Trait anxiety, but not trait anger, predisposes obese individuals to emotional eating

Abstract

The present study examined whether trait anxiety and trait anger are associated with vulnerability to emotional eating, particularly among obese individuals. Lean (n = 37) and obese (n = 24) participants engaged in a laboratory study where they completed measures of trait anxiety and trait anger at screening and then completed 3 counterbalanced experimental sessions involving different mood inductions (neutral, anxiety, anger). Following each mood induction, participants were provided with snack foods in a sham taste test. Models predicting snack intake revealed a significant trait anxiety × body mass index group interaction, such that high trait anxiety was positively associated with food intake for obese individuals, but not their lean counterparts. Contrary to the hypothesis, trait anger was not associated with food intake for obese or lean participants. Results suggest that trait anxiety may be a risk factor for emotional eating among obese individuals.

Introduction

The influence of negative emotions on food intake is complex and not completely understood (Macht, 2008). Research shows that negative emotions can decrease food intake in some individuals and circumstances (e.g., Baucom and Aiken, 1981, Heatherton et al., 1991) and increase food intake in others (e.g., Lowe and Maycock, 1988, Willner et al., 1998). The latter is referred to as emotional eating, and to the extent that it leads people to consume more than their daily needs, weight gain and obesity can develop (Hays & Roberts, 2008). Obesity intervention studies also show that emotional eating is associated with poorer weight loss outcomes (Elfhag & Rossner, 2005).

Emotional eating has been observed in both obese and lean individuals (Greeno & Wing, 1994) and a critical review of the literature concluded that there is no relationship between body mass index and emotional eating (Allison & Heska, 1993). Thus, vulnerability to emotional eating does not appear to be simply a function of weight. Vulnerability to emotional eating is likely influenced by multiple factors. Individual differences in affective traits may account for some of the observed variability in the effects of emotions on eating. Jansen et al. (2008) reported that obese individuals high in negative affect consumed more food than individuals low in negative affect following a negative mood induction, relative to a neutral mood induction. In contrast, lean individuals consumed comparable amounts of calories in the negative and neutral mood induction conditions, regardless of their level of negative affect (Jansen et al., 2008). A limitation of this study is the use of state measures of negative affect, which capture transient moods, but not necessarily affective traits. Further research is needed to explore whether trait negative affect could possibly be a risk factor for emotional eating in obese individuals.

Also unknown is whether specific types of trait negative affect differentially impact emotional eating. Initial research suggests that trait anxiety and trait anger may be particularly important predictors of emotional eating. Initial evidence suggests that trait anxiety is associated with higher food consumption under stress (Pollard, Steptoe, Canaan, Davies, & Wardle, 1995). Other support for a role of trait anxiety is provided by studies showing a high prevalence of anxiety disorders (37%) among people with binge eating disorder (Grilo, White, & Masheb, 2009). Similarly, elevated trait anger has been observed in cross-sectional studies of individuals with bulimia (Fassino, Daga, Piero, Leombruni, & Rovera, 2001) and binge eating disorder (Fassino, Leombruni, Piero, Abbate-Daga, & Rovera, 2003) compared to lean and obese individuals without a diagnosed eating disorder. Although emotional eating is a hallmark of bulimia (Ouwens et al., 2009, Stice et al., 1998) and binge eating disorder (Stein et al., 2007, Wolfe et al., 2009), most individuals who endorse emotional eating do not meet criteria for bulimia or binge eating disorder (Fischer et al., 2007, Lindeman and Stark, 2001). Thus, the extent to which trait anger and anxiety increase vulnerability to emotional eating in non-eating disordered populations is not well-explored.

The present study examined whether trait anxiety and trait anger are associated with vulnerability to emotional eating, particularly among obese individuals. Lean and obese participants completed measures of trait anxiety and trait anger prior to undergoing neutral, anxiety, and anger mood inductions on separate days. Following each mood induction, participants were given highly palatable foods in a sham taste test. After the sham taste test, food intake was objectively measured. Two different hypotheses were tested: (1) Whether higher trait anxiety is associated with greater food intake following an anxiety mood induction for obese, but not lean individuals and (2) whether higher trait anger is associated with a greater food intake following an anger mood induction for obese, but not lean individuals.