Goal pursuit increases more after dietary success than after dietary failure: examining conflicting theories of self-regulation using ecological momentary assessment.

BACKGROUND: Maintaining a healthy body weight and reaching long-term dietary goals requires ongoing self-monitoring and behavioral adjustments. How individuals respond to successes and failures is described in models of self-regulation: while cybernetic models propose that failures lead to increased self-regulatory efforts and successes permit a reduction of such efforts, motivational models (e.g., social-cognitive theory) make opposite predictions. Here, we tested these conflicting models in an ecological momentary assessment (EMA) context and explored whether effort adjustments are related to inter-individual differences in perceived self-regulatory success in dieting (i.e., weight management). METHODS: Using linear mixed effects models, we tested in 174 diet-interested individuals whether current day dietary success or failure (e.g., on Monday) was followed by self-regulatory effort adjustment for the next day (e.g., on Tuesday) across 14 days. Success vs. failure was operationalized with two EMA items: first, whether food intake was higher vs. lower than usual and second, whether food intake was perceived as more vs. less goal-congruent than usual. Trait-level perceived self-regulatory success in dieting was measured on a questionnaire. RESULTS: Intended self-regulatory effort increased more strongly after days with dietary success (i.e., eating less than usual / rating intake as goal-congruent) than after days with dietary failure (i.e., eating more than usual / rating intake as goal-incongruent), especially in those individuals with lower scores on perceived self-regulatory success in dieting. CONCLUSIONS: Findings support mechanisms proposed by social-cognitive theory, especially in unsuccessful dieters. Thus, future dietary interventions could focus on preventing the decrease in self-regulatory effort after instances of dietary failures and thereby mitigate the potential risk that a single dietary failure initiates a downward spiral into unhealthy eating.

Emotional eating: elusive or evident? Integrating laboratory, psychometric and daily life measures.

PURPOSE: Emotional eating (EE) refers to eating in response to (negative) emotions. Evidence for the validity of EE is mixed: some meta-analyses find EE only in eating disordered patients, others only in restrained eaters, which suggest that only certain subgroups show EE. Furthermore, EE measures from lab-based assessments, ecological momentary assessment (EMA), and psychometric measures often diverge. This paper tested whether the covariance of these three different EE methods can be modeled through a single latent variable (factorial validity), and if so, how this variable would relate to restrained eating (construct validity), Body-Mass-Index (BMI), and subclinical eating disorder symptomatology (concurrent validity). METHODS: 102 non-eating disordered female participants with a wide BMI range completed EE measures from three methods: psychometric questionnaires, a laboratory experiment (craving ratings of food images in induced neutral vs. negative emotion) and EMA questionnaires (within-participant correlations of momentary negative emotions and momentary food cravings across 9 days). Two measures for each method were extracted and submitted to confirmatory factor analysis. RESULTS: A one-factor model provided a good fit. The resulting EElat factor correlated positively with subclinical eating disorder symptoms and BMI but not with restrained eating. CONCLUSIONS: The one-factor solution shows that the EE construct can validly be assessed with three different methods. Individual differences in EE are supported by the data and are related to eating and weight problem symptomatology but not to restrained eating. This supports learning accounts of EE and underscores the relevance of the EE construct to physical and mental health. LEVEL OF EVIDENCE: II (Evidence obtained from well-designed controlled trials without randomization).

Intra-individual Associations of Perceived Stress, Affective Valence, and Affective Arousal with Momentary Cortisol in a Sample of Working Adults.

BACKGROUND: Research pairing ecological momentary assessment (EMA) methodology and ambulatory cortisol during daily life is still rare, as is careful testing of the within-person associations between stress, affect, and cortisol. Using a circumplex approach, we considered both valence and arousal components of affect. PURPOSE: To examine the within-person covariation of momentary cortisol with momentary perceived stress, affective valence, and affective arousal in everyday life. METHODS: 115 working adults (Mage = 41.2; 76% women; 76% white) completed six EMA surveys per day over 3 days. Each assessment included reports of perceived stress and affect (used to construct indicators of affective valence and arousal), followed by a saliva sample (from which cortisol was assessed). Multi-level models were used to examine the momentary associations between perceived stress, affective valence, affective arousal, and cortisol. RESULTS: Moments characterized by higher perceived stress were associated with higher cortisol (p = .036). Affective valence covaried with cortisol (p = .003) such that more positive valence was associated with lower cortisol and more negative valence with higher cortisol. Momentary affective arousal was not related to cortisol (p = .131). When all predictors were tested in the same model, only valence remained a significant predictor of cortisol (p = .047). CONCLUSION: Momentary perceived stress and affective valence, but not affective arousal, were associated with naturalistic cortisol. Cortisol was more robustly associated with affective valence than perceived stress or affective arousal. These findings extend our understanding of how moments of stress and particular characteristics of affective states (i.e., valence but not arousal) may "get under the skin" in daily life.

