obesogenic environment, heightened reactivity to food-associated cues plays a major role in overconsumption by evoking appetitive responses. Accordingly, functional magnetic resonance imaging (fMRI) studies have implicated regions of the salience and rewards processing in this dysfunctional food cue-reactivity, but the temporal dynamics of brain activation (sensitization or habituation over time) remain poorly understood.

Methods

Forty-nine obese or overweight adults were scanned in a single fMRI session to examine brain activation during the performance of a food cue-reactivity task. A general linear model (GLM) was used to validate the activation pattern of food cue reactivity in food > neutral contrast. The linear mixed effect models were used to examine the effect of time on the neuronal response during the paradigm of food cue reactivity. Neuro-behavioral relationships were investigated with Pearson's correlation tests and group factor analysis (GFA).

Results

A linear mixed-effect model revealed a trend for the time-by-condition interactions in the left medial amygdala [t(289) = 2.21, β = 0.1, P = 0.028], right lateral amygdala [t(289) = 2.01, β = 0.26, P = 0.045], right nucleus accumbens (NAc) [t(289) = 2.81, β = 0.13, P = 0.005] and left dorsolateral prefrontal cortex (DLPFC) [t(289) = 2.58, β = 0.14, P = 0.01], as well as in the left superior temporal cortex [42 Area: t(289) = 2.53, β = 0.15, P = 0.012; TE1.0_TE1.2 Area: t(289) = 3.13, β = 0.27, P = 0.002]. Habituation of blood-oxygenation-level-dependent (BOLD) signal during exposure to food vs. neutral stimuli was evident in these regions. We have not found any area in the brain with significant increased response to food-related cues over time (sensitization). Our results elucidate the temporal dynamics of cue-reactivity in overweight and obese individuals with food-induced craving. Both subcortical areas involved in reward processing and cortical areas involved in inhibitory processing are getting habituated over time in response to food vs. neutral cues. There were significant bivariate correlations between self-report behavioral/psychological measures with individual habituation slopes for the regions with dynamic activity, but no robust cross-unit latent factors were identified between the behavioral, demographic, and self-report psychological groups.

Discussion

This work provides novel insights into dynamic neural circuit mechanisms supporting food cue reactivity, thereby suggesting pathways in biomarker development and cue-desensitization interventions.

Craving for carbs: food craving and disordered eating in low-carb dieters and its association with intermittent fasting

Studies point to positive outcomes in a diet with reduction of carbohydrates and that the associated practice of intermittent fasting (IF) might increase weight loss. Although dieting might be related to disordered eating, little evidence is available about the role of restrictive carbohydrates diets on disordered eating. This study aimed to explore if doing low-carb (LC) diets was related to disordered eating and if IF would increase these symptoms. The sample comprised university students (n = 682), with a mean age of 22 years old and average BMI of 23.6 kg/m2 (SD = 4.3). Twenty-seven percent (n = 188) of respondents reported doing LC diet in the last three months. Of those, 31% (n = 58) reported doing LC diet combined with periods of IF. Mean scores were compared using parametric tests, and effects size and correlations between variables were calculated. Dieters showed higher levels of binge eating, food cravings, cognitive restraint, cognitive restraint toward carbohydrates when compared to non-dieters. The association of LC and IF was related to an increase in disordered eating, especially binge eating and food cravings, specifically 'Lack of control', 'Thoughts or preoccupation with food,' and 'Guilt from cravings and/or for giving in to them'. These results provide evidence that restrictive carbohydrate diets and IF may increase cognitive restraint and, consequently, food cravings.Level III: Evidence obtained from cohort or case-control analytic studies.

The body asks and the mind judges: the episode of food craving, its triggers and nutritional treatment

