How fat will it make me? Estimation of weight gain in anorexia nervosa

Neuroimaging and neuroendocrine insights into food cravings and appetite interventions in obesity

This article reviews the previous studies on the distinction between food cravings and appetite, and how they are regulated by hormones and reflected in brain activity. Based on existing research, food cravings are defined as individual preferences influenced by hormones and psychological factors, which differ from appetite, as they are not necessarily related to hunger or nutritional needs. The article also evaluates the neuroimaging findings about food cravings, and interventions to reduce food cravings, such as mindfulness training, alternative sweeteners, non-invasive brain stimulation techniques, cognitive-behavioral therapy, and imaginal retraining, and points out their advantages, disadvantages, and limitations. Furthermore, the article delves into the potential future directions in the field, emphasizing the need for a neuroendocrine perspective, considerations for associated psychiatric disorders, innovative clinical interventions, and emerging therapeutic frontiers in obesity management. The article outlines the neuro-endocrine basis of food cravings, including ghrelin, leptin, melanocortin, oxytocin, glucagon-like peptide-1, baclofen, and other hormones and their brain regions of action. The article argues that food cravings are an important target for obesity, and more research is needed to explore their complex characteristics and mechanisms, and how to effectively interact with their neuro-endocrine pathways. The article provides a new perspective and approach to the prevention and treatment of obesity.

Visualizing Emotional Arousal within the Context of Body Size Evaluation: A Pilot Study of Steady-State Visual Evoked Potentials in Women with Anorexia Nervosa and Healthy Controls

Maladaptive body size evaluation processes and body dissatisfaction are known as central risk factors for the development and maintenance of anorexia nervosa (AN). This study aimed to experimentally test potential key facets, such as (psycho)physiological, cognitive-verbal and behavioral mechanisms, within the context of these evaluation processes. Twenty-two females with AN (AN-G) and 22 healthy controls (HC-G) looked at pictures of their body gradually increasing in weight using a morphing technique. Implicit emotional arousal was assessed using steady-state visual evoked potentials (SSVEP) in electroencephalography. Additionally, in a forced-choice body size evaluation task, participants were asked to classify pictures of their own body as not big or big while reaction times were captured. A significantly earlier increase in SSVEPs emerged in AN-G compared to HC-G (p <.05), with AN-G evaluating their bodies in the morphing process as big at a significantly thinner body size (p <.05). The AN-G showed faster reaction times in the categorical evaluation of body stimuli (p <.05). Findings from this multimodal paradigm underline the importance of body size evaluation mechanisms and underlying emotional arousal for AN. A differentiated understanding of these processes is essential, since the effectiveness of therapeutic interventions for AN is limited and relapses are frequent.

The revolting body: Self-disgust as a key factor in anorexia nervosa

In this article, we present a theoretical model that points to disgust-induced avoidance as a mechanism that can help explain the persistent and excessive food restriction in individuals with anorexia nervosa (AN). Disgust is characterized by intense negative feelings of revulsion and an overwhelming and irresistible urge to avoid potential disgust elicitors. When eating, or even the prospect of eating, elicits overwhelming feelings of disgust in individuals with AN, this could explain why food restriction persists even when someone is in a state of starvation. Following this model, disgust is elicited by the expected impact of food on the own body ("becoming fat") resulting in body-related self-disgust. We argue that limiting food intake may serve to avoid self-disgust. This implies that when self-disgust remains unchanged after treatment of AN, residual levels of self-disgust after treatment could make individuals vulnerable to relapse.

Prevention of diet restriction induced hyperactivity but not body-weight reduction in rats co-treated with tryptophan: relationship with striatal serotonin and dopamine metabolism and serotonin-1A auto-receptor expression

