Methods
Participants
A total of 769 participants completed this study (67.9% female, mean age = 27.99 years, SD = 12.17 years, range = 17 to 72 years, mean BMI = 26.25, SD = 8.08). Of these, 290 were recruited from the general community (67.9% female, mean age = 27.54 years, SD = 9.57 years, mean BMI = 24.42, SD = 6.70), 283 were recruited from a sample of first year psychology students from The University of Sydney (52.3% female, mean age = 20.23, SD = 4.8 years, mean BMI = 22.58, SD = 4.12), 76 were recruited as part of studies assessing new treatments for binge eating (100% female, mean age = 35.97 years, SD = 17.68, mean BMI = 28.01, SD = 7.23), and 120 were recruited as part of a study on obesity (58% female, mean age = 42.31 years, SD = 9.51 years, mean BMI = 38.22, SD = 7.23).
Design
Dependent variables were participants’ scores on the various measures, including the EBQ, binge eating severity (as determined by a semi-structured diagnostic interview, the EDE, or its companion self-report questionnaire- the EDE-Q), and BMI.
Measures
For the purpose of assessing the EBQ’s construct validity and relevance to binge eating, the test battery consisted of measures that are known to correlate with binge eating and/or eating disorder severity [
3,
4,
8,
10,
19]. Together, these measures assessed body mass (BMI), overall mood and distress (Depression Anxiety Stress Scales; DASS-21), eating disorder symptoms and related behaviours (EDE-Q and DEBQ), eating disorder related cognitions (EDE-Q and EDBQ), negative core-beliefs (Eating Disorders Core Beliefs Questionnaire; ED-CBQ) and poor distress tolerance (Difficulty in Emotion Regulation Scale; DERS).
The Eating Beliefs Questionnaire (EBQ) [
10]. The EBQ is a 27 item self-report metacognitive measure, consisting of two subscales that assesses positive and negative thoughts about eating and urges to eat when not hungry. An example of a positive item is “Eating helps me to feel calm”, and an example of a negative item is “I have no willpower in relation to food”. Participants rate how much they agree with each of the items from 1 (strongly disagree) to 5 (strongly agree).
Body Mass Index (BMI). The height and weight of participants was recorded so that BMI could be determined. BMI is calculated by dividing an individual’s weight in kilograms by their height in metres squared (BMI = kg/m
2). BMI categories indicate if an individual’s body weight is within a healthy range. Individuals with BMIs above and below the healthy weight range are at greater risk of diseases such as cardio-vascular disease and diabetes [
23].
The Eating Disorder Examination (EDE) [
7]. The EDE is a clinician-administered semi-structured interview which assesses eating disorder symptoms and associated features over the previous 28 days. The EDE provides a global score as well as four subscale scores: dietary restraint, eating concern, weight concern and shape concern. Examples of items include: “Have you been deliberately trying to limit the amount of food you eat to influence your shape and weight (whether or not you have succeeded?”, and “Have you had a definite desire to have a totally flat stomach?”. The EDE also includes items relating to the frequency and severity of binge eating episodes (e.g., “Over the past 28 days, how many times have you eaten what other people would regard as an unusually large amount of food (given the circumstances)?”). Items are rated from 0 to 6, with higher scores indicating greater frequency or severity of symptoms. The EDE is considered to be the gold-standard measurement tool for the assessment of eating disorders [
24].
The EDE-Q [
11] is the self-report questionnaire version of the gold-standard interview. The EDE-Q has been found to demonstrate good internal consistency, construct validity, and test-retest reliability [
19]; Cronbach’s α = .95 for the EDE-Q global score in the present study.
Depression Anxiety Stress Scales (DASS-21) [
25]. The DASS-21 is a 21-item self-report scale consisting of three subscales each containing 7 items that measure the severity of depression (e.g., “I tend to feel down-hearted and blue”), anxiety (“I felt I was close to panic”) and stress (e.g., “I found it difficult to relax”) symptoms occuring over the past fortnight. The DASS-21 has been found to be a valid and reliable measure with good psychometric properties e.g., [
26]; Cronbach’s α = .94 for the whole measure in the present study.