Clustering individuals' temporal patterns of affective states, hunger, and food craving by latent class vector-autoregression.

BACKGROUND: Eating plays an important role in mental and physical health and is influenced by affective (e.g., emotions, stress) and appetitive (i.e., food craving, hunger) states, among others. Yet, substantial temporal variability and marked individual differences in these relationships have been reported. Exploratory data analytical approaches that account for variability between and within individuals might benefit respective theory development and subsequent confirmatory studies. METHODS: Across 2 weeks, 115 individuals (83% female) reported on momentary affective states, hunger, and food craving six times a day. Based on these ecological momentary assessment (EMA) data we investigated whether latent class vector-autoregression (LCVAR) can identify different clusters of participants based on similarities in their temporal associations between these states. RESULTS: LCVAR allocated participants into three distinct clusters. Within clusters, we found both positive and negative associations between affective states and hunger/food craving, which further varied temporally across lags. Associations between hunger/food craving and subsequent affective states were more pronounced than vice versa. Clusters differed on eating-related traits such as stress-eating and food craving as well as on EMA completion rates. DISCUSSION: LCVAR provides novel opportunities to analyse time-series data in affective science and eating behaviour research and uncovers that traditional models of affect-eating relationships might be overly simplistic. Temporal associations differ between subgroups of individuals with specific links to eating-related traits. Moreover, even within subgroups, differences in associations across time and specific affective states can be observed. To account for this high degree of variability, future research and theories should consider individual differences in direction and time lag of associations between affective states and eating behaviour, daytime and specific affective states. In addition to that, methodological implications for EMA research are discussed.

Further support for the validity of the social appearance anxiety scale (SAAS) in a variety of German-speaking samples.

PURPOSE: Eating disorders (ED) and social anxiety disorder are highly comorbid with potentially shared symptoms like social appearance anxiety (SAA) referring to a fear of being negatively evaluated by others' because of overall appearance. SAA constitutes a risk factor for eating psychopathology and bridges between EDs and social anxiety disorder. METHODS: The present studies examined internal consistency, factor structure, test-retest reliability, gender and age invariance, convergent validity and differences between individuals with and without an ED of a German version of the social appearance anxiety scale (SAAS) in four independent samples (n1 = 473; n2 = 712; n3 = 79; n4 = 33) including adolescents and patients with EDs. RESULTS: Consistently, the SAAS showed excellent internal consistency (ωs ≥ 0.947) and a one-factorial structure. Convergent validity was shown via high correlations of the SAAS with social anxiety (e.g., social interaction anxiety r = 0.642; fear of negative evaluation rs ≥ 0.694), body image disturbance measures (e.g., shape concerns rs ≥ 0.654; weight concerns rs ≥ 0.607; body avoidance rs ≥ 0.612; body checking rs ≥ 0.651) and self-esteem (r = -0.557) as well as moderate correlations with general eating psychopathology (e.g., restrained rs ≥ 0.372; emotional r = 0.439; external eating r = 0.149). Additionally, the SAAS showed gender and age invariance and test-retest reliability after 4 weeks with r = 0.905 in Study 2 and was able to discriminate between individuals with and without an ED in Study 4. CONCLUSION: Hence, the German version of the SAAS can reliably and validly assess SAA in female and male adolescents or adults with or without an ED. Additionally, the SAAS might be used in a therapeutic context to especially target patient groups suffering from EDs with comorbid social anxiety. LEVEL OF EVIDENCE: Level III: Evidence obtained from cohort or case-control analytic studies.

Networks of stress, affect and eating behaviour: anticipated stress coping predicts goal-congruent eating in young adults.