Anorexia Nervosa (AN) is an eating and behavioral disorder characterized with anxiety/depression, hyperactivity, behavioral impulsivity and psychosis. Most of the associated symptoms are related to the deficiency of serotonin (5-hydroxytryptamine: 5-HT) stores. A deficiency of 5-HT can modulate dopamine neurotransmission in the striatum to elicit hyperactivity and psychosis in AN patients. Also, the release and availability of 5-HT are modulated by serotonin-1A (5-HT1A) auto-receptor. The present study investigates the role of striatal metabolism of 5-HT and dopamine in precipitating hyperactivity in the rat model of diet restriction (DR) induced AN. The role of tryptophan (Trp) in influencing the 5-HT metabolism and the mRNA expression of 5-HT1A auto-receptor is also investigated. We find that long-term DR for 38 days reduces body-weight in rats and produces hyperactivity, similar to AN. This hyperactivity is characterized by declined striatal metabolism of both, dopamine and 5-HT. The mRNA expression of 5-HT1A auto-receptor in the raphe nuclei is also decreased. Trp co-treatment improves these deficiencies in monoamine metabolism and alleviates hyperactivity. Interestingly, DR-induced changes in body-weights are not effected by Trp co-treatment. The study suggests that the striatal metabolism of 5-HT and dopamine and mRNA expression of 5-HT1A auto-receptor has an important role in the pathogenesis of AN. The finding suggests that co-use of Trp can prevent precipitation of AN by normalizing 5-HT metabolism.

How do patients with eating disorders perceive and evaluate food portion sizes? A systematic review

OBJECTIVE

The selection of adequate portion sizes plays a key role in the nutritional treatment of eating disorders (EDs). There is limited knowledge concerning the estimation of portion sizes in individuals with EDs.

METHOD

We performed a systematic review according to the PRISMA statement to synthesise current evidence in this field. Of N = 584 hits, four full-texts were included in the qualitative synthesis.

RESULTS

While patients with anorexia nervosa (AN) tend to overestimate the size of energy-dense food items and small to medium sized meal portions, they do not show a different estimation compared to healthy controls when judging the amount of food pieces. Large portion sizes were associated with increased anxiety in patients with AN.

DISCUSSION

The overestimation of food portion sizes seems to be driven by attitudinal and/or higher cognitive factors associated with AN. Differences between the studies are discussed and suggestions for future studies are given.

Effects of hunger on mood and affect reactivity to monetary reward in women with obesity - A pilot study

Worldwide, nearly 3 million people die every year because of being overweight or obese. Although obesity is a metabolic disease, behavioral aspects are important in its etiology. Hunger changes the rewarding potential of food in normal-weight controls. In obesity, impairments related to reward processing are present, but it is not clear whether these are due to mental disorders more common among this population. Therefore, in this pilot study, we aimed at investigating whether fasting influence mood reactivity to reward in people with obesity. Women with obesity (n = 11, all mentally healthy) and normal weight controls (n = 17) were compared on a computerized monetary reward task (the wheel of fortune), using self-reports of mood and affect (e.g., PANAS and mood evaluation during the task) as dependent variables. This task was done in 2 satiety conditions, during fasting and after eating. Partially, in line with our expectation of a reduced affect and mood reactivity to monetary reward in participants with obesity accentuated by fasting, our results indicated a significant within-group difference across time (before and after the task), with monetary gains significantly improving positive affect in healthy controls (p>0.001), but not in individuals with obesity (p = 0.32). There were no significant between-group differences in positive affect before (p = 0.328) and after (p = 0.70) the task. In addition, women with obesity, compared to controls, reported more negative affect in general (p < 0.05) and less mood reactivity during the task in response to risky gains (p < 0.001) than healthy controls. The latter was independent of the level of satiety. These preliminary results suggest an impairment in mood reactivity to monetary reward in women with obesity which is not connected to the fasting state. Increasing the reinforcing potential of rewards other than food in obesity may be one target of intervention in order to verify if that could reduce overeating.

Body image avoidance affects interpersonal distance perception: A virtual environment experiment

OBJECTIVE

Eating disorders have a considerable influence on social contacts. The avoidance towards the own body may result in the avoidance of others. Previous research has found a preference for larger interaction distances in individuals with eating disorders (ED) as compared to control participants (CG). We aimed to replicate these findings and to investigate whether the body weight of the interactant moderates the effect.

METHOD

We recruited a female sample with mixed ED subtypes (n = 21) and a female CG (n = 28). Participants were immersed in a virtual environment and engaged in a number of fictitious social interactions. They approached a virtual person until a comfortable distance for interaction was reached. The approached virtual persons differed with respect to body weight in five levels (underweight to obese).