Dutch Eating Behaviour Questionnaire (DEBQ) [
17]. The DEBQ is a self-report questionnaire measuring eating behaviours and related attitudes. The DEBQ consists of three subscales: restrained eating, emotional eating and external eating; only the second two subscales were included in this study. The emotional eating scale (13 items) assesses the extent to which emotional cues trigger eating (e.g., “Do you have a desire to eat when you are irritated?”), while the external eating scale (10 items) assesses the extent to which external/environmental cues trigger eating (e.g., “If food tastes good to you, do you eat more than usual?”). Both scales were found to demonstrate adequate internal consistency [
17]; Cronbach’s α = .94 for the emotional eating scale and Cronbach’s α = .79 for the external eating scale in the present study.
Eating Disorders Beliefs Questionnaire (EDBQ) [
15]. The EDBQ is a 32-item self-report questionnaure which assesses core beliefs and underlying assumptions thought to be related to the development and maintenance of eating disorders. Participants are asked to endorse items according to how much they believe or feel them to be true from 0 (“I do not usually believe this at all”) to 100 (“I am usually completely convinced that this is true”). Higher scores indicated greater frequency and intensity of eating disordered beliefs The EDBQ contains 4 subscales: negative self-beliefs (e.g., “I’m stupid”), acceptance by others (e.g., “If my bottom is small people will take me seriously”), self-acceptance (e.g., “If my body is lean I can feel good about myself”) and control over eating (e.g., “If I binge and vomit I can stay in control”). An examination of the psychometric properties of this measure found good internal consistency, good test-retest reliability and adequate construct validity [
27]. In the present study, Cronbach’s alphas ranged from .87–.96 for the subscale scores.
Eating Disorders Core Beliefs Questionnaire (ED-CBQ) [
28]. The ED-CBQ is a 40 item self-report measure designed to measure self beliefs relevant to eating disorders. Participants rate each item for how much they believe/feel each item to be true most of the time. The ED-CBQ consists of 5 subscales: self-loathing (e.g., “putrid”), unassertiveness/inhibited (e.g., “meek”), high standards for self (e.g., “perfectionistic”), demanding/need help and support (e.g., “needy”), and abandoned/isolated (e.g., “abandoned”). Results of the initial validation study found that the ED-CBQ demonstrated adequate internal consistency and contruct validity [
28]; Cronbach’s α = .92 for the whole measure in the present study.
Difficulty in Emotion Regulation Scale (DERS) [
29]. The DERS is a 36-item self-report questionnaire that assesses difficulties in emotion regulation. The DERS has 6 subscales: non-acceptance of emotional responses (e.g., “When I am upset, I become angry with myself for feeling that way”), difficulty engaging in goal-directed behaviour (e.g., “When I am upset I have difficulty getting work done”), impulse control difficulties (e.g., “When I am upset, I become out of control”), lack of emotional awareness (e.g., “I have no idea how I am feeling”), limited access to emotional regulation strategies (e.g., “When I am upset, I believe that wallowing in it is all I can do”), and lack of emotional clarity (e.g., “I have difficulty making sense out of my feelings”). Using a scale of 1 (almost never) to 5 (almost always), participants are asked to indicate how often the items apply to themselves; higher DERS scores indicate greater emotion dysregulation. The initial validation study found the DERS subscales had good internal consistency, good test–retest reliability, and adequate construct and predictive validity [
29]; Cronbach’s α = .86 for the whole measure in the present study.
Procedure
Participants completed either the full battery of questionnaires or a brief test battery (consisting of the EBQ, the EDE-Q and the DASS-21 only), and their weight and height was recorded to determine their BMI. Participants recruited from the university completed the full test battery online, and participants recruited from the general community completed the brief test battery online. Online participants completed the questionnaires in their own time and could take breaks as required. In addition, the order of presentation of the questionnaires was randomised in the online data collection in an attempt to reduce potential fatigue effects. Clinical participants completed the brief test battery as well as completing an EDE interview administered by a doctoral level clinical psychology student who had received training in the administration of the EDE, under supervision by a senior clinical psychologist. Data for clinical participants was collected as part of ongoing treatment trials.