BACKGROUND: Many people aim to eat healthily. Yet, affluent food environments encourage consumption of energy dense and nutrient-poor foods, making it difficult to accomplish individual goals such as maintaining a healthy diet and weight. Moreover, goal-congruent eating might be influenced by affects, stress and intense food cravings and might also impinge on these in turn. Directionality and interrelations of these variables are currently unclear, which impedes targeted intervention. Psychological network models offer an exploratory approach that might be helpful to identify unique associations between numerous variables as well as their directionality when based on longitudinal time-series data. METHODS: Across 14 days, 84 diet-interested participants (age range: 18-38 years, 85.7% female, mostly recruited via universities) reported their momentary states as well as retrospective eating episodes four times a day. We used multilevel vector autoregressive network models based on ecological momentary assessment data of momentary affects, perceived stress and stress coping, hunger, food craving as well as goal-congruent eating behaviour. RESULTS: Neither of the momentary measures of stress (experience of stress or stress coping), momentary affects or craving uniquely predicted goal-congruent eating. Yet, temporal effects indicated that higher anticipated stress coping predicted subsequent goal-congruent eating. Thus, the more confident participants were in their coping with upcoming challenges, the more they ate in line with their goals. CONCLUSION: Most eating behaviour interventions focus on hunger and craving alongside negative and positive affect, thereby overlooking additional important variables like stress coping. Furthermore, self-regulation of eating behaviours seems to be represented by how much someone perceives a particular eating episode as matching their individual eating goal. To conclude, stress coping might be a potential novel intervention target for eating related Just-In-Time Adaptive Interventions in the context of intensive longitudinal assessment.

Emotional eating across different eating disorders and the role of body mass, restriction, and binge eating.

OBJECTIVE: Different subtypes of eating disorders (ED) show dysfunctional eating behaviors such as overeating and/or restriction in response to emotions. Yet, systematic comparisons of all major EDs on emotional eating patterns are lacking. Furthermore, emotional eating correlates with body mass index (BMI), which also differs between EDs and thus confounds this comparison. METHOD: Interview-diagnosed female ED patients (n = 204) with restrictive (AN-R) or binge-purge anorexia nervosa (AN-BP), bulimia nervosa (BN), or binge-eating disorder (BED) completed a questionnaire assessing "negative emotional eating" (sadness, anger, anxiety) and "happiness eating." ED groups were compared to BMI-matched healthy controls (HCs; n = 172 ranging from underweight to obesity) to exclude BMI as a confound. RESULTS: Within HCs, higher BMI was associated with higher negative emotional eating and lower happiness eating. AN-R reported the lowest degree of negative emotional eating relative to other EDs and BMI-matched HCs, and the highest degree of happiness eating relative to other EDs. The BN and BED groups showed higher negative emotional eating compared to BMI-matched HCs. Patients with AN-BP occupied an intermediate position between AN-R and BN/BED and reported less happiness eating compared to BMI-matched HCs. DISCUSSION: Negative emotional and happiness eating patterns differ across EDs. BMI-independent emotional eating patterns distinguish ED subgroups and might be related to the occurrence of binge eating versus restriction. Hence, different types of emotional eating can represent fruitful targets for tailored psychotherapeutic interventions. While BN and BED might be treated with similar approaches, AN-BP and AN-R would need specific treatment modules.

Characterising binge eating over the course of a feasibility trial among individuals with binge eating disorder and bulimia nervosa.

Binge eating disorder and bulimia nervosa are eating disorders that are characterized by recurrent binge eating episodes. The highly contextualized nature of binge eating makes naturalistic research a particularly suitable means of understanding the context within which binge eating occurs. The present study aimed to characterise binge eating days with regards to the frequency and probability of negative affect, food craving, meal skipping, and dietary restriction. In addition, it aimed to examine whether a combined intervention that targets the experience of 'loss of control' over eating can decrease these potential maintenance factors that often precede binge eating episodes. Seventy-eight participants with bulimia nervosa (N = 40) or binge eating disorder (n = 38), who were randomly allocated to a food-specific or general intervention combining inhibitory control training and implementation intentions, completed mood and food diaries over four weeks. Results suggest that negative affect and food craving were elevated on binge eating days, but that dietary restraint and meal skipping did not characterise binge eating days. Moreover, meal skipping, binge eating, restriction, and compensation decreased throughout the intervention period, while negative affect and food craving did not. This suggests that some interventions may successfully reduce binge eating frequency without necessarily decreasing negative affect or food craving, thus pointing to the different routes to targeting binge eating and providing implications for future interventions.

