نقش تعدیل کننده فوریت منفی بر ارتباط بین عاطفه, خویشتن داری غذایی و مصرف کالری: مطالعه تجربی

The present study tested the moderating role of negative urgency (NU), a personality trait characterized by a tendency to act impulsively in the face of emotional distress, on the associations between dietary restraint, affect, and calorie intake following a mood manipulation. Undergraduate women reported levels of NU and dietary restraint and underwent a failure task intended to induce a negative mood. Participants then completed mood ratings and a sham taste assessment task in which calorie intake was measured. NU enhanced the association between dietary restraint and calorie intake, such that participants who reported higher levels of dietary restraint consumed more calories, and this effect was strongest among participants who were high on NU. NU also enhanced the association between positive, but not negative, affect and calorie intake. Specifically, participants who were high on NU and reported lower positive affect consumed more calories than participants who were low on NU. These findings suggest that NU plays a synergistic role in increasing calorie intake among individuals who engage in dietary restraint or experience low positive affect.

Impulsivity, broadly defined as a tendency to think, control, and plan insufficiently, often results in maladaptive behavioral responses, including disordered eating behavior (Rosval et al., 2006). Indeed, considerable research has related impulsivity to binge eating (Hartmann et al., 2010 and van Strien et al., 2005); however, the operationalization of impulsivity has been inconsistent throughout the eating pathology literature (see Waxman, 2009 for review). In an attempt to clarify the various conceptions of impulsivity in the broader personality literature, Whiteside and Lynam (2001) provided evidence that omnibus measures of “impulsivity” are better characterized by a multi-factor model of moderately associated factors that all lead to rash action. Of these, negative urgency (NU), the tendency to act impulsively in the face of emotional distress, has been shown to have moderate to large associations with binge eating (Fischer, Smith, & Cyders, 2008). Individuals high on NU may be vulnerable to binge eat because they are more likely to partake in negatively reinforcing and avoidant coping behaviors under conditions of emotional distress (Fischer, Anderson, & Smith, 2004). However, the relation between NU and eating behaviors in the context of emotional distress has not been demonstrated experimentally. In addition to NU, dietary restraint and emotional distress have been implicated as risk factors for binge eating (Stice, 2001). Dietary restraint refers to the conscious effort to restrict calorie intake with the intent to lose or maintain weight and has been suggested to diminish cognitive resources necessary to retain self-control, subsequently increasing risk to binge eat (Muraven & Baumeister, 2000). Indeed laboratory demonstrations of binge eating behavior have documented increased calorie intake following cognitive tasks (Kahan, Polivy, & Herman, 2003) and negative mood inductions (Heatherton et al., 1998 and Tanofsky-Kraff et al., 2000) among restrained eaters. However, controlled weight loss trials have prospectively documented decreased binge eating among individuals randomly assigned to low-calorie diets (Presnell and Stice, 2003 and Reeves et al., 2001), suggesting that dietary restraint may actually be protective against eating pathology over time. These mixed findings complicate the understanding of how dietary restraint causally impacts binge eating behavior. Furthermore, emotional distress, characterized by high levels of negative affect (e.g., anger, shame, and guilt) and low levels of positive affect (e.g., sadness, lethargy, and depression) is associated with both increased and decreased calorie intake (Greeno & Wing, 1994). A loss of appetite and decreased calorie intake are considered normal responses to stressful emotional stimuli (Kinzig, Hargrave, & Honors, 2008). However, some individuals respond paradoxically to emotional distress by increasing calorie intake, placing them at risk to binge eat (Bekker, van de Meerendonk, & Mollerus, 2004). It has been suggested that these individuals eat in an effort to cope with emotional distress as the positively reinforcing nature of palatable foods (Volkow & O’Brien, 2007) may provide both comfort and distraction from emotional distress (Bekker et al., 2004). In line with this evidence, research has documented both increased (Chua et al., 2004 and Udo et al., 2013) and decreased (Schachter, Goldman, & Gordon, 1968) calorie intake in response to high negative and low positive affect. Inconsistencies in prior research investigating the effects of dietary restraint and emotional distress on binge eating behavior may be partially attributable to unique individual differences that influence eating behavior. NU may serve as a determinant of risk for binge eating behavior following emotionally distressing events, leading individuals high on NU, who engage in dietary restraint or experience emotional distress, to increase, rather than decrease calorie intake. Emerging evidence indicates that NU prospectively enhances risk for binge eating among restrained eaters (Emery, King, Fischer, & Davis, 2013), suggesting that individuals who characteristically have lower average levels of self-control may be particularly vulnerable to the self-control depleting effects of dietary restraint. Furthermore, because impulsive individuals tend to direct attention towards reward stimuli (Hou et al., 2011), the reinforcing nature of palatable foods (Volkow & O’Brien, 2007) coupled with their accessibility (Brownell & Horgen, 2004) may make food intake an attractive choice for mood regulation. Thus, individuals high on NU may be particularly likely to engage in an easily accessible and effective, albeit maladaptive, behavior, such as increased calorie intake, when confronted with emotional distress. Accordingly, the present study aimed to investigate how NU, dietary restraint, and affect interact to alter calorie intake among individuals experiencing emotional distress. The first aim of the study was to test the moderating effect of NU on the association between dietary restraint and calorie intake following experimentally manipulated affect. The second aim of the study was to determine whether NU enhanced the association between experimentally manipulated affect and subsequent calorie intake. We hypothesized that NU would enhance the effects of dietary restraint, high negative affect, and low positive affect on calorie intake.

The aim of the present study was to test whether NU moderated the effects of dietary restraint as well as positive and negative affect on calorie intake following experimentally induced negative mood. We found that dietary restraint was associated with decreased calorie intake among those with lower levels of NU but increased calorie intake among those with high NU. Some research suggests that the risk of engaging in dysregulated eating behaviors increases at elevated levels of dietary restraint (Muraven & Baumeister, 2000). Given that NU is a disposition related to poor inhibitory control in the face of emotional distress (Whiteside & Lynam, 2001), dietary restraint may function as a mechanism that further reduces the capacity of individuals high on NU to exert control over their eating behavior while individuals low on NU are able to retain cognitive control over their eating behavior. Contrary to expectations, NU did not moderate the effect of negative affect on calorie intake. It may be that the experimental paradigm utilized in this study did not elicit a sufficiently strong emotional distress response. Although participants in the experimental condition had higher overall negative affect than participants in the control condition, their average negative affect remained relatively low. Thus, the negative affect experienced by participants may not have been intense enough to prompt individuals to drastically increase calorie intake. Alternatively, past research has demonstrated that negative affect is not consistently associated with increased calorie intake (Greeno & Wing, 1994), and decreased calorie intake is actually considered a normative response to emotional distress (Gold & Chrousos, 2002). As such, it may be that participants tended to respond to the negative affect associated with the mood manipulation by not increasing calorie intake.