Abstract
<p>Hunger is an essential human process and develops through both physiological and neurological mechanisms. Hunger is driven by secretion of molecules and hypothalamic neural circuits that stimulate appetite and promote food intake. Pathways to hunger may also be influenced by higher-order cognitive and emotional processes to ultimately impact food intake and eating behavior. For example, increased symptoms of depression, anxiety, anger, and hostility (hereby referred to as “hostile negative affect”) are suggested to increase hunger and food intake. Additionally, perceived stress has been shown to both decrease and increase hunger and food intake. The stress-induced eating hypothesis posits that, when faced with psychological stress, food consumption is increased. It has been hypothesized that the vulnerability to stress-induced eating is mediated by cognitive processes termed “eating styles”, which may be distinct or overlapping within individuals. The literature describes four eating styles: restrained eating, emotional eating, external eating, and uncontrolled eating. Restrained eating is the voluntary restriction of food intake, often to control body shape or lose weight. Emotional eating involves increasing food intake in response to a negative emotional state to alleviate emotional distress. External eating refers to the extent to which one’s food consumption is sensitive to the characteristics and features of food, such as appearance, smell, and taste. Uncontrolled eating refers to the disinhibition of food intake in the absence of hunger. Each of these four eating styles has been individually associated with increased hostile negative affect. Restrained, emotional, external, and uncontrolled eating are known to affect hunger and food intake. Previously, hostile negative affect has been linked to increased food intake, but mediators of this relationship have not been explored. In addition, although the stress-induced eating hypothesis posits that perceived stress leads to food consumption, it is unclear what mediates this association. Based on existing literature linking perceived stress to eating style and eating style to food intake, the present study has proposed the stress – hunger relationship is mediated by restrained, emotional, external, and uncontrolled eating. Thus, the primary aims of this study were to examine: 1) perceived stress as a mediator between hostile negative affect and hunger; and 2) eating styles as mediators of the relationship between hostile negative affect, perceived stress, and hunger. The study used data from a sample of 143 healthy adults (65% men) with no psychiatric or other diagnosed cardiometabolic conditions. Hostile negative affect, perceived stress, and eating style were measured using the Cook and Medley Hostility scale, Profile of Mood States, Perceived Stress Scale, Dutch Eating Behavior Questionnaire, Three-Factor Eating Questionnaire-Revised 18- item version, and Restraint Scale. Hunger was measured every 3.5 hours on a visual analog scale over the course of a 2-day inpatient stay, wherein ratings were obtained 5 times per day prior to meals. Meal content was manipulated such that fat and protein content per meal was constant but carbohydrate content was “standard” on one day and “doubled” on another day. Total caloric intake was adjusted by sex, body surface area and minimal energy requirements. Study aims were analyzed using structural equation modeling (SEM). As expected, hunger was significantly diminished on the double carbohydrate load day due to increased overall caloric intake. SEM yielded latent constructs of Hostile Negative Affect (second-order factor from Hostility and Negative Affect), Restrained Eating, Emotional Eating, and Hunger. Analyses suggested the combination of emotional, external, and uncontrolled eating styles into a single latent factor, which we termed “Uncontrolled Eating”. The final model had good fit when controlling for covariates, χ2(139) = 162.92, <em>p </em>= .08, CFI = .98, RMSEA = .04. Hostile Negative Affect had a significant positive effect on Perceived Stress (β = .53, <em>p </em>< .001). Perceived Stress had significant positive effects on Restrained Eating (β = .27, <em>p </em>= .01) and Uncontrolled Eating (β = .18, <em>p </em>= .03). Restrained Eating also had a significant positive effect on Uncontrolled Eating (β = .46, <em>p </em>< .001). Of note, Restrained Eating had a significant negative effect on Hunger (β = -.38, <em>p </em>= .01), whereas Uncontrolled Eating had a significant positive effect on Hunger (β = .28, <em>p </em>= .02). Initially, Perceived Stress did not mediate the Hostile Negative Affect-Hunger relationship. However, the path from Hostile Negative Affect to Hunger reached significance once eating styles were added to the model (β = .25, <em>p </em>= .04). Overall, 3 pathways from Hostile Negative Affect to Hunger were identified: a direct path from Hostile Negative Affect to Hunger, an indirect path through Perceived Stress and Restrained Eating, and an indirect path through Perceived Stress and Uncontrolled Eating. Tests of indirect effects revealed the Hostile Negative Affect-Hunger relationship was partially explained by indirect effects of Perceived Stress and Restrained/Uncontrolled eating styles, in addition to a direct effect of Hostile Negative Affect on Hunger. The full model explained 17.2% of the variance in Hunger. The present findings identified Restrained Eating and Uncontrolled Eating styles as potential mediators of the distress-Hunger relationship. The model structure suggests a mechanism for distinguishing whether perceived stress may facilitate or suppress hunger and food intake. To our knowledge, this is the first study demonstrating associations between Hostile Negative Affect and self-reported hunger, independent of control variables, indicating that elevations in hostility and negative affective traits may facilitate hunger regardless of sex, age or the extent of central body fat deposition.</p>