The impact of trait and state anger on emotional eating following laboratory based mood induction

A laboratory based mood induction study was conducted on 61 non-clinical participants at the University of Massachusetts Medical School with secondary analysis of data to assess the impact of trait and state anger on emotional eating behavior based on post-mood induction caloric consumption. Results of linear regression, ANOVA and general linear model (GLM) analyses revealed a significant correlation of trait anger (as assessed by STAS score at participant screening) with post-induction caloric intake (p = .0008), after removal of data point outliers. State anger, as assessed by difference in preand postinduction POMS score, was not significantly correlated with caloric intake (p = .12). There was no evidence of a significant interaction effect between trait and state anger (p = .13). Gender was associated with increased caloric intake in male participants (p < .0001); however, this was apparent following both anger and neutral mood inductions. The induction procedure (anger versus neutral mood induction) and order of inductions were controlled for and were not significantly related to caloric intake. The findings allowed for development of an overall regression equation based on trait anger, state anger, and gender which achieved an R 2 of . 32 (p < .0001), and suggested that for each one point increase in trait anger (by STAS score) there was a corresponding increase of 15 calories consumed. The importance of trait anger as a contributing factor in emotional eating deserves further study in larger samples and more natural settings, in particular to evaluate its potential contribution to pathologic eating behaviors and resultant disordered eating and obesity. Anger and Emotional Eating 8 CHAPTER ONE: INTRODUCTION Emotional eating describes a phenomenon whereby eating occurs in response to stress or to negative moods such as anger, depression and anxiety (Arnow, Kenardy, & Argas, 1998; Greeno & Wing, 2004; Solomon, 2001). There is evidence that both personality traits and transitory emotional states may predispose individuals to emotional eating (Macht, Roth & Ellgring, 2002). Eating in response to emotion may ultimately lead to obesity, eating disorders and other serious morbidity (Hays & Roberts, 2008). Obesity has become an epidemic in the United States, with over two thirds of Americans considered overweight, and one third considered obese (Centers for Disease Control, 2010). Anger is an emotion that may be an important factor predisposing individuals to emotional eating (Narita et al., 2007). The propensity to become angry is an underlying personality trait, characterized by a tendency to experience frequent and intense episodes of this emotion (Spielberger, 1988). The interaction of both this underlying propensity and transitory anger states may play an important complementary role in triggering emotional eating. If underlying personality traits, emotional states, and demographic factors that predispose individuals to emotional eating can be identified, then early clinical surveillance, intervention and prevention may be possible. The present study will evaluate the influence of baseline trait anger, and induced state anger, on emotional eating following laboratory-based mood induction. It is anticipated that these findings may help identify psychological Anger and Emotional Eating 9 characteristics and situations that make individuals more vulnerable to emotional eating. The background literature on the etiology and public health significance of emotional eating and associated psychological and physical conditions will be discussed to provide a rationale for the current investigation. The focus will be on the relationships among trait anger (the propensity to experience anger episodes), state anger (transitory emotional states of anger) and emotional eating following induction of an anger state. The discussion will also include a review of the methodological limitations and unanswered questions in the extant literature. Rationale and Significance of the Problem A link between emotion and eating behaviors, such as overeating or binge eating, has been documented (Chua, Touyz, & Hill, 2004; Engelberg, Steiger, Gauvin, & Wonderlich, 2007; Greeno & Wing, 1994; Masheb & Grilo, 2006; Nguyen-Michel, Unger, & Spruijt-Metz, 2007; Penas-lledo, de Dios, & Waller, 2004; Pinaquy, Chabrol, Simon, Louvet, & Barbe, 2003; Wallis & Hetherington, 2009). Researchers who have examined the idea that emotion can lead to overeating behaviors and potentially to being overweight or to obesity have found a stronger link between negative than positive emotions and eating (Edman, Yates, Aruguete, & De Bord, 2005; Goossens, Braet, & Decaluwe, 2007; Nguyen-Rodriguez, Chou, Unger, & Spruijt-Metz, 2009; Strien, Engels, Leeuwe, & Snoek, 2005). Hypotheses regarding the role of negative affect as a moderator of emotional eating range from temporally-related functions of eating to reduce