Introduction

Obesity, as a serious medical condition, is increasing all over the world, among both developing and developed countries [1]. The World Health Organization (WHO) considers obesity as a global epidemic [2]. Epidemiological studies show a particularly high prevalence of obesity in the US. In the US, between 2011 and 2012, 1/3 of American adults were obese (37.1 % of men and 56.6 % of women) [3]. Flegal et al. [4] estimated the 2007–2008 US prevalence of obesity to be 32.2 % among men and 35.5 % among women. Moreover, they reported that obesity rates increased between 1988–1994 and 1999–2000.

Based on a systematic review of the published studies from 1990 to 2008, Berghöfer et al. [5] reported that in European countries, the prevalence of obesity ranged from 4.0 to 28.3 % in men and from 6.2 to 36.5 % in women. Jonghorbani and colleagues [6] found that 49.9 % of the Iranian populations aged 15–65 years were obese. The proportions of overweight and obesity were 42.9 % among men and 56.9 % among women, and 10.9 % among men and 24.5 % among women, respectively. Bahrami and colleagues [7] collected data from 8,999 participants between 2002 and 2005. The adjusted rates for overweight and obesity among Iranian population were 62.2 and 28.0 %, respectively, which were comparable to the rates in the United States (i.e., 65.2 and 30.4 %).

Considering the high and increasing prevalence of obesity, selecting effective treatment strategies for obesity is crucial. Different interventions, such as life style modification (including regimen and increasing physical activity and exercise), pharmacotherapy and bariatric surgery, have been proposed for the treatment of obesity. Bariatric surgery is a cost-effective surgery that leads to a significant weight reduction [8–10]. Numerous studies that have investigated comorbid psychological problems and psychopathology among obese individuals, especially among the morbidly obese, have reported high levels of eating, weight and shape concerns, distorted cognitions and behaviors related to eating, depression, anxiety, poor impulse control, low self-esteem and quality of life among them [11–13]. Despite the effectiveness of bariatric surgery for weight loss, several studies have revealed that preoperative and postoperative psychological problems can adversely influence the outcome of the surgery. In other words, psychological characteristics such as irritability, criticism of others, lack of sense of coherence [14, 15], binge eating [16–18] and depression [19] were shown to be negative predictors of weight loss at the follow-up, whereas receiving psychological treatment before surgery for substance abuse or psychiatric comorbidity [20], high self-esteem and good mental health predicted more weight loss [21]. Therefore, some studies have advocated for pre-surgical and postsurgical psychological assessment and intervention for obese individuals undergoing bariatric surgery; however, a standard protocol that targets psychopathological mechanism of obesity is not yet available [22]. Further investigation of cognitive, emotional and behavioral factors that maintain obesity could improve knowledge about this population, inform the development of psychological interventions for obesity, and thereby improve outcomes of bariatric surgery.

The purpose of the present study was to compare obese women candidate for surgery and normal weight women with regard to early maladaptive schemas (EMSs), difficulties in emotion regulation (DER) and binge eating (BE). There is good reason to believe that these factors have potential relevance for obese populations.

Jeffrey Young [23] assumed that EMSs emerge during childhood and adolescence due to early damaging experiences, such as frustration of needs, being victimized, being traumatized, excessive gratification of needs and extend by adulthood experiences. Obese patients were found to hold EMSs more firmly than normal weight individuals [24–26].

Gratz and Roemer [27] reviewed the literature and different theoretical perspectives on emotion regulation, and postulated that emotion regulation includes six components: awareness of emotions, acceptance of negative emotions, the ability to control impulses in the presence of intense emotions, the ability to follow preferred goals while experiencing intense emotions, and the ability to acquire appropriate and flexible strategy for emotion regulation consistent with individual’ goals and demands of the context. The absence of any of these components result in DER. Emotional eating was studied in obese patients and it was found that these patients are more prone to eat when experiencing negative emotions than normal weight ones [28–30]. However, to our knowledge, DER has not been examined in obese individuals.

Binge eating, defined as excessive food intake along with feeling loss of control over eating in the absence of compensatory behaviors as seen in bulimia nervosa, has been found to be common among obese patients, and is often suggested to be a factor in the maintenance of obesity [31–34]. However, binge eating pathology in obese individuals as compared to normal weight individuals has not been studied adequately in Iran.

Materials and methods

Sample

The study sample consisted of two groups: obese women (n = 60) and normal weight women (n = 60). All participants were women who were recruited through a convenience sampling method. Obese participants were drawn from patients who were referred to the obesity clinic of Rasool Akram Hospital of Tehran University of Medical Sciences. Inclusion criteria were: (1) BMI ≥ 40, or BMI = 34–39.9 if there was comorbidity (i.e., medical diseases), and (2) being a candidate for bariatric surgery as determined by the medical team. Those with mental retardation, body dysmorphic disorder and psychotic disorders were not approved for surgery by the medical team. The normal weight group consisted of women with a BMI between 18 and 24.90, who were recruited from the staff of Tehran University of Medical Sciences, staff of Agriculture Bank and staff of a local medical center. The study was approved by the Minimally Invasive Surgery Research Center of Tehran University of Medical Sciences.