Body-related cognitive distortions (thought-shape fusion body) associated with thin-ideal exposure in female students-An ecological momentary assessment study.

Etiological models of eating disorders (EDs) describe body dissatisfaction (BD)as one of the major influences fostering dysfunctional body-related behaviour and disordered eating behaviour. BD is influenced by repeated exposure to thin ideals that evoke high self-ideal discrepancy and result in body-related cognitive distortions such as thought-shape fusion body (TSF-B). The aim of this study was to investigate the covariation of daily media exposure and the experience of TSF-B in a naturalistic setting. It was further analysed whether TSF-B is associated with self-ideal discrepancy, dysfunctional body-related behaviour, and disordered eating behaviour. Moreover, person-related predictors of TSF-B were explored. Altogether, 51healthy female students (mean age 21.06years, SD = 1.76) participated in an ecological momentary assessment study with four daily surveys during 10consecutive days. Exposure with thin ideals in contrast to exposure to unspecific media contents went along with the experience of TSF-B. TSF-B was associated with higher self-ideal discrepancy and dysfunctional body-related behaviour as well as more pronounced disordered eating behaviour, suggesting that TSF-B is a common phenomenon in young healthy females' everyday life. A main effect of trait measures (e.g., pre-existing BD) on TSF-B was observable but has no moderating effect. Thus, a specific vulnerability has not been detected.

"I will fast tomorrow": Intentions to restrict eating and actual restriction in daily life and their person-level predictors.

OBJECTIVE: Dietary restraint is a common, yet controversial practice to tackle overweight. Yet, despite good intentions to reduce food intake, most restraint-based diets fail to produce long term weight loss. A better understanding of the naturalistic course of daily dieting intentions and their effectiveness in guiding subsequent eating behavior are therefore needed. METHOD: In two studies, participants (n = 49 and n = 59) reported both their state intention to restrict eating on the next day, as well as their actual restriction on that day via smartphone-based evening reports of 12 and 10 days, respectively. Intention-behavior gap scores were calculated as differences between intention at t1 (e.g. evening intention Monday for restriction Tuesday) and restriction at t2 (evening report of actual restraint on Tuesday). Restriction-related trait questionnaires served as predictors of general intention or restriction level, whereas several trait-level disinhibiting eating style questionnaires served as predictors for intention-behavior gaps (difference scores). RESULTS: Daily intentions to restrict were rated higher than the daily actual restrictive behavior. Participants with higher scores on restriction-related questionnaires (restrained eating, dieting, lower intuitive eating) showed higher levels of daily state intention and restriction. Larger state intention-behavior gaps, by contrast, were seen in participants scoring high on trait-level disinhibiting eating styles (emotional eating, stress eating and food craving). DISCUSSION: The results point to potential risk factors of diet failure in everyday life: emotional, stress eating, and food craving are disinhibiting traits that seem to increase intention-behavior gaps. These findings can inform individualized weight-loss interventions: individuals with disinhibiting traits might need additional guidance to avoid potentially frustrating diet failures.

Emotion regulation and emotional eating in anorexia nervosa and bulimia nervosa.

Individuals with anorexia nervosa (AN) and bulimia nervosa (BN) show emotion regulation deficits. While individuals with BN use binge eating to regulate negative affect, individuals with restricting-type AN may use self-starvation for this purpose. The current study examined the emotion regulatory function of over- and undereating in response to different emotional states in women with restrictive AN (n = 54), BN (n = 47), and women without eating disorders (n = 68). Participants completed self-report measures assessing the use of emotion regulation strategies and emotional eating. Both patient groups reported using more dysfunctional and less functional emotion regulation strategies than controls. The BN group reported eating more than usual in response to negative emotions but less than usual in response to positive emotions. In contrast, the AN group reported eating more than usual in response to positive emotions and less than usual in response to negative emotions. More dysfunctional emotion regulation related to eating less in response to negative emotions in the AN group. Less functional emotion regulation related to eating less when being happy in the BN group. The current study highlights the need to differentiate between different eating outcomes and different emotional states when examining emotion effects on food intake.