RESULTS

Our results indicate that interpersonal distance varies as a U-shaped function of the avatar's body weight, and that higher levels of body avoidance, present in ED individuals, magnify this effect.

CONCLUSIONS

We discuss our results with regard to the role of perspective and disgust to provide a useful framework and to motivate future studies in the domain of body avoidance in social interactions.

A systematic and methodological review of attentional biases in eating disorders: Food, body, and perfectionism

OBJECTIVE

The current systematic and methodological review aimed to critically review existing literature utilizing implicit processing, or automatic approach- and/or avoidance-related attentional biases between eating disorder (ED) and nonclinical samples, which (a) highlights how psychophysiological methods advance knowledge of ED implicit bias; (b) explains how findings fit into transdiagnostic versus disorder-specific ED frameworks; and (c) suggests how research can address perfectionism-related ED biases.

METHOD

Three databases were systematically searched to identify studies: PubMed, Scopus, and PsychInfo electronic databases. Peer-reviewed studies of 18- to 39-year-olds with both clinical ED and healthy samples assessing visual attentional biases using pictorial and/or linguistic stimuli related to food, body, and/or perfectionism were included.

RESULTS

Forty-six studies were included. While behavioral results were often similar across ED diagnoses, studies incorporating psychophysiological measures often revealed disease-specific attentional biases. Specifically, women with bulimia nervosa (BN) tend to approach food and other body types, whereas women with anorexia nervosa (AN) tend to avoid food as well as overweight bodies.

CONCLUSIONS

Further integration of psychophysiological and behavioral methods may identify subtle processing variations in ED, which may guide prevention strategies and interventions, and provide important clinical implications. Few implicit bias studies include male participants, investigate binge-eating disorder, or evaluate perfectionism-relevant stimuli, despite the fact that perfectionism is implicated in models of ED.

What can food-image tasks teach us about anorexia nervosa? A systematic review

A salient feature of anorexia nervosa (AN) is the persistent and severe restriction of food, such that dietary intake is inadequate to maintain a healthy body weight. Experimental tasks and paradigms have used illness-relevant stimuli, namely food images, to study the eating-specific neurocognitive mechanisms that promote food avoidance. This systematic review, completed in accordance with PRISMA guidelines, identified and critically evaluated paradigms involving images of food that have been used to study AN. There were 50 eligible studies, published before March 10th 2018, identified from Medline and PsychINFO searches, and reference screening. Studies using food image-based paradigms were categorised into three methodologic approaches: neuropsychology, neurophysiology, and functional magnetic resonance imaging (fMRI). Paradigms were reviewed with a focus on how well they address phenomena central to AN. Across tasks, differences between individuals with AN and healthy peers have been identified, with the most consistent findings in the area of reward processing. Measuring task performance alongside actual eating behaviour, and using experimental manipulations to probe causality, may advance understanding of the mechanisms of illness in AN.

Double standards in body evaluation? How identifying with a body stimulus influences ratings in women with anorexia nervosa and bulimia nervosa

OBJECTIVE

Women with eating disorders (ED) evaluate their own body more negatively than do women without ED. However, it is unclear whether this negative rating is due to objective bodily features or different standards for one's own body and others' bodies. Therefore, the purpose of this study was to examine whether women with ED apply double standards when rating bodies by disentangling the objective features of one's own body from the feelings of ownership.

METHOD

We presented n = 34 women with anorexia nervosa, n = 31 women with bulimia nervosa, and n = 114 healthy controls with pictures of thin, average-weight, overweight, athletic, and hypermuscular bodies. Identity was manipulated by showing each body once with the participant's own face and once with the face of another woman. Participants were instructed to report their emotional state according to valence and arousal and to rate body attractiveness, body fat, and muscle mass.

RESULTS

Women with anorexia nervosa and bulimia nervosa displayed greater self-deprecating double standards in body fat rating than did women without ED, as quantified by the difference between the ratings of the same body with one's own versus another woman's face. Double standards reflected in valence, arousal and attractiveness ratings were significantly more pronounced in women with anorexia nervosa than in women without ED.

DISCUSSION

The double standards found may be due to an activation of dysfunctional self-related body schemata, which distort body evaluation depending on identity. Double standards related to body fat were characteristic for women with ED, but not for women without ED.