Test-retest
In total, test-retest data was collected from 63 participants (76.2% female, mean age = 27.68 years, SD = 15.68 years, mean BMI = 24.78, SD = 5.41) who completed the EBQ a second time after an interval of at least 2 weeks. Thirty-five participants from the university sample completed the EBQ a second time following an interval of two weeks (57.1% female, mean age = 19.82 years, SD = 3.5 years, mean BMI = 22.98, SD = 4.12). Sixteen treatment-seeking participants with BN who had been allocated to a waitlist condition completed the test battery a second time following an interval of six weeks (100% female, mean age = 22.31 (SD = 3.51), mean BMI = 24.16 (SD = 3.68)), twelve treatment-seeking participants with BED also allocated to waitlist condition completed the test battery a second time after an interval of ten weeks (100% female, mean age = 57.33, SD = 11.7, mean BMI = 31.15, SD = 6.4).
Treatment
EBQ scores were collected from two samples of individuals who participated in randomised controlled trials (RCTs) examining the efficacy of psychological treatments for binge eating. In both cases, participants were randomly allocated to either the treatment or waitlist conditions. For both RCTs, diagnosis was identified by a trained doctoral level clinical psychology student (under supervision by an experienced clinical psychologist) using the EDE semi-structured interview, and responses on self-report measures, including the EBQ, were completed at assessment (pre) and after the treatment/waitlist (post) for both groups.
RCT 1
Thirty-two women with a diagnosis of Bulimia Nervosa were recruited to participate in a randomised controlled trial (RCT) of a 6-week group psychological intervention as part of a research trial run at the University of Sydney. This intervention was a manualised group therapy program based on Attention Training Therapy (ATT) originally designed for the treatment of panic disorder and social phobia [
30‐
32] . This ATT program was modified to focus on the treatment of binge eating, the program aimed to address binge eating by teaching patients to shift their attention when they experience urges to eat, and to gain the skill of thoughtful eating. Sixteen participants were randomly allocated to receive 6 weeks of group treatment for binge eating and the other sixteen participants were randomly allocated to a waitlist condition of equal duration (100% female, Mean age = 22.31 years, SD = 3.51, Mean BMI = 24.16, SD = 3.68).
RCT 2
Twenty-three women with a diagnosis of Binge Eating Disorder were recruited to participate in a randomised controlled trial (RCT) of a new 10-week individual psychological intervention as part of a research trial run at the University of Sydney. This intervention was a manualised individual therapy program based on Eye Movement Desensitisation and Reprocessing (EMDR) which has been found to be effective in the treatment of Posttraumatic Stress Disorder (PTSD) [
33]. Eleven participants were randomly allocated to receive 10 weeks of individual treatment for binge eating (100% female, Mean age = 52.09 years, SD = 18.13 years, Mean BMI = 32.58, SD = 4.68) and the other twelve participants were randomly allocated to a waitlist condition of equal duration (100% female, Mean age = 57.33 years, SD = 11.7 years, Mean BMI = 31.15, SD = 6.4).
Discussion
The purpose of this study was to examine the validity of the two-factor model of the Eating Beliefs Questionnaire (EBQ) [
10] by conducting a CFA with a large homogenous sample. This study also aimed to assess the psychometric properties, validity and reliability of the EBQ using both a clinical sample of treatment-seeking patients with BN or BED, and a non-clinical sample.
The results of the CFA provided support for the two-factor model proposed by Groves et al. [
10] in the development paper; a two-factor model (negative beliefs and positive beliefs) was found to provide a better fit to the data than a one-factor solution. Following an assessment of the psychometric and theoretical value of the 27 original items, the authors agreed to remove 11 items that had demonstrated relatively poor psychometric value with either low communality, low regression weight or high standardised residual weight. This resulted in a 16 item scale (7 items loading onto the negative beliefs factor and 9 items loading onto the positive beliefs factor). The two-factor solution was found to provide adequate-to-good fit to the 16-item scale, representing an improvement in fit for the shorter version of the questionnaire compared to the original 27-item scale.