Malaise with praise: A narrative review of 10 years of research on the concept of Fear of Positive Evaluation in social anxiety.

Social anxiety is characterized by a fear of being negatively evaluated by others (i.e., Fear of Negative Evaluation [FNE]). In 2008, Weeks, Heimberg, and Rodebaugh proposed Fear of Positive Evaluation (FPE) as a second cognitive component in social anxiety. The article presents an overview of FPE, its psycho-evolutionary theoretical foundation and assessment by the Fear of Positive Evaluation Scale as well as relevant psychometric research on demographic characteristics. The relationship of FPE with a wide range of established dimensions from clinical, personality, and social psychology (i.e., self-esteem, perfectionism, or quality of life) will be reviewed. The role of FPE for psychological comorbidities such as other anxiety disorders, depression, eating, and substance use disorders as well as for treatment of social anxiety will be discussed. Future research might address questions of causality of FPE relative to related constructs, further data on psychometric properties, as well as on its independence from FNE in longitudinal studies. In sum, FPE seems to be a valid and reliable construct that explains cognitions, emotions, and behavior related to social anxiety at subclinical and clinical levels and therefore enriches the psychometric repertoire in the fields of social psychology, personality, and clinical psychology.

Development and preliminary validation of the Salzburg Stress Eating Scale.

Stress-related eating has long been a focus of study in several disciplines. Currently available psychometric scales conflate stress-related eating with emotional eating despite that not all stress states can be subsumed under some form of specific emotion. Moreover, existing measures primarily assess increased food intake in response to emotions and stress, thus ignoring evidence of decreased food intake in response to stress. Therefore, we drew from established stress concepts to develop the first genuine stress-related eating scale (Salzburg Stress Eating Scale [SSES]) in both German and English versions. In the SSES higher scores indicate eating more when stressed and lower scores indicate eating less when stressed. In study 1 (n = 340), the German SSES was found to have a one-factor structure (α = 0.89). SSES scores were weakly or moderately correlated with other eating-related constructs (e.g., emotional eating, body mass index [BMI]), and weakly correlated or uncorrelated with non-eating-related constructs (e.g., impulsivity, perceived stress); in addition, women had higher scores than men. Perceived stress moderated the association between stress eating and BMI, such that higher SSES scores were significantly related to higher BMI in individuals with high perceived stress, but not in individuals with low perceived stress. In studies 2 (n = 790) and 3 (n = 331), factor structure, internal consistency, and associations with sex and BMI were replicated for both German and English versions of the SSES. Hence, the SSES represents a psychometrically sound tool for the measurement of stress-related eating.

Smoking, Stress Eating, and Body Weight: The Moderating Role of Perceived Stress.

BACKGROUND: Some individuals respond to stress with increased food intake while others reduce their food intake. Smokers often report using smoking to cope with stress and have a lower body weight than nonsmokers on average. Thus, smokers may tend to eat less when stressed, which may partly explain their lower body weight as compared to nonsmokers. In turn, nonsmokers may tend to eat more when stressed, which may partly explain their higher body weight as compared to smokers. OBJECTIVE: To examine the interplay between smoking and stress-related eating. METHODS: N = 314 (78% female, 14% smokers) participants reported whether they were current smokers, their body height and weight and completed the Salzburg Stress Eating Scale and the Perceived Stress Scale. RESULTS: Smokers did not differ from nonsmokers in body mass index (BMI), stress eating and perceived stress. When perceived stress was high, however, nonsmokers reported eating more and smokers reported eating less than usual. Moreover, in individuals with high perceived stress, being a smoker was indirectly related to lower BMI through eating less when stressed and being a nonsmoker was indirectly related to higher BMI through eating more when stressed. CONCLUSION: Smokers most likely use smoking instead of eating to cope with stress and, therefore, food intake and body weight decrease in stressed smokers. After smoking cessation, these individuals may be more susceptible to weight gain when-similar to nonsmokers-eating instead of smoking is used to cope with stress.

Food cravings in everyday life: An EMA study on snack-related thoughts, cravings, and consumption.