Food desires are defined as motivations that drive the search for and consumption of food. However, when domains of intensity and urgency are activated, these desires can become intense (i.e. food craving), being then characterized by episodes or cognitive events loaded with affectivity, in which food is associated with obtaining pleasure or relief, which is the only attentional focus. Specificity and urgency mark the differentiation between food desires and cravings. The process of elaboration with vivid images, the retention in working memory, the emergence of a negative affect state (awareness of the lack), and a committed attentional focus to seek food are characterized as stages of an episode of food craving. Individuals with eating disorders have the lowest levels of food craving when it comes to anorexia nervosa and the subsequent increase to bulimia nervosa and binge eating disorder. Some environmental and cultural triggers and internal factors of cognition and emotions play a crucial role in the emergence of food craving episodes. The external factors include positive/negative events, food environment, advertisements, cultural beliefs about food, specific locations, and food itself. The internal factors comprise dietary restriction, food reward, impulsivity/inflexibility, emotions, thoughts and feelings about food, hunger/satiety/appetite, and anxious/depressive symptoms. Treatment involves the association of flexibility, awareness, and questioning strategies about dietary practices based on three principles: unconditional permission to eat, eating more for physical than emotional reasons, and tuning in with the body’s signs of hunger and satiety (intuitive eating).

Food-Specific Inhibition Training for Food Devaluation: A Meta-Analysis

Theories have suggested that food-specific inhibition training could lead to food devaluation which, in turn, may help people to regulate their eating behavior. In this review, we have synthesized the current literature on this topic by conducting a meta-analysis of studies investigating the effects of food-specific inhibition training on food evaluation. We identified 24 studies-with 36 independent samples, 77 effect sizes, and 3032 participants-that met our inclusion criteria. Effect sizes were analyzed using the robust variance estimation in random effects meta-regression technique. The results indicate that food-specific inhibition training can lead to statistically significant reductions in food evaluation. More specifically, it was observed that the effects of training on participants' food evaluation differed according to the type of evaluation; food-specific inhibition training significantly decreased participants' explicit food evaluation, but not their implicit food evaluation. However, because most of the included studies focused on trained food items and short-term outcomes in normal-weight samples, more research is needed on the continuance of the training effects, as well as on the extent to which effects can be generalized to untrained food items or different populations (e.g., overweight or obese individuals).

Differences in Food Craving in Individuals With Obesity With and Without Binge Eating Disorder

Overeating behavior is supposedly a major contributing factor to weight gain and obesity. Binge eating disorder (BED) with reoccurring episodes of excessive overeating is strongly associated with obesity. Learning models of overeating behavior and BED assume that mere confrontation with food leads to a conditioned response that is experienced as food craving. Accordingly, individuals with obesity and BED were shown to have high trait food cravings. To date, little is known about differences in state food cravings and cue reactivity at the sight of palatable food in individuals with obesity and BED compared to individuals with obesity without BED. Therefore, the aim of our study was to examine differences in cue-induced, state and trait food cravings in people with obesity with and without BED. We found that all aspects of food cravings were more prevalent in individuals with obesity and BED than in individuals without BED. By implementing a food cue reactivity paradigm, our results show that individuals with obesity with BED have more cue-induced cravings than individuals with obesity without BED. Moreover, these cue-induced cravings in individuals with obesity and BED were highest for high-fat and high-sugar foods as opposed to low-calorie foods. Thus, our results emphasize the role of increased cue reactivity and craving at the sight of palatable foods in individuals with obesity and BED. Hence, our findings support etiological models of conditioned binge eating and are in line with interventions targeting cue reactivity in BED.

Prevalence and correlates of food addiction: Systematic review of studies with the YFAS 2.0

BACKGROUND

Research on food addiction (FA) has been growing and increasing interest has been seen in comprehending its mechanisms and clinical and psychological correlates of this phenomena. This field of study is specially apply to understand obesity and eating behavior issues related to eating disorders (ED).

OBJECTIVES

We performed a literature review that describe recent research using the updated version of the Yale Food Addiction Scale (YFAS 2.0) or modified-YFAS (mYFAS 2.0), from the date of its publication.

METHODS

Search were performed in Web of Science, Pubmed and PsycNET databases for studies that used the YFAS 2.0 and mYFAS 2.0.

RESULTS

The studies (n = 53) investigated adaptation and validation of the scale in different cultures (n = 13), prevalence on nonclinical populations and representative samples (n = 5), food addiction in obesity samples (n = 11), in samples with ED and disordered eating (n = 10) and studies that investigated FA in association with other clinical and psychological variables (n = 14).

DISCUSSION

Studies with the YFAS 2.0 reveal higher prevalence of FA in different samples, and a great association between FA and BED, BN and obesity. Implications for diagnostic of this phenomena and the overlap between FA and other disorders are discussed.

CONCLUSIONS

The field of FA remains an open subject and effort must be implied to understand the subjective experience of addiction related to eating and food.