The psychometric properties of the 16-item EBQ, and its two subscales, were assessed. Overall, the EBQ was found to be a valid and reliable measure with evidence for its psychometric properties. The total EBQ and its subscale scores were found to have good internal consistency across the different sample groups. Furthermore, the EBQ and subscales showed good test-retest reliability in both a clinical and non-clinical sample, across intervals of 2 to 10 weeks.
Good convergent validity was evidenced by the significant correlations between the EBQ scores and relevant measures of eating disordered and related psychopathology, including BMI (
r = .25 to .36), number of binge episodes, EDE-Q subscales, DASS-21 subscales, eating disorder measures (EDBQ, ED-CBQ and DEBQ), and a measure of poor emotional regulation (DERS). Of particular interest is the strong positive correlations (
r > .70, bolded in Table
5) found between the EBQ Negative Beliefs Subscale (NBS) and EDE-Q Global Score and EDE-Q Eating Concern Subscale. As well as the negative correlations found between EBQ scores and the ED-CBQ High Standards for Self Subscale score (italicised in Table
5). These findings are consistent with the literature as the ED-CBQ High Standards for Self Subscale identifies positive beliefs about the self (e.g., “I am conscientious”), whereas binge eating or general eating disordered behaviour is thought to be associated with poor self-esteem [
36,
37], this is supported by the significant positive correlations identified between EBQ scores and ED-CBQ Self-loathing subscale, and the ED-CBQ Negative Self Beliefs subscale. These findings not only demonstrate the convergent validity of the EBQ scales, but also provide evidence for the relevance of the metacognitive beliefs being measured by the EBQ – positive and negative beliefs about food and eating. These results indicate that these two types of metacognitive beliefs are related to eating disorder symptomatology (EDE-Q), increased BMI, measures of other beliefs relevant to eating disorders (EDBQ, ED-CBQ, & DEBQ) and a measure of emotion dysregulation (DERS). However, it is important to note that although the order of questionnaire presentation was randomised to reduce the potential impact of testing fatigue, the participants completing the full test battery may have experienced fatigue effects.
Scores on the EBQ and its subscales were found to differentiate between subgroups of participants. EBQ scores were significantly higher for participants recruited from clinical samples (BN, BED and obesity studies) compared to scores of participants recruited from non-clinical sites (university and general community). EBQ scores were significantly higher for participants who self-reported regular binge eating compared to scores of participants who reported no presence of binge eating. In addition, EBQ scores were significantly higher for participants who had a BMI in the overweight range or greater compared to scores of participants with a BMI in the normal range. It most likely that the relationship between higher BMI and elevated EBQ scores is driven by the high co-morbidity of increased body-weight and difficulties with problematic eating behaviour, including binge eating [
3,
4].
EBQ scores were also found to be responsive to psychological treatment in two different RCT treatment studies. EBQ total scores were found to be significantly lower at post-treatment for participants who received treatment compared to participants allocated to waitlist. Participants with a diagnosis of BN allocated to a 6 week group ATT therapy treatment showed a significant reduction in EBQ total score and NBS scores, but not PBS scores. Participants with a diagnosis of BED allocated to a 10 week individual EMDR-based therapy treatment showed a significant reduction in scores across EBQ total, NBS and PBS subscales. Differences in the results between these two trials can be explained by the differences in the treatment modality (ATT or EMDR based therapies), delivery (group or individual) and dose (6 or 10 weeks), as well as pre-existing differences between the patients involved in the two different trials (BN compared to BED). Effect sizes were larger for the EMDR treatment trial with BED. This is likely because patients allocated to treatment in the BED trial received 10 weeks of individual treatment. Therefore, these patients received a higher dose of treatment in terms of the number of sessions (10 versus 6), but also due to the nature of the delivery of the treatment as they had individual sessions compared to patients in the BN trial who received 6 weeks of group treatment. Although the there was no significant difference identified between pre and post scores on the PBS for those in the BN group ATT therapy trial, the observed power for the comparisons for the PBS was low, so inferences cannot be drawn about the effect in this case. However, a possible explanation for why the effect size was smaller for the PBS than for the NBS is that the ATT treatment used in this trial targeted the patients’ sense of loss of control over urges to binge eat, but did not target positive beliefs about eating. Indeed, across both trials, the change between pre and post treatment scores was greater for the NBS than the PBS. This finding may indicate that negative beliefs are easier to shift in treatment than positive beliefs are, or perhaps that treatments are usually geared towards building up the client’s sense of control over their eating, but neglect to address their beliefs that eating/food helps them to cope. Future studies should examine whether treatments that also address the positive beliefs about eating lead to better long-term outcomes.