or lessen states of emotional distress Anger and Emotional Eating 10 to hypotheses which suggest that emotional eating may function to block intolerable emotional experiences. Chronic patterns of emotional eating may eventually trigger binge eating behaviors as well as disinhibited patterns of food consumption, as observed in some types of eating disorders (Masheb & Grilo, 2006). The phenomenon of emotional eating and its role as a potential precursor to more serious eating disorders or obesity has also been described (Streigel-Moore & Franko, 2003). Research in the area of negative affect and emotional eating has mainly considered negative affect as a single homogeneous construct. However, negative affect is more comprehensively conceptualized as a variety of distinct mood states that includes anger, depression, and anxiety. Although there is literature supporting the notion of a link between the general concept of negative affect and emotional eating (Arnow, Kenardy, & Agras, 1995; Burton, Stice, Bearman, & Rohde, 2007; Costanzo, Reichman, Friedman, & Musante, 2001; Greeno & Wing, 1994; Solomon, 2001; Waters, Hill, & Waller, 2001), few observers have focused on specific negative affects, such as anger, depression or anxiety, and the particular functions these distinct emotions may play in putting individuals at risk for emotional eating. It is plausible that not all negative affective states result in similar eating behaviors. Studying specific mood states and the resulting impact on eating may lead to a more specific understanding of eating behavior, and ultimately facilitate development of more targeted and precise clinical interventions. Research that has been conducted on specific negative affects and eating behavior has found that there are different responses to varied negative mood states Anger and Emotional Eating 11 (Macht, 1999). For example, there is evidence suggesting that when individuals experience a state of physiological arousal and activation, such as during states of anger and resultant heightened hostility, food consumption may increase (Miotto et al., 2008). Conversely, other investigators have described that during periods of sadness individuals tend to eat less as a result of appetite suppression due to physiological slowing (Devlin, Goldfein, & Dobrow, 2003; Sysko & Hildebrandt, 2009; Wilfley, Bishop, Wilson, & Agras, 2007). In these two cases, differing negative affects have a significant, albeit opposite, effect on eating behavior. Hence, the general category of negative affect is made up of heterogeneous emotions, which need to be separately studied to better understand their specific impact on eating behavior. Prior studies which focused on the general topic of negative affect may have lacked the precision to describe and consider the potentially confounding impact of combining all negative emotions in the single category of negative affect. The topic is further complicated by considering the differences between state and trait emotions. State emotions are transient, defined episodes of emotion, while traits are more consistent and enduring underlying personality characteristics and tendencies. Distinguishing these situational responses from more fundamental characteristic tendencies is another important consideration in assessing the role of affect on eating behavior. Research into emotional eating should consider both intrinsic personality traits as well as transient states that contribute to manifested behaviors. Few prior studies have considered this level of detail in their assessment. Anger and Emotional Eating 12 To gain a fuller understanding of both trait and state emotions, careful empirical research is required. Limitations of Literature in this Area Evaluations of emotional eating have suggested that negative affect is correlated with this behavior (Geliebter & Aversa, 2003). However, less attention has been focused on the specific negative affect of anger and its role in emotional eating. There are a few studies that focus specifically on anger, such as its association with health conditions like cardiovascular disease and hypertension (Zaitsoff, Geller, & Srikameswaran, 2002); however, the relationship of these conditions to emotional eating behavior has not been clearly elucidated. State anger regulation or expression among chronic low back pain patients has been studied by anger induction, as well as the potential moderating effects of level of trait anger (Burns, 2008). However, despite these studies, in general the literature on negative affect fails to focus on anger, or its trait and state features, as a distinct type of negative affect. In general, the literature that does consider anger suffers from another limitation. Many studies of anger have focused on measurement of hostility, which is the behavioral or physiological response to the emotion of anger (Deffenbacher, et al., 1996). It is unclear whether the descriptions of hostility in prior studies have a strong correlation with trait anger, which is be