Food craving refers to an intense desire to consume a specific food and is regularly experienced by the majority of individuals. Yet, there are interindividual differences in the frequency and intensity of food craving experiences, which is often referred to as trait food craving. The characteristics and consequences of trait and state food craving have mainly been investigated in questionnaire-based and laboratory studies, which may not reflect individuals' behavior in daily life. In the present study, sixty-one participants completed the Food Cravings Questionnaire-Trait-reduced (FCQ-T-r) as measure of trait food craving, followed by seven days of Ecological Momentary Assessment (EMA), during which they reported snack-related thoughts, craving intensity, and snack consumption at five times per day. Results showed that 86 percent of reported snacks were high-caloric, with chocolate-containing foods being the most often reported snacks. Individuals with high FCQ-T-r scores (high trait food cravers, HCs) thought more often about high-calorie than low-calorie snacks whereas no differences were found in individuals with low FCQ-T-r scores (low trait food cravers, LCs). Further, the relationship between craving intensity and snack-related thoughts was stronger in HCs than in LCs. Higher craving intensity was associated with more consumption of snacks and again this relationship was stronger in HCs than in LCs. Finally, more snack-related thoughts were related to more frequent consumption of snacks, independent of trait food craving. Thus, HCs are more prone to think about high-calorie snacks in their daily lives and to consume more snack foods when they experience intense cravings, which might be indicative of a heightened responding towards high-calorie foods. Thus, trait-level differences as well as snack-related thoughts should be targeted in dietary interventions.

Criticism hurts everybody, praise only some: Common and specific neural responses to approving and disapproving social-evaluative videos.

Social evaluation is a ubiquitous feature of daily interpersonal interactions and can produce strong positive or negative emotional reactions. While previous research has highlighted neural correlates of static or dynamic facial expressions, little is known about neural processing of more naturalistic social interaction simulations or the modulating role of inter-individual differences such as trait fear of negative/positive evaluation. The present fMRI study investigated neural activity of 37 (21 female) healthy participants while watching videos of posers expressing a range of positive, negative, and neutral statements tapping into several basic and social emotions. Unpleasantness ratings linearly increased in response to positive to neutral to negative videos whereas arousal ratings were elevated in both emotional video conditions. At the whole brain level, medial prefrontal and rostral anterior cingulate cortex activated strongly in both emotional conditions which may be attributed to the cognitive processing demands of responding to complex social evaluation. Region of interest analysis for basic emotion processing areas revealed enhanced amygdala activation in both emotional conditions, whereas anterior and posterior insula showed stronger activity during negative evaluations only. Individuals with high fear of positive evaluation were characterized by increased posterior insula activity during positive videos, suggesting heightened interoception. Taken together, these results replicate and extend studies that used facial expression stimuli and reveal neurobiological systems involved in processing of more complex social-evaluative videos. Results also point to vulnerability factors for social-interaction related psychopathologies.

Excess after stress-A three-study validation of the salzburg stress drinking scale as a new tool to measure the stress-drinking relationship.

Stress frequently influences a person's propensity to drink alcohol. Inter-individual differences in such stress-related drinking can be assessed through psychometric scales; however, available questionnaires conflate stress- with emotion-related reasons to drink and ignore evidence of decreased alcohol consumption in response to stress. Therefore, we developed a genuine stress-drinking scale (Salzburg Stress Drinking Scale; SSDS), adapted from the Salzburg Stress Eating Scale, and assessed its psychometric properties. In study 1 (n = 639), the SSDS was found to have a one-factor structure, excellent internal consistency, and acceptable test-retest reliability. SSDS scores were significantly correlated with other measures assessing emotional drinking, but uncorrelated with general alcohol pathology and other health-relevant consummatory behaviors such as stress-related eating or nicotine consumption. In addition, no significant sex differences arose. In study 2 (n = 42) patients with an alcohol use disorder or addiction scored significantly higher on the SSDS compared to healthy controls. In an Ecological Momentary Assessment study 3 (n = 67), the SSDS showed partial ecological validity through significant relationships with daily alcohol consumption, but not daily stress-drinking relationships. In sum, the SSDS represents a psychometrically sound tool for the measurement of stress-related drinking and complements a battery of stress-related changes in health-relevant behaviors.

Toward Individualized Prediction of Binge-Eating Episodes Based on Ecological Momentary Assessment Data: Item Development and Pilot Study in Patients With Bulimia Nervosa and Binge-Eating Disorder.