One limitation of the current study is the relatively small size of the treatment-seeking eating disordered sample that was used to assess the test-retest reliability and sensitivity to treatment of this measure. As a result, our knowledge on the utility of this measure with eating disorder patients remains limited. For example, we were unable to calculate group norms for patients with a diagnosis of BN versus BED. We were also limited by the fact that the psychological interventions being administered in the two RCTs described in this paper were novel treatments, with no comparison with an evidence-based treatment such as Enhanced Cognitive Behavioural Therapy (CBT-E) [
38]. Therefore, future studies should examine the validity of this measure in a large treatment-seeking eating disordered sample to provide clinically useful normative data, and also assess the EBQ’s sensitivity to treatment in the context of an evidence-based CBT treatment program for binge eating.
A further limitation is that the EBQ does not provide a measure of the third type of beliefs that Cooper, Wells and Todd [
8] identified in their model of BN as playing an important role in perpetuating binge eating behaviour, permissive beliefs about eating. In order for the EBQ to provide a thorough assessment of the three types of beliefs hypothesised by Cooper et al. to be important to the maintenance of binge eating behaviour, it is recommended that future research develop additional items for the EBQ that assess permissive beliefs about binge eating [
8].
However, as this study used a large and diverse sample, this paper offers a thorough assessment of the psychometric properties of the EBQ, including test-retest reliability and sensitivity to treatment, across both the general community, but also in a treatment-seeking eating disordered clinical sample. Moreover, the number and variety of relevant measures included in the test-battery allowed us to assess the construct validity of the EBQ, not only against measures of eating disordered behaviours and body mass index, but also with other measures of cognitions and beliefs that have been hypothesised to be relevant to the development and perpetuation of binge eating behaviour such as poor emotional regulation [
36,
37], negative beliefs about the self [
8,
39], and body shape concerns [
40].
Conclusion
The present study validates an existing measure of positive and negative metacognitive beliefs about eating with a clinical and non-clinical sample, providing valuable information about the utility of the EBQ as a measure for use in both clinical and research settings. This measure is unique and one of only a few cognitive measures that specifically addresses beliefs relevant to binge eating, a behaviour common to BN, atypical eating disorders and, more specifically, BED patients. The EBQ provides a valuable tool for assessing and measuring change in key maintaining cognitions during the treatment of binge eating. Clinicians can also use the EBQ as tool to help inform formulation and treatment planning for clients seeking treatment for binge eating; clinicians can observe which items on the EBQ clients endorse most strongly and use these responses to plan an individualised and targeted treatment program to address problematic beliefs about food and binge eating held by their client.
Overall, these findings indicate that the EBQ is a psychometrically sound self-report measure that can be used to assess the positive and negative beliefs about eating that are thought to contribute to the maintenance of binge eating behaviour in eating disordered individuals. The EBQ provides a reliable cognitive measure that has been found to be sensitive to psychological treatment, suggesting that the EBQ could be particularly useful in assessing the outcome of cognitive therapy, or the impact of any intervention, on the underlying metacognitive beliefs about positively and negatively perceived aspects of binge eating.