Measures

After obtaining informed consent from participants who agreed to take part in the study, each participant completed a set of questionnaires including demographic information, the Young Schema Questionnaire-Short Form (YSQ-SF), Difficulties in Emotion Regulation Scale (DERS) and the Binge Eating Scale (BES).

The YSQ-SF [35] is a 75-item, self-report measure which assesses 15 EMSs of the 18 EMSs that was introduced by Jeffrey Young. EMSs are categorized into five broad domains comprising (1) Disconnection and Rejection domain (Abandonment, Emotional deprivation and Social isolation); (2) Impaired Autonomy domain (Dependence, Vulnerability to harm, Failure and Enmeshment); (3) Impaired Limits domain (Entitlement and Insufficient Self-Control); (4) Other—Directedness domain (subjugation and self-sacrifice); and (5) Over-vigilance and Inhibition domain (Emotional inhibition and Unrelenting standards). Each item is answered on a 6-point Likert scale. Higher scores demonstrate greater level of distorted view about the self and others. Previous studies have shown that YSQ-SF is a measure with strong psychometric properties [36]. YSQ-SF has also been found to be a reliable and valid instrument for assessing EMSs among Iranian populations [37].

The DERS [27] is a 36-item questionnaire that measures emotion dysregulation through six domains consisting of difficulties in accepting emotional response (non-acceptance), difficulties in engaging purposeful behavior (goal), difficulties in controlling impulses (impulse), lack of emotional awareness (awareness), limited access to emotion regulation strategies (strategies) and lack of emotional clarity (clarity). Each item is scored on a 5-point Likert scale and higher scores show greater difficulty in emotion regulation. Based on the findings of previous studies, the DERS is a reliable and valid measure with internal consistency between 0.76 and 0.93 [38, 39] and test–retest reliability of 0.53–0.82 [40]. The Persian version of DERS has shown strong psychometric properties among Iranian individuals [41, 42].

The Bing Eating Scale (BES) [41] was designed to assess behavioral manifestations, emotions and cognitions related to binge eating in obese patients. The BES is a 16-item, self-administered scale. Each item includes 3 or 4 statements that are weighted between 0 and 3. Previous studies have indicated appropriate psychometric properties of BES. The sensitivity and specificity of BES were found to be 0.98 and 0.48, respectively [43]. Psychometric properties of BES was examined by Dezhkam, Moloodi, Mootabi and Omidvarin in Iran and they reported this scale is valid and reliable for assessing BE [44].

Results

Demographic and descriptive summary

The Kolmogorov–Smirnov test was used to examine whether data met assumptions of parametric tests. For variables with normally distributed scores, t tests were used to compare the two groups. Otherwise Mann–Whitney U tests were used.

No significant difference was found between the two groups in age and years of education. Expectedly, mean BMI of participants with obesity was higher than normal weight participants significantly. Details of these results are shown in Table 1.

Table 1 Results of t test for participants’ characteristics
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The independent t test and Mann–Whitney U were conducted to determine differences between the obese and normal weight groups in term of EMSs (see Tables 2 and 3). T test and Mann–Whitney U analyses revealed that the obese group scored significantly higher than the normal weight group on the following EMS subscales: emotional deprivation, mistrust, failure, dependency, enmeshment, self-sacrifice, especially abandonment, social isolation, vulnerability, self-control and subjugation. However, women with obesity did not differ from normal weight women concerning shame, entitlement, emotional inhibition and unrelenting standards.

Table 2 Results of Mann–Whitney test between the two groups on EMS subscales
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Table 3 Means and standard deviations on EMSs scores and differences between the two groups
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Since the distributions of DERS subscales were normal, independent t test were performed to examine the differences between two groups in relation to DERS subscales. Table 4 shows the means of both groups and the result of t tests. The obese group had higher scores on the goal, impulse and strategies subscales than the normal weight group. However, they did not differ significantly from their normal weight counterparts on the non-acceptance, awareness and clarity subscales.

Table 4 Results of t test between the two groups on DERS subscales
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Table 5 shows that compared to normal weight women, the obese women obtained significantly higher on BES.