BACKGROUND: Prevention of binge eating through just-in-time mobile interventions requires the prediction of respective high-risk times, for example, through preceding affective states or associated contexts. However, these factors and states are highly idiographic; thus, prediction models based on averages across individuals often fail. OBJECTIVE: We developed an idiographic, within-individual binge-eating prediction approach based on ecological momentary assessment (EMA) data. METHODS: We first derived a novel EMA-item set that covers a broad set of potential idiographic binge-eating antecedents from literature and an eating disorder focus group (n=11). The final EMA-item set (6 prompts per day for 14 days) was assessed in female patients with bulimia nervosa or binge-eating disorder. We used a correlation-based machine learning approach (Best Items Scale that is Cross-validated, Unit-weighted, Informative, and Transparent) to select parsimonious, idiographic item subsets and predict binge-eating occurrence from EMA data (32 items assessing antecedent contextual and affective states and 12 time-derived predictors). RESULTS: On average 67.3 (SD 13.4; range 43-84) EMA observations were analyzed within participants (n=13). The derived item subsets predicted binge-eating episodes with high accuracy on average (mean area under the curve 0.80, SD 0.15; mean 95% CI 0.63-0.95; mean specificity 0.87, SD 0.08; mean sensitivity 0.79, SD 0.19; mean maximum reliability of rD 0.40, SD 0.13; and mean rCV 0.13, SD 0.31). Across patients, highly heterogeneous predictor sets of varying sizes (mean 7.31, SD 1.49; range 5-9 predictors) were chosen for the respective best prediction models. CONCLUSIONS: Predicting binge-eating episodes from psychological and contextual states seems feasible and accurate, but the predictor sets are highly idiographic. This has practical implications for mobile health and just-in-time adaptive interventions. Furthermore, current theories around binge eating need to account for this high between-person variability and broaden the scope of potential antecedent factors. Ultimately, a radical shift from purely nomothetic models to idiographic prediction models and theories is required.

Predicting food craving in everyday life through smartphone-derived sensor and usage data.

Background: Food craving relates to unhealthy eating behaviors such as overeating or binge eating and is thus a promising target for digital interventions. Yet, craving varies strongly across the day and is more likely in some contexts (external, internal) than in others. Prediction of food cravings ahead of time would enable preventive interventions. Objective: The objective of this study was to investigate whether upcoming food cravings could be detected and predicted from passive smartphone sensor data (excluding geolocation information) without the need for repeated questionnaires. Methods: Momentary food craving ratings, given six times a day for 14 days by 56 participants, served as the dependent variable. Predictor variables were environmental noise, light, device movement, screen activity, notifications, and time of the day recorded from 150 to 30 min prior to these ratings. Results: Individual high vs. low craving ratings could be predicted on the test set with a mean area under the curve (AUC) of 0.78. This outperformed a baseline model trained on past craving values in 85% of participants by 14%. Yet, this AUC value is likely the upper bound and needs to be independently validated with longer data sets that allow a split into training, validation, and test sets. Conclusions: Craving states can be forecast from external and internal circumstances as these can be measured through smartphone sensors or usage patterns in most participants. This would allow for just-in-time adaptive interventions based on passive data collection and hence with minimal participant burden.

Does stress eat away at you or make you eat? EMA measures of stress predict day to day food craving and perceived food intake as a function of trait stress-eating.

Eating behaviour can be driven by non-homeostatic factors like stress. Both increased and decreased food intake in response to stress has been documented, but it has remained difficult to identify a trait that predicts who shows either pattern. Thus, we collected naturalistic data from Ecological Momentary Assessment in combination with the trait-level Salzburg Stress Eating Scale (SSES). In study 1, 97 individuals completed the SSES and 6 daily reports about stress, food craving and perceived food intake across 8 days, whereas in study 2, 83 diet-interested participants completed the same measures at 4 daily prompts across 14 days. Consistent across both studies, multilevel modelling revealed that participants with high SSES-scores showed relatively more positive intra-day stress-craving relationships than those with low SSES-scores. On the day level, stress also predicted perceived food intake as a function of SSES-scores. Controlling for negative affect did not alter results. Results support an individual difference model of stress-eating where decrease vs increase of eating depends on SSES-scores. In affected individuals stress influences simultaneous food craving but might exhibit cumulative or delayed effects on food intake. Furthermore, the SSES provides a valid instrument for identifying at risk individuals and for tailoring interventions.