Table 5 Result of t test between the two groups on BE score
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Discussion

The purpose of the present study was to examine the cognitive, emotional and behavioral differences between obese and normal weight women. Overall, the results indicated that the severity of EMSs, DER and BE is higher in obese women than the normal weight individuals. In particular, obese women seemed to believe that one’s need for nurturance and emotional support is not met by others (emotional deprivation schema), that others maltreat and deceive them (mistrust schema), that they are not as adequate and talented as their peers (failure schema) and that they need others for managing their daily life (dependency schema). In addition, they presume that individuality is determined by over-connection and over-involvement with others, especially parents (enmeshment schema), one must satisfy others voluntarily in expense of one’s satisfaction (self-sacrifice), individual is obliged to obey others to prevent anger and abandonment at the expense of one’s own needs (subjugation), others may cease their nurturance and protection suddenly (abandonment schema), one is isolated and different from other people (social isolation schema), unpredictable and uncontrollable catastrophes may strike at any time (vulnerability schema) and one cannot tolerate frustration and discomfort (self-control schema). These results are consistent with the findings of previous studies showing greater severity of negative beliefs towards self and others in individuals suffering from obesity [24, 25, 45]. Based on Young’s theory, early maltreatment could lead to the development of negative assumptions about self and others in obese individuals. Previous studies have found that obese individuals report more instances of childhood maltreatments (physical, sexual, emotional abuse and physical and emotional neglect) than the normal weight individuals [46, 47]. Longitudinal research is required to determine why obese people hold negative assumptions about themselves and others. Stigmatization, teasing and self-criticism are other factors that could impact the self-schemas of obese women [48].

It was found that compared to normal weight individuals, obese women had more difficulties in controlling their impulses, engaging in goal-directed behaviors and accessing functional strategies while experiencing negative emotions. This pattern is congruent with the growing literature indicating a higher prevalence of emotional and binge eating among obese patients [28, 49]. Consistent with Linehan’s conceptualization, [50] emotion dysregulation derives from emotional vulnerability. Emotional vulnerability consists of hypersensitivity to emotion-related stimuli (reacting rapidly to an emotional stimulus), emotional intensity (intense emotional reaction) and slow return to emotional baseline. These factors could increase the use of emotional and binge eating as coping methods among obese women.

Indeed, results of the present study revealed a higher severity of binge eating behavior in the obese group compared to normal weight group as well. The affect regulation model of binge eating considers eating as a strategy for reducing negative emotions [51]. Whiteside et al. [52] found that difficulties in accessing emotion regulation strategies and the lack of emotional clarity predicted binge eating. Claes et al. [53] investigated the functions of different kinds of non-suicidal self-injury (NSSI) among women with eating problems and found that the most important function of NSSI is affect regulation; in particular following NSSI, positive low arousal affects are increased and negative high arousal affects are decreased. Claes et al. concluded that using NSSI as an affect regulation strategy could have an addictive mechanism like releasing opioid that can lead to pain reduction or involvement of dopamine that gives rise to positive reinforcement of NSSI as an affect regulation strategy. Given these findings, binge eating might have a mechanism like NSSI in obesity. In other words, it might lead to reduction in emotional pain via releasing opioid or involvement of dopamine. However, this assumption needs further exploration.

Clinical implication

On one hand, literature review indicates more psychopathology, emotional eating and binge eating in obese women seeking treatment compared to obese individuals who do not seek treatment and the normal weight women [57]. Additionally, obese women with morbid obesity are more depressed and are more likely to suffer from history of psychiatric complications and unrealistic expectations related to weight loss [58]. On the other hand, binge eating is a predictor of weight regain and long-term outcome of bariatric surgery even though short-term outcome is acceptable [59].

The findings of the current study regarding the higher cognitive, emotional and behavioral psychopathology among obese women candidate for bariatric surgery suggest possible strategies for intervention that can reduce the risk of weight regain and poor outcomes in long term. Cognitive behavioral conceptualization and interventions for obesity could address the psychological mechanisms that appear to maintain obesity. Cognitive theory [45] postulates that the activation of negative self-schemata gives rise to DER and dysfunctional coping such as negative emotional coping and binge eating. Weight loss and weight maintenance depend on concrete behaviors such as dietary regimen and physical activities and not just emotionally driven coping behavior. However, the evidence suggests that cognitive, emotional and behavioral psychopathology inhibits adherence to dietary regiments and physical activity schedules. In other words, the activation of negative beliefs about self, others and one’s appearance may lead to negative emotions, and the result in emotion dysregulation creates a vulnerability to eating as a coping strategy for the negative emotions. Binge eating, in turn, is a behavior contrary to the goal of weight loss, and could activate one’s negative beliefs about self and appearance. This process creates a vicious cycle in obese individuals. Targeting these emotional, cognitive and behavioral mechanisms, especially, in bariatric surgery seekers, could prolong postsurgical weight loss and improve their quality of life.

We note several study limitations. The generalizability of findings of the study is restricted to obese women candidate for bariatric surgery. It is recommended that the future studies also examine the EMSs, DER and BE among obese men and compare them with obese women. Utilizing self-report questionnaires for gathering data is another limitation of present study because of their vulnerabilities to bias. The present study investigated obese women as a homogeneous group while previous studies indicated psychopathological differences between obese individuals with or without BED [54–56]. Finally, investigating differences between obese patients with or without BED who seek bariatric surgery with regard to EMSs, DER and BE should be considered in future studies to enhance our knowledge about psychopathology and treatment